Mosaic from Raw Scenes module


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Description


The Mosaic from Raw Scenes module reads the input-scenes folder for satellite imagery and creates a series of child jobs to produce a final mosaic image.
Note: The Mosaic from Raw Scenes module does not support tri-stereo data.
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Parameters


Name Caption
Input Scenes Input file, folder, or text file
Output Folder Output folder
Ingest Method Link or import data
Output File Type Output file type
Output File Options Output file options
Overwrite Results Overwrite existing results
Send Email Email notification settings
Product Type Type of product to mosaic
Math Model Filter Input math model filter
RF Math Model Order RPC adjustment order
Source Background Type Source background type
Source Background Value Source background pixel value
Output Background Value Output background value
DEM Source DEM tile source
Master Matching Channel Master matching channel
Reference Images Input reference images folder
Reference Channel for Matching Reference image channel to use for matching
Sampling Method GCP sampling method
GCP Samples Number of GCP samples to collect
Matching Algorithm Matching algorithm
Collection Strategy Number of passes for GCP collection
Search Radius Search radius (pixels)
Minimum Score Minimum score (percentage)
Chip Database File Input chip database file
Chip Channels Input chip database channels
Chip Matching Algorithm Chip Matching algorithm
Chip Search Radius Chip Search radius (pixels)
Chip Minimum Score Chip minimum score (percentage)
Road Network Input road network path
Road Width Field Name Input road width field name
Road Width Scale & Offset Input road width scale & offset
Polygon Vector File Input polygon vector file
GCP Text Files Input GCP text file or files
GCP Text File Format File format of GCP text file
Water Mask File Input water-mask file
Refine GCPs Whether to refine GCPs
Rejection Method GCP rejection method
Rejection Method Thresholds GCP rejection method thresholds
Maximum GCPs Maximum GCPs to accept
Minimum GCPs Minimum GCPs to accept
Collect Tie Points Collect tie points
Sampling Method Tie-point-sampling method
TP Samples Number of tie point samples to collect
Trials per TP Number of attempts to collect a TP for each candidate
Distribution Area Area of image in which to distrbute TPs
Matching Algorithm Matching algorithm
Matching Channels Matching channels
TP Search Radius Tie point search radius
TP Minimum Score Tie point minimum score
TP Rejection Method Tie point rejection method
TP Rejection Method Thresholds Tie point rejection method thresholds
Pansharpen Order Pansharpening order
Pansharpening Method Pansharpening method to use
Multispectral Sharpening Channels Multispectral sharpening channels
Multispectral Reference Channels Multispectral reference channels
Resampling Method Resampling method
Enhance Whether to enhance UNB pansharpened images
Edge Sharpen Amount of sharpening to image edges
AdaptRadiometry Adapt radiometric values to input MS images
Output Map Units Output projection
Panchromatic Pixel Output Size Panchromatic output pixel size
Multispectral Pixel Output Size Multispectral output pixel size
Resampling Method Resampling method
Resampling Method Extra Options Extra options for resampling method
Sorting Method Image sorting method
Starting Image Starting image
Normalization Method Normalization method
Normalization Method Extra Options Normalization options
Color Balancing Method Color-balancing method
Color Balancing Extra Options Color-balancing options
Global Color Balance Mask File Global color-balancing mask file
Global Color Balance Mask Layer Global color-balancing mask layer
Global Color Balance Mask Segment Global color-balancing mask segment
Cutline Method Cutline method
Cutline Method Extra Options Cutline options
Auto Constrain Constrain cutlines to image centers
Factor Auto Constrain Factor value
Simplify Cutlines Simplify generated cutlines
Simplification Level Level of simplification
Global Cutline Avoidance Mask File Global cutline-avoidance mask file
Global Cutline Avoidance Mask Layer Global cutline-avoidance mask
Global Cutline Avoidance Mask Segment Global cutline-avoidance mask segment
Area of Interest File Area-of-interest vector file
Crop Tiles to AOI Crop tiles to area of interest
Tile Base Name Base name
Tile Specification Mosaic tile specification
Height Height of the mosaic tile, in pixels
Width Width of the mosaic tile, in pixels
Vertical Overlap Vertical overlap between tiles
Horizontal Overlap Horizontal overlap between tiles
Tile File File containing tile-definition layer
Segment Number Vector segment in tile file
Field Name File containing tile-definition layer
Coordinate Type Type of coordinates in script
Tile Position Transformation Defines grid to align mosaic tiles
Blend Width Cutline blend width
Create Source Map Create source map
Existing Tile Rule Rule for processing existing tile
Delete Empty Tiles Whether to delete empty tiles
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Parameter descriptions

Input Scenes

The path and name of the folder containing the raw images to process.

This parameter can be specified by using any of the following:

Output Folder

The path and name of the folder to which to write the output files.

If tiled output is specified, tiles are processed by the processing nodes configured by the CATALYST Enterprise, and are stored in the specified output folder. Local copies of the tiles on processing nodes are automatically deleted. The output tile file names are generated automatically according to the Tile Base Name.

Ingest Method

Select whether to link or import the data specified in the scene folder.

You can select from the following:

Output File Type

The format of the output file.

For more information on the supported file formats, see GDB-supported file formats.

Output File Options

The options to apply when creating the output file or files. The available options are specific to the file format; in each case, the default of no options is allowed.

For more information on the options available for the output file type you specify, see GDB-supported file formats.

Overwrite Results

Select this check box to overwrite the existing output files, if any exist. If this check box is left clear, and an output file exists in the relevant folder, the status of the job displays a message informing you of the existence and name of the output file. The message is also written to the event log of the job.

Send Email

If necessary, you can set up CATALYST Enterprise to send an email notification on job start and job completion.

With this check box selected, an email message is sent to each address specified in the Email Addresses box after the job starts and on completion.

You can specify one or more addresses, and each must be separated by a comma or a semi-colon. The email address of the user currently logged in displays by default.

Product Type

From the list, select the type of product you want to mosaic.

Available options are:

This parameter is optional.

Math Model Filter

The math model to use for collection of ground control points (GCPs) and, subsequently, orthorectification.

Available options are:

The module first attempts to use the selected math model. If required information is missing from the user-defined math model, the module automatically tries to use another math-model option, and displays a warning message.

RF Math Model Order

When using the Rational Function with satellite imagery, you can modify the RF math model to better agree with collected ground control points (GCPs) by selecting the correct RF math-model order.

Typically, performing a first-order transformation is best, except when the GCPs are not well distributed. If your GCPs are clustered together, a first-order transformation may introduce new and significant errors in the image away from the GCPs. If your GCPs are not well distributed, you will probably obtain better results with the zero-order transformation.

Source Background Type

The method to use to determine which pixels in the source image to process as background (NoData) pixels. In general, if a pixel is considered NoData, the module processes it in a specific manner.

If the Any option or the All option is selected, a value must be specified for the Source Background Value parameter.

Available options are:

For specific examples, see the Source Background Value parameter description.

Source Background Value

The source background value or values when the Source Background Type parameter is set to:

The source background value is provided as either a single number (applied to all channels) or as a pixel "stack" (a comma-delimited list of values). If a pixel stack is provided, but the number of values does not equal the number of channels, the list is truncated or the last value is repeated as necessary. The background values provided is truncated to the range allowed by the source image data type.

The following examples apply to a 3-channel, 8-bit unsigned image:

Output Background Value

The background (NoData) value to use for pixels that are not populated.

The specified background value is truncated to the range allowed by the source image data type.

When you specify one value, all channels are set to the same NoData value. If you want to specify different values for various channels, separate the values with commas. For example, to specify -32768 for channel 1 and zero for channel 2 (and any subsequent channels), enter "-32768, 0".

DEM Source

The name of a single digital elevation model (DEM) file or a folder containing one or more DEM tiles.

This parameter can be specified by using any of the following:

The index.txt file lists the DEM files contained in the specified folder and provides information describing each DEM tile. The information in the DEM index file supersedes other DEM parameters in the module; all other DEM-related parameters are ignored. For more information about the format of the index.txt file and specific requirements for the individual DEM tiles, see Format of the DEM index file.

When the value of DEM Source is the name of an existing folder, the module searches that folder for a file named index.txt, and a set of DEM raster tiles. The index.txt file contains a single vector channel that lists the DEM files contained in the specified folder and provides information describing each DEM tile.

If no value is specified for this parameter, the module uses the default global DEM installed with CATALYST Enterprise (gmted2010).

Note: With some modules, the DEM Source parameter is mandatory. That is, if in the interface an asterisk appears beside the parameter label, it is mandatory and you must enter a value; otherwise, the parameter is optional.

Master Matching Channel

The channel from the input image to use for matching when collecting ground control points (GCPs). If no value is specified for this parameter, channel 1 is used, by default.

Reference Images

The path of a single reference image or a folder containing multiple reference images to be used for automatic collection of ground control points (GCP). Alternatively, you can enter a comma-delimited list of raster-image file names.

To use multiple GDB-supported geocoded reference images for automatic GCP collection, you can specify a reference-image folder (GDB-compatible) and an associated (GDB-compatible) digital elevation model for automatic GCP collection. The specified folder can contain multiple reference images to use for collecting GCPs.

Note: This module uses all of the images in the input folder. Ensure that the specified folder contains only the images destined for use as reference for automatic GCP collection. For example, in some cases, the mosaic tile folder contains a mosaic preview file and scaled tiles; because these are not appropriate for automatic GCP collection, ensure that there are no such files in the folder specified for Reference Images.

The value of Reference Images is an image file that has been orthorectified previously for use with to automatic GCP collection. The GCPs collected from one or more of the reference images are stored in a GCP segment of the PCISDK image. The module also creates an OrthoEngine project that contains the same GCPs for quality- assurance (QA) tasks and manual editing.

When collecting GCPs using reference images, the module searches for ORTHO_X_ACCURACY and ORTHO_Y_ACCURACY metadata tags in the images. When such tags are present, the module uses those values to determine the accuracy of each GCP, thereby weighting the value of that point against others. The ORTHO_X_ACCURACY and ORTHO_Y_ACCURACY metadata tags are set in the Index PIX File Creator module. If no metadata tags are found in the reference image, the GCP accuracy is calculated to be half of the resolution of the reference image.

Reference Channel for Matching

The channel from reference image to use for matching when collecting ground control points (GCPs). Channel 1 is the default.

Sampling Method

The method to use to create ground control point (GCP) samples from the source imagery.

Available options are:
The Grid and Susan options determine how to find the initial candidate positions in one image (the source image) for collecting sample points. The function builds a patch around each candidate position, and searches within that area for corresponding features in the overlapping images.

When collecting GCPs, the Grid option is recommended because the Susan option finds candidates on building corners that may not be represented in the digital elevation model (DEM), leading to GCPs with higher residuals due to height errors.

GCP Samples

The maximum number of ground control points (GCPs) to collect per reference image. For example, when a raw scene overlaps four reference images and you specify the value of this parameter as 50, the maximum number of GCPs collected is four times that value for a total of 200 (50 x 4 = 200).

If you are using the Grid option, available values are:

If using the Susan option, available values are:

Matching Algorithm

The algorithm to use for automated point matching.

Available options are:

When the two images being matched have similar gray values and appearances, Normalized Cross-Correlation (NCC) generally produces acceptable results. When there is a rotation or image-size error in the initial math models, NCC may produce better matching results than FFTP. Typically, this method also generates faster results, because the template size that NCC uses is smaller than that used by FFTP.

For more consistently accurate results, FFTP is recommended. This method uses a larger template size than NCC and, because it works in the frequency domain, it looks at the patterns of details in the image rather than the gray values in a small neighborhood, which NCC uses. This makes FFTP more robust than NCC when there is a large difference in brightness between images or when a major land-use change has occurred between the images. FFTP also allows for a better match between images of the same area from different sensors or spectral bands.

Collection Strategy

Number of passes in which to collect ground control points (GCPs) from reference images.

The available options are as follows:

The distance in the x and y directions from a starting location on the reference image over which the search for the best match with a fixed point on the input image is conducted.

The search radius is an estimation of error with the raw image's positional information and the digital elevation model (DEM) accuracy. If you know that your image is accurate to within 80 meters, and your DEM is accurate to within 200 meters, set the search radius to 280 meters. A larger search radius requires more processing time, because more locations are evaluated to determine the best match for a ground control point (GCP).

If this parameter is not specified, the function uses a default search radius based on the resolution of input data.

Minimum Score

The threshold value that controls whether a candidate ground control point (GCP) is accepted as a GCP or rejected. This parameter specifies the minimum-match quality that is considered acceptable, with 1.0 indicating a perfect match.

When using the Fast Fourier Transform Phase matching algorithm, this value is converted internally to a minimum acceptable phase-shift peak value.

When using the Normalized Cross-Correlation matching algorithm, this value specifies the minimum match score value required to accept a local match between the input and reference images as a GCP. The default value is 0.75.

Chip Database File

The path and file name of the chip database to use for automatically collecting ground control points (GCPs).

The module collects the GCPs from the chip database, and then automatically saves them to a GCP segment of the PCIDSK image associated with the GCP.

To improve the spatial accuracy of the collected GCPs, the chip database should contain high-quality image chips from a comparable sensor taken in similar conditions and be well-distributed over all of the scenes to be corrected.

Chip Channels

The number of the channels in the chip database to use for automated ground control point (GCP) matching.

Chip Matching Algorithm

The algorithm used for automated ground control point (GCP) matching.

Available options are:

The distance in the x and y directions from a starting location on the reference image over which the search for the best match with a fixed point on the input image is conducted.

The search radius is an estimation of error with the raw image's positional information and the accuracy of the digital elevation model (DEM). For example, if you know your image is accurate to within 80 meters and your DEM is accurate to within 200 meters, set the search radius to 280 meters. A larger search radius requires more processing time, due to more locations being evaluated to determine the best match for a ground control point (GCP).

If no value is specified for this parameter, the module uses the same value specified for the Search Radius parameter.

Chip Minimum Score

The threshold value that controls whether a candidate ground control point (GCP) is accepted or rejected as a GCP. This parameter specifies the minimum match quality that is considered an acceptable match, with 1.0 indicating a perfect match.

When using the Fast Fourier Transform Phase matching algorithm, this value is converted internally to a minimum acceptable phase shift peak value.

When using the Normalized Cross-Correlation matching algorithm, this value specifies the minimum match score value required to accept a local match between the input and reference images as a GCP. The system default value is 0.75.

Road Network

The path to a vector file that contains the road-network layers to use for automatic collection of ground control points (GCP).

GCP collection from the road network extracts GCPs by matching an optical image with rasterized lines.

The GCPs are collected automatically by matching patches in the image with roads. Matching is performed in the spatial-frequency domain using Fast Fourier Transform (FFT) to transform and match image patches and rasterized lines. The matching algorithm is based on the Kuglin and Hines (1975) paper cited in the References section later in this topic.

In a typical application, between 100 and 200 GCPs are extracted, with most of them being correct. The GCPs can then be used in automated image-orthorectification workflows. This method is well-suited to midresolution images from 5 meters through 15 meters.

Road Width Field Name

The field name of an attribute in the vector segment. The field must contain one or two numerical values. The values are converted to a line width, in meters. Float, double, and integer fields are supported.

If this parameter is not specified, then the following field names are checked:

If none of these fields exist, then the Road Width Scale & Offset parameter defines the width of all lines in the file.

If the field does exist, and it contains a single value, then the scale factor part of the Road Width Scale & Offset parameter is used in the computation of the road width:

If the field exists, and it contains two values, then the two values in the Road Width Scale & Offset parameter are used to compute the road width:

Road Width Scale & Offset

The scale and offset, in meters, used in conjunction with the Road Width Field Name parameter to compute the road width in meters. This parameter contains one or two values. The first value, the road width scale (roadWidthScale), must be greater than zero. If specified, the second value, the road width offset (roadWidthOffset), must be non-negative.

If no value is specified for the Road Width Field Name parameter, the road width scale defines the width of all lines (in meters) in the file and the second value is ignored.

If a value for the Road Width Field Name parameter is specified, the scale and offset values are used to convert attribute values in the field to road width values, in meters. For more information, see the description of the Road Width Field Name parameter.

Polygon Vector File

The path to a file containing the polygon layers to be used for automatic collection of ground control points (GCP). The path may also specify a folder containing multiple polygon files.

Note: In general, geo-morphologically stable lake and river polygon layers can be used as reference for GCP collection.

GCP Text Files

The path and file name of a text file, or a folder of text files, that contains ground control points (GCPs) from other sources.

Each text file must have the MAPUNITS parameter specified in its required format. You can also specify up to two additional parameters, ELEVREF, and ELEVUNIT. The following table shows the supported values, a description, and an example for each parameter.

Parameter Supported values Description Example
MAPUNITS PIXEL Pixel and line MAPUNITS=PIXEL
  UTM Universal Transverse Mercator MAPUNITS=UTM 32 T D000
  SPCS State Plane Coordinate System MAPUNITS=SPCS
  LONG/LAT Longitude and latitude MAPUNITS=LONG/LAT D000
  METER Image along-row and along-column, in meters MAPUNITS=METER
  FEET Image along-row and along-column, in feet MAPUNITS=FEET
ELEVREF MSL Mean sea level ELEVREF=MSL
  ELLIPS Ellipsoid ELEVREF=ELLIPS
ELEVUNIT METER Meters ELEVUNIT=METER
  US_FEET U.S. feet ELEVUNIT=US_FEET
  FEET Feet ELEVUNIT=FEET

When the path points to a folder, each text file must follow a naming convention, <filename>*GCP.txt, where <filename> is the file name of the ingested image.

For example:

GCP Text File Format

The format of the file or files specified for the GCP Text File parameter, if specified.

Note: Your GCPs must be the same units as the map units (MAPUNITS) in the text file you specify.

The available formats, including a link to an example of each, are as follows.

Format Example
2D: ID P L X Y S
2D: ID P L X Y S Sample 2D GCP file
2DERR: ID P L X Y eP eL eX eY S
2DERR: ID P L X Y eP eL eX eY S Sample 2DERR GCP file
3D: ID P L X Y Z S
3D: ID P L X Y Z S Sample 3D GCP file
3DERR: ID P L X Y Z eP eL eX eY eZ S
3DERR: ID P L X Y Z eP eL eX eY eZ S Sample 3DERR GCP file
Bulk GCP File
Bulk GCP File Sample bulk GCP file
Note: The standard formats support only points from a single image in each text file. The Bulk GCP File format includes all GCPs from a group of images in a single text file.

Water Mask File

The path to a file that contains the polygon water-mask layer to be used for refinement of ground control points (GCPs). The path can also specify a folder that contains multiple water-mask files.

Refine GCPs

Selected by default, this check box controls whether to refine the ground control points (GCP). Refinement is to systematically eliminate GCPs that have large errors. To retain the integrity of the GCPs you have imported or otherwise referenced in a text file associated with the project, clear the Refine GCPs check box.

Rejection Method

The method used to reject ground control points (GCP).

Available options are:

You can specify various values for this parameter, depending on the method selected.

Rejection Method Thresholds

The rejection threshold values for the value selected for the Rejection Method parameter.

This parameter is defined using two values (THRESH1, THRESH2); these differ in meaning depending on the selected rejection method:

Maximum GCPs

The maximum number of ground control points (GCPs) to accept.

After the module performs an initial collection of GCPs using the reference data, it refines the collection to ensure that only the most accurate points are retained.

If there are more GCPs collected than the specified maximum value, the module performs a second refinement, keeping only the GCPs with the lowest RMS error, up to the specified maximum number of GCPs. The second refinement uses the following rejection method:

RMS Error: for the second refinement, the rejection threshold value is set to the specified Maximum GCPs value.

Minimum GCPs

The minimum number of ground control points (GCPs) to accept.

After the module performs an initial collection of GCPs using the reference data, it refines the GCPs, and then verifies that the number of remaining GCPs is greater than or equal to the minimum number of GCPs.

When there are fewer GCPs remaining than the specified minimum value, the module performs a second refinement of the original GCPs, using less stringent rejection-threshold values. These values, specified for the Rejection Method Threshold parameter, differ based on the value selected for the Rejection Method parameter:

If there are still too few GCPs after the second refinement, the module aborts and displays an error message.

Collect Tie Points

Select this check box to collect tie points (TP) on valid overlapping scenes.

Sampling Method

The method to use to create tie-point samples from the source imagery.

Available options are:
The Susan and Grid options determine how to find the initial candidate positions in one image (the source image) for collecting sample points. The function builds a patch around each candidate position that it searches for in overlapping images.

For tie-point collection, the Susan option is often preferred because it facilitates performing quality assurance on the collected tie points: you can visualize a recognizable feature (perhaps a building corner or specific tree, for example) and compare it with the other image to see if it matches correctly.

TP Samples

The maximum number of tie points to collect.

Note: The tie-point-collection process may result in a higher or lower number of tie points than specified.

When using the Grid option, acceptable values are:

When using the Susan option, available values are:

Trials per TP

The maximum number of attempts to find a match. The module attempts to match the primary sample point and, if that fails, selects alternate points within the same grid cell until a match succeeds or the number of trials is reached. The value you specify must be an integer ranging from 1 through 500.

Distribution Area

The area of each image in which to distribute tie points (TP).

You can select from the following:

Matching Algorithm

The algorithm to use for automated point matching.

Available options are:

When the two images being matched have similar gray values and appearances, Normalized Cross-Correlation (NCC) generally produces acceptable results. When there is a rotation or image-size error in the initial math models, NCC may produce better matching results than FFTP. Typically, NCC also generates faster results, because the template size it uses is smaller than that used by FFTP.

For more consistently accurate results, FFTP is recommended. This method uses a larger template size than NCC and, because it works in the frequency domain, it looks at the patterns of details in the image rather than the gray values in a small neighborhood, which NCC uses. This makes FFTP more robust than NCC when there is a large difference in brightness between images or when a major land-use change has occurred between the images. FFTP also allows for a better match between images of the same area from different sensors or spectral bands.

Matching Channels

The channel or channels in the image file from which to extract the TPs.

When this parameter specifies multiple channels, the channel data is averaged together. If no value is specified for this parameter, its value defaults to channel 1.

The maximum search radius, in pixels, for TPs. This controls the size of the area to search when seeking a match. A higher value increases the search area to be considered while matching each point, thereby increasing the processing time. Pixels in the search area is inspected for similarity within a small window (template) from the raw image. The pixel with the highest degree of similarity is accepted if it passes the match-acceptance criteria. The specified value should be slightly greater than the expected inaccuracy of registration between the two images, due to all possible causes. For example, if the nominal model of a satellite image is known to be accurate to approximately 100 pixels, and DEM inaccuracies can add another 30 pixels, then the search radius should be set to about 150 pixels. The poorer the accuracy of the initial match location estimate, the larger the search radius should be.

TP Minimum Score

The minimum-acceptance value for the correlation score that is considered to be a valid match. Valid values range from 0 to 1. For a match to become a TP, its match score must be greater than the specified value.

TP Rejection Method

The method used to reject tie points (TP).

Available options are:

You can specify various values for this parameter, depending on the method selected.

TP Rejection Method Thresholds

The rejection threshold values for the value selected for the Rejection Method parameter.

This parameter is defined using two values (THRESH1, THRESH2); these differ in meaning depending on the selected rejection method:

Pansharpen Order

The order in which to perform pansharpening.

Available options are:

Pansharpening Method

The method to use for pansharpening.
Available options are: With either method, both 8-bit and 16-bit data types are supported, and the images can be from the same or different sensors.

Multispectral Sharpening Channels

A comma-delimited list of the multispectral channels to sharpen.

If no value is specified for this parameter, all channels are processed by default. These channels are fused with the high-resolution, panchromatic image data.

Note: You cannot specify duplicate channels.

Multispectral Reference Channels

A comma-delimited list of the multispectral channels to use as reference for the sharpening process.

If no value is specified for this parameter, all channels are processed by default. These channels, and those of the panchromatic image, span the same range of frequency (wavelength) response.

When no reference channel is specified, the module determines the appropriate reference bands based on the available wavelength information for both the panchromatic and multispectral files.

Note: You cannot specify duplicate channels.

Resampling Method

The resampling method to use during processing.

Available resampling options are:

Enhance

Specifies whether to generate a refined pansharpened image.

The enhance option is only available for UNB pansharpening.

Edge Sharpen

Amount of sharpening to image edges to apply. A value of 1.0 (default) means no edge sharpening. Values greater than 1.0 apply greater sharpening. Values greater than 2.0 are not recommended.

Applying edge sharpening makes image more visually appealing but may degrade radiometric similarity with the original multispectral (MS) data.

AdaptRadiometry

Method to adapt the output spectral values to those of the input multispectral (MS) image.

Adapting the radiometry can better match to the original multispectral image. The two methods are linear regression based on a small sliding window and an estimate of the Modulation Transfer Function (MTF).

Available options are:

Output Map Units

The projection of the output imagery.

The value of this parameter must be in the PCI Projection String format.

The standard definitions are:

If you do not specify a value for Output Map Units, the map unit of the input image is used for the output image. If the input data is a variety of map units, the map unit of each output image is that of its corresponding input image. In such a case, it is recommended that you specify the output map units.

You can also specify the label of a projection defined in the userproj.txt file.

Panchromatic Pixel Output Size

The output spatial resolution for the panchromatic imagery to be orthorectified.

The units for the pixel size must match the units selected for the Map Units parameter; for example, if the map units are specified as UTM, the panchromatic pixel output size is in meters.

If no value is specified for this parameter, the pixel output size is based on the input math model associated with each scene in the input-scenes folder.

Note: If the input files have been pansharpened previously, specify the output pixel size in the Multispectral Pixel Output Size parameter.

Multispectral Pixel Output Size

The output spatial resolution for the multispectral imagery to be orthorectified.

Note: When the input images have been pansharpened previously, use this parameter to specify the output resolution.

The units for the pixel size must match the units specified for the Map Units parameter; for example, if the value of Map Units is specified as UTM, the multispectral pixel output size is in meters.

If no value for this parameter is specified, the pixel output size is based on the input math model associated with each scene in the input-scenes folder.

Resampling Method

The resampling method to use during processing.

Available resampling options are:

Resampling Method Extra Options

When you specify a value for the Resampling Method parameter, you can use the Resampling Method Extra Options parameter to specify additional options. The available options are specific to the following resampling methods:
Note: With each resampling method, the parameters MIN=[min], MAX=[max], and FILL=[NN or BGD] can be appended as a comma-delimited list. MIN and MAX define the clamp range for output pixels. This is useful when you want to keep pixel values within a certain range; for example, 1 to 2047 if 11-bit data is stored in a 16-bit file. FILL defines the behavior when the resampling window contains NoData pixels: NN instructs the resampler to use the Nearest Neighbor method, while BGD indicates that the output pixel is set to the background value. By default, NN is used for FILL.

Sorting Method

The order in which the images is sorted and added to the mosaic.

Available options are:

Starting Image

When you select Nearest to Center or Maximum Intersection for Sort Method, the first image to add to the mosaic.

If you do not specify a starting image, the image that is most central is processed first.

When you select None for Sorting Method, this parameter is ignored.

Normalization Method

The normalization to apply to each source image before color balancing, cutline generation, or mosaicking.

The available normalization methods are as follows:

Normalization Method Extra Options

When you select Adaptive for Normalization Method, you can define additional options for normalization.

To define the filter size for the adaptive normalization, enter the image_percent value to use

The default is 20 (20 percent).

Color Balancing Method

The color-balancing method to apply to the final mosaic.

Color balancing evens out the color contrasts from one image to another to reduce the visibility of the seams and produce a visually appealing mosaic. All color-balancing methods (except None) result in some parameters that define an adjustment of pixel values in the source image. The adjustments are applied when the image is added to the mosaic and stored as part of the mosaic project.

The available color-balancing methods are as follows:

Color Balancing Extra Options

Additional color-balancing options. The options apply to the Bundle, LUT, Histogram, Reference, and Neighborhood color-balancing methods.

The available options, based on the color-balancing specification, are:

Global Color Balance Mask File

The file used to define a global color-balance mask, which identifies regions in the source images to omit from any color-balancing computation.

A global mask is useful when imagery contains, for example, massive water bodies. The global color-balance mask applies to all images in the mosaic project.

If you specify a value for this parameter, you must specify a value for Global Color Balance Mask Layer.

Global Color Balance Mask Layer

The layer in file specified for Global Color Balance Mask File that contains a global color-balance mask identifying regions in the source images to omit from any color-balancing computation.

Available options are:

Global Color Balance Mask Segment

When Specific Segment is selected for Global Color Balance Mask Layer, this parameter specifies the number of the segment that contains polygons or bitmaps to use to mask pixels during color-balancing calculations.

Cutline Method

The cutline method used to generate polygons that enclose all the data from an image to be included in the output mosaic.

Supported methods are:

Cutline Method Extra Options

Additional options for Cutline Method.

You can specify options related to constraining polygons, which define regions where cutlines are allowed for each image, so that the generated cutlines do not cross the specified boundaries.

Values you specify for this parameter take precedence over Auto Constrain and Factor.

With all options for Cutline Method, except File Extents, you can constrain the cutlines by specifying the following extra options:
[<vector_file>], [<field_name>], [<segment_number>]
Where:
The values in the attribute field, field_name, must correspond to the identity of one input source image. An input source image's identity is determined by:
  1. the value of its file level metadata tag: SourceID, or if that tag does not exist, then
  2. the base name, without the extension, of the input source image's file name.

If the field_name is not specified, MOSPREP searches the vector-segment attributes for a field named ImageSource. If the specified field name or ImageSource does not exist, an error occurs.

If the segment number is not specified, the algorithm uses the last segment from the vector file you specified. If the constraining polygon is larger than the image being processed, cutline generation is not constrained.

Auto Constrain

Select whether and how to automatically generate and apply constraint polygons when creating cutlines. Constraint polygons define regions where cutlines are allowed for each image, so that the generated cutlines do not cross the specified boundaries. You can opt to have them generated automatically based on the layout and arrangement of the images being mosaicked.

You can select from:

You can adjust the effect of Auto Constrain by specifying an appropriate percentage value for Factor.

When a constraining layer is specified for Cutline Method Extra Options, do not use Auto Constrain; that is, select No.

Factor

The Factor is a percentage by which to adjust effect of the Auto Constrain option.

This is a value between 1 and 100, with larger values causing more overlap between the generated constraint polygons; that is, the cutlines is less constrained.

Simplify Cutlines

Selected by default, this check box causes the module to simplify the cutlines for the mosaic. Simplification is to remove unsuitable vertices from the cutline shapes computed initially.

You can use this parameter in conjunction with Simplification Level to set the degree of simplification you want.

Simplification Level

Available when the Simplify Cutlines check box is selected, you can set the level of simplification you want to use.

When the Simpify Cutlines check box is clear, no simplification level is applied. When the check box is selected, a default value of 1.75 for Simplification Level is applied; otherwise, the value you specify is applied.

To create cutlines from all of the vertices computed initially, enter a value of 0. A number greater than zero increases the amount of vector reduction; the cutlines will have fewer vertices. Generally, a value of n results in 1/n of the vertices being computed. For example, a value of 2 results in approximately one half of the vertices.

Global Cutline Avoidance Mask File

The file that, in conjunction with Global Cutline Avoidance Mask Layer and Global Cutline Avoidance Mask Segment, can be used to identify common regions in all source images to omit from cutline calculations. When a global cutline-avoidance mask is used, the image pixels in the masked regions are excluded from the cutline calculations wherever possible; if there is no better area in which to place a cutline, the cutline passes through the masked region.

When you specify a value for this parameter, you must also specify a value for Global Cutline Avoidance Mask Layer.

Global Cutline Avoidance Mask Layer

The layer in the file specified for Global Cutline Avoidance Mask File to use as the global cutline-avoidance mask. When no value is specified for Global Cutline Avoidance Mask File, this parameter is ignored.

Global cutline-avoidance masks are used to restrict specific areas from cutline calculations; for example, to avoid cutlines crossing through buildings. When a global cutline-avoidance mask is used, the image pixels in the masked regions are excluded from the cutline calculations wherever possible; if there is no better area in which to place a cutline, the cutline passes through the masked region. A global cutline-avoidance mask applies to all source images that intersect the global mask layer.

Available options are:

Global Cutline Avoidance Mask Segment

When Specific Segment is selected for Global Cutline Avoidance Mask Layer, this parameter specifies the number of the segment that contains polygons or bitmaps to use to mask pixels to avoid when calculating cutlines.

Area of Interest File

A file that contains a single vector layer that defines the area to which the output mosaic is clipped.

The vector layer can contain one or more polygons.

Crop Tiles to AOI

Selected by default, this check box controls whether to crop the tiles to the area of interest (AOI) during processing.

Tile Base Name

The base name for file names of all tiles created during the mosaicking process.

Note: The value for this parameter cannot be the same as that of Input Scene File.

Tile Specification

The tiling scheme to use for the output mosaic.

Available schemes are:

Height

The height of the mosaic tile, in pixels.

The union of the extents of all of the source images is divided into a series of evenly sized and abutting rectangular tiles with the specified dimension.

Only tiles that actually intersect at least one of the source images is present in the output. The tiles at the far right and on the far bottom may overhang the extents of the source images. This is done to ensure that all tiles have the same dimensions.

TileID values are generated using the convention <column_number>_<row_number>. For example, the upper-left tile always has a TileID of "1_1", while the one immediately below it is "1_2", and so on.

For example:

10000

Width

The width of the mosaic tile, in pixels.

The union of the extents of all of the source images is divided into a series of evenly sized and abutting rectangular tiles with the specified dimension.

Only tiles that actually intersect at least one of the source images is present in the output. The tiles at the far right and on the far bottom may overhang the extents of the source images. This is done to ensure that all tiles have the same dimensions.

TileID values are generated using the convention <column_number>_<row_number>. For example, the upper-left tile always has a TileID of "1_1", while the one immediately below it is "1_2", and so on.

For example:

10000

Vertical Overlap

The vertical overlap of each tile, in pixels.

Note: The Width parameter value is considered sacrosanct and is always honored. Thus, setting the Vertical Overlap to something other than zero causes the mosaic tile positions to be adjusted, rather than changing the tile widths.

Horizontal Overlap

The horizontal overlap of each tile, in pixels.

Note: The Height parameter value is considered sacrosanct and is always honored. Thus, setting the Horizontal Overlap to something other than zero causes the mosaic tile positions to be adjusted, rather than changing the tile heights.

Tile File

The name of the text file containing the tile-definition layer.

Each line in the text file contains five elements separated by spaces: the first two define the upper-left coordinate in the x and y dimension, respectively. The next two define the lower-right coordinate in the x and y dimensions, respectively. The last one specifies the output file name of the tile. If the file name includes an extension, the extension is removed when the value is stored as the 'TileID' attribute in the tile-definition polygon. If the file name includes a path, the entire path is transferred and appended to the output folder.

The values specified in the text file can be in one of these coordinate types:

The RASEXT and RASOFFSZ coordinate types make use of pixel/line raster, as defined by the union of the extents of all input source images. If a coordinate type is not specified, it is assumed to be GEOEXT. For example:

Segment Number

In the tile file you specified, the number of the vector segment to use. If no segment number is specified, the last segment in the specified tile file is used.

Field Name

Name of the field (attribute) that has unique identifiers for each tile. The module uses the values in the field to form the names of the mosaic tile files. If no field name is specified, the attribute ShapeID is used.

Coordinate Type

When Tile Specification is Script File, the type of coordinates in the script.

You can select from the following:

Tile Position Transformation

With this parameter you can define a grid where each top-left corner of a tile is aligned to one of the vertices in the grid.

You specify this parameter by entering a keyword and either two or four values. The keyword indicates the relative positioning of the values:
After specifying the keyword, the general form of the remaining values is:

These values define the position of the corner or center in the raster grid.

Of the four values, only Stride_X is required. If not specified, Stride_Y defaults to the Stride_X value, and Ref_X and Ref_Y default to zero.

In the following example, the upper-left corner of the upper-left pixel of each tile is an even 20-meter multiple from the reference point (432345.000, 5438882.000). Depending on the distance of the tile from that point, its upper-left corner coordinate could be 432345.000, 432045.000, or any other multiple, but is never 432346.000 or 432355.000.

Example:

"CORNER, 20, 20, 432345.000, 5438882.000"

If specified, this parameter is applied in all scenarios, whether the image-corner coordinates come from the input file (MFILE), ULX and ULY, or through automatic computation.

Blend Width

The perpendicular distance from the cutlines over which image blending occurs.

Image blending is to average the gray value of each pixel in the blending strip along a cutline from both overlapping input images. If no value is specified for this parameter, no blending is performed.

Create Source Map

Select this check box to create a source map on output along with the mosaic.

A source map is a polygon layer created and stored in a separate file, which contains an attribute that identifies the predominant source input image used for each pixel in the output mosaic. As images are added to the mosaic, the source image is recorded in a separate raster, which is converted to a polygon layer at the end of the process.

The polygon layer contains three attributes (fields):

The source map layer is created in a file with the same name as the output mosaic file(s), but with _SourceMap.pix appended to it.

Existing Tile Rule

Select an action to perform when an output tile already exists.

Available options are:

Delete Empty Tiles

Select whether to delete empty tiles. A tile is considered to be empty if all pixels in it have the value defined as NoData.

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Details

General job details

Preprocessing requirements

Before running this module, the following requirements must be met to ensure the job processes successfully and produces accurate results:

Module details

The Mosaic from Raw Scenes module imports satellite imagery into CATALYST Enterprise for processing and produces output mosaic images.

For each scene contained in the input-scenes folder, the module spawns the following child jobs:
  • Data Ingest: to import the imagery into the CATALYST Enterprise system
  • GCP Collection: to automatically collect ground control points
  • Tie-Point Collection (if selected): to collect tie points
  • Pansharpening (if selected): to merge panchromatic and multispectral image pairs to create a single, high-resolution color image
  • Orthorectification: to correct distortions in the raw image using a math model and digital elevation model (DEM)
  • Mosaic Preparation: to perform the necessary preprocessing of the scenes to be mosaicked
  • Mosaic Generation: to assemble the various input source images into a continuous, seamless mosaic image

About GCP collection on road vectors

This module extracts ground control points (GCPs) by matching an optical or SAR image with rasterized lines.

The module is designed to extract GCPs from road vectors in medium-resolution images with resolutions from about 4 meters through 15 meters. It models each road as a ribbon with a sinc-like cross-section. The ribbon is either dark on a uniform bright background, or bright on a dark background. The width of the ribbon is either set explicitly or derived from attributes of each road segment, such as the number of traffic lanes.

This model works very well for mid-resolution images, such as SPOT and Landsat 7 PAN, and provides GCPs accurate to about 1 pixel, or within 5 meters through 10 meters. PCI extended to higher-resolution images by averaging the images down to the matching resolution of 3 meters through 6 meters. The matcher can also be directed to try both bright-on-dark or dark-on-bright matches at every point, and then select whichever one is better.

The enhanced process extracts a sufficient number of GCPs, but their accuracy is still at the 5-meter through 10-meter level. This is due to several factors:
  1. Inherent accuracy of road vectors

    This factor alone limits the achievable accuracy of GCPs extracted from road vectors. Canadian experience shows that most road vectors have an accuracy of about 5 meter through 10 meter; for example, the current Canadian national road network claims an accuracy of 6.5 meters. In addition, many road vectors are less accurate, or even in disagreement with the images, due to rapid land-use changes in many areas. The road GCP module can even cope with large inaccuracies, or fail for such GCPs, but the overall achievable accuracy is limited.

  2. Road model used

    The "smooth-ribbon" model is well suited to mid-resolution images, particularly in non-urban areas. However, it becomes inadequate at higher resolutions due to other details in the images, such as vehicles, street furniture, road markings, vegetation, and building and tree shadows. Objects such as these introduce significant clutter, and lower the overall accuracy of the matches. These matches are often rejected. If they are not rejected, the matcher settles on nearby, more uniform linear objects, such as bright rooftops of large buildings or their shadows.

  3. Varied appearance of roads

    The roads may not be uniformly brighter or darker than their surroundings, as the model assumes. Their appearance depends on the spectral bands of the matched image, type and age of the road-surface material, season (snow versus no snow), and even the moisture content. In many images, roads are mid-gray, and, in such a case, are not handled well by the tool.

  4. Significant building lean in urban scenes

    High-resolution satellites fly at lower altitudes and, therefore, introduce a higher degree of building lean. Some images can also be taken in off-nadir orientation, which magnifies this effect even more. In urban areas, leaning buildings often obscure streets, at which point the matcher either fails or matches incorrect features.

  5. Elevated highways

    In most instances, the elevations of GCPs are extracted from a bare-earth digital elevation model (DEM), while some of the GCPs can be extracted from elevated highways, bridges, or multilevel highway intersections or interchanges. Such features are matched correctly in the image space, but have incorrect (ground) elevations, which leads to biased GCPs and an inaccurate refined model.

All of the preceding factors contribute to the lowered accuracy of road GCPs in high-resolution images, and limit their accuracy to the 5-meter through 10-meter range. They also introduce a possibility of systematic biases, particularly along the viewing direction of the satellite.

Road GCPs extracted from high-resolution images are still useful if the biases in the original (nominal) model of the scene exceed 10 meters through 5 meters. However, if the nominal model is already accurate to greater than 10 meters, the model refined with the road GCPs may be less accurate than the nominal one.

Images with resolutions outside the optimum range will be processed, but the results may be unsatisfactory: few extracted GCPs for low-resolution images, and many incorrect matches for high-resolution images. The module issues a warning for images with pixel sizes less than 1.9 meters.

Naming convention for GCP IDs

Each GCP collected has an ID. The naming convention of the ID is described in the following table, where the GCP ID is: XXXXXXXX_YYYY_N.

GCP ID element Description
XXXXXXXX Hash code of the input image
YYYY Hash code of the reference data
N Number of the GCP, one to any number
Restriction: When running this module on a Linux operating system, do not use circular symbolic links, because this will cause the job to loop continuously. For example, when you ingest the contents of folder /abc, make sure the following does not exist:

Job results

For each raw scene found in the input scenes folder, the Mosaic from Raw Scenes module creates a series of output files in the subfolders of the specified output folder, depending on the options specified for the module parameters. For example, if you specified tiled output, the output folder will contain the mosaicked result in a series of tile files. The file names for the tiles are created automatically according to the specified base name and location or vector-file field name.

Depending on the specified options, this module creates the following subfolders and files:
  • ingest_gcp: contains the results from the Data Ingest and GCP Collection module; files are used as input for collecting tie points, orthorectification, or pansharpening workflows
  • tiepoint: contains the results from the Tie-Point Collection and Refinement module; files are used as input for orthorectification
  • ortho: contains the results from the Orthorectification module; files are used as input for pansharpening or mosaic-preparation workflows
  • pansharp: contains the results from the Pansharpening module; files are used as input for mosaic preparation or orthorectification workflows
  • mosprep: contains the results from the Mosaic Preparation module; files are used as input for mosaic generation
  • mosgen: contains the results from the Mosaic Generation module
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References

Kuglin, C.D. and D.C. Hines (1975). "The phase correlation image alignment method." Proceedings of the IEEE 1975 International Conference on Cybernetics and Society, San Francisco, California, 163-165

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