Orthorectification using Building Models module

Name	Caption
Send Email	Email notification settings
Input Scenes	Input folder
Output Folder	Output folder
Output File Type	Output file type
Output File Options	Output file options
Overwrite Results	Overwrite existing results
Source Background Type	Source background type
Source Background Value	Source background pixel value
Output Background Value	Output background value
DEM Source	DEM tile source
DBM Source	Source of digital building model
DBM Elevation Reference/Datum	Elevation model
DBM Units	DBM elevation units
DBM Vector Layer	DBM vector layer
Artifacts to Correct	Type of artifact to correct
Fill Voids of Any Size	Fill voids of any or specific size
Void Threshold	Threshold to fill voids using interpolation
Smear-Classification Ceiling	Level of smear classification to correct
Smear-Area Threshold	Minimum area of smearing to correct
Output Map Units	Output projection
Output Pixel Size	Output pixel size
Edge Clip	Percentage to clip edges
Resampling Method	Resampling method
Resampling Method Extra Options	Extra options for resampling method
Occlusion Buffer Size	Size of occlusion buffer
Radiometric Difference	Radiometric difference between the ortho being processed and the candidate images

Parameter descriptions

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.

Input Scenes

The path and name of the folder containing raw images that include a valid math-model segment. Images in this folder must have been processed previously with one of the modules in the following table, depending on whether points have been collected.

When	Specify Input Scenes as
No points have been collected	Path and name of the output folder of the Data Ingest module
Only ground control points (GCPs) have been collected	Path and name of the output folder of the GCP Collection module
Only tie points (TP) have been collected	Path and name of the output folder of the Tie-Point Collection and Refinement module
Only GCPs and TPs have been collected	Path and name of the output folder of the Tie-Point Collection and Refinement module

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

Path and name of a folder of input images; for example, C:\data
Path and name of a folder containing an OrthoEngine project file; for example, C:\data\data-ingest_RAW_PAN.prj
Path and name of a folder with a wildcard to filter the imagery by file name or type; for example, C:\data\*_PAN.pix
Path and name of a folder path with a wildcard to filter by OrthoEngine project file; for example, C:\data\*_PAN.prj
You can also specify an MFILE as input. An MFILE is a text file with an .mfile file name extension. For more information on this type of file, see About the MFILE format.

Output Folder

The path and name of the folder in which to write the output orthorectified image scenes.

Output images are created using a file name generated automatically that includes the image scene, state, and image type.

Note: When the output folder is on another computer on your network, the orthorectified imagery is created temporarily in a local temporary folder, and then copied to the specified output folder; the local copy is then deleted.

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.

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:

File Metadata, else None: reads the NoData value from the input-file metadata. The module first checks for the file-level metadata tag NO_DATA_VALUE in the source raster. If the tag is present, this value is used as a default for all channels in the file. Next, the module checks for channel-level NoData tags; if one is found, the channel-level value overrides the file-level value for that channel.

If there are channel-level NoData tags, but no file-level tag, a pixel is considered as NoData if each of the channels with a NoData tag corresponds to its NoData value. In this case, channels without a NoData tag are ignored when identifying background pixels.

If the file does not contain NoData tags, all pixels in the source image are considered valid.
None: all pixels in the source image are to be considered valid
All: if the pixel value in all channels matches the values provided for the Source Background Value parameter, the pixel is considered background (NoData).
Any: if the pixel value in any channel matches the value provided for the Source Background Value parameter, the pixel is considered background (NoData).

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:

Source Background Type set to All and Source Background Value set to 0: a pixel is considered background if all three channels are zero.
Source Background Type set to Any and Source Background Value set to 0: a pixel is considered background if any of the three channels is zero
Source Background Type set to All and Source Background Value set to 128,0,0: a pixel is considered background if its value is exactly 128 for the first channel and zero for the second and third channels
Source Background Type set to All and Source Background Value set to 128,0,0,245: a pixel is considered background if its value is exactly 128 for the first channel and zero for the second and third channels. The value 245 is ignored.
Source Background Type set to Any and Source Background Value set to 128,0: a pixel is considered background if the value in channel 1 is 128 OR if the value in channel 2 or 3 is zero.
Source Background Type set to Any and Source Background Value set to 1032,0: a pixel is considered background if the value in channel 1 is 255 OR if the value in channel 2 or 3 is zero. The first value is truncated to the range allowed for 8U data.

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:

Name of a single DEM file; for example, C:\data\DEM\dem.pix
Name of a folder containing one or more DEM tiles and an associated index.txt file; for example, C:\data\DEM
Name of an index file; for example, C:\data\DEM\index.txt

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).

DBM Source

The name of a vector file that contains triangulated digital building models (DBM).

If this parameter specifies the name of a single file, you must select a value for the DBM Units parameter and specify a value for the DBM Vector Layer parameter.

If no value is specified for this parameter, the DBM Units and DBM Vector Layer parameters are ignored.

DBM Elevation Reference/Datum

The vertical reference for the elevation values in the source digital building model (DBM).

Available values are as follows:

Mean Sea Level: Elevations are referenced to mean sea level (MSL). The EGM2008 geoid model will be used to convert the elevations to ellipsoidal heights.
Ellipsoid: Elevations are referenced to the ellipsoid. The coordinate system of the DBM file is examined to determine which ellipsoid and datum to use. For example, if the DBM file is referenced to NAD83, the heights are assumed to be NAD83 ellipsoidal heights. If the DBM and math model are based on different coordinate systems, the heights are converted automatically to the math-model coordinate system before use.

DBM Units

The units of the elevation values that are stored as vertex z-coordinates in the input DBM, as specified in the DBM Source parameter.

Acceptable values are as follows:

Meters (default)
Feet
US Feet

Note: FEET is defined as 0.3048 meters (corresponding to International Feet); US_FEET is defined as 1200/3937 meters (corresponding to U.S. Survey Feet).

DBM Vector Layer

The number of the segment that contains the input DBM vector layer to process. The specified vector layer must contain three-dimensional triangles that represent building rooftops.

If no value is specified for the DBM Source parameter, the DBM Vector Layer parameter is ignored.

If a single file is specified for the DBM Source parameter, and no value is specified for the DBM Vector Layer parameter, the module uses the first vector segment in the file specified for the DBM Source parameter.

Artifacts to Correct

The types of artifact to correct: occlusions, smears, or both.

You can select from the following:

All: Corrects occlusions and smears.
Occlusions: Corrects obscured objects in ground space and, if they are visible in any overlapping images, fills them. If no images overlap, the voids remain and are filled by using interpolation.
Occlusions occur when the line of sight between the ground surface and the camera is obscured, it is not visible in the imagery.

Occlusion-correction is required to achieve "better orthorectified images."
Smears: Corrects smeared, or stretched, areas and replaces them with nonsmeared areas from overlapping images.
That is, when the line of sight between the ground surface and the camera has a high-incidence angle to the ground surface, the object appears at a lower resolution in the imagery.

Fill Voids of Any Size

Available when Artifacts to Correct is All or Occlusions, select this check box to use interpolation to fill voids of any size or of the size and above that you specify for Void Size.

That is, the Occlusions artifact-correction type can create voids that are not filled by using data from overlapping images. By selecting this check box (and, optionally, specifying an upper limit), any voids created are filled by using interpolation.

Void Threshold

The threshold, in pixels, at which to fill voids by using interpolation.

Smear-Classification Ceiling

When Artifacts to Correct is All or Smears, select a value at which to correct smearing, or stretching, by using pixels from overlapping images.

That is, smearing is corrected when a pixel has a classification less than or equal to the value you select.

Typically, smearing of the ortho pixels occurs in imagery acquired at an incidence angle of 20 degrees or greater. At an incidence angle of 50 degrees or greater, the smearing is severe.

Smearing has 14 classes of severity: the first four values (0, 1, 2, & 3) are addressed by the selected resampling method. The remaining 10 values—ranging from four through 14—indicate the smearing effect for each ortho pixel, where four is the severest and 14 is the least.

Smear-Area Threshold

The minimum area of the smearing to correct, in pixels.

Areas with fewer pixels than the value you specify are ignored.

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:

PIXEL: Pixel and line (not for use with DEM extraction)
UTM: Universal Transverse Mercator

The value specified can be the UTM grid zone number and row, and Earth model, as follows:
```
UTM [mm] [r] [Ennn]
```
where:
- [mm] is the two-digit zone number between 1 and 60
- [r] is the zone row: a single letter between N and X for north of the equator and between C and M for south of the equator. Zone rows A, B, Y, and Z are not supported; rows I and O do not exist.
- [Ennn] specifies the Earth model, where the model number is between 0 and 19. If the Earth model is not specified, it is assumed to be E000 (Clarke 1866).
SPCS: State Plane Coordinate System

The SPCS zone number and Earth model can be specified as follows:
```
SPCS [mmmm] [Ennn]
```
where:
- [mmmm] is the four-digit zone number
- [Ennn] specifies the Earth model, where the model number is between 0 and 19. If the Earth model is not specified, it is assumed to be E000 (Clarke 1866).
LONG/LAT: Longitude and latitude

The Earth model can be specified for LONG/LAT (and other units except PIXEL), as follows:
```
LONG/LAT [Ennn]
```
If the Earth model is not specified, it is assumed to be E000 (Clarke 1866).
EPSG: European Petroleum Survey Group code

You can specify the projection by entering an EPSG code defined by the Open Geospatial Consortium (OGC). For information on the code definitions, visit epsg.org and spatialreference.org.

The EPSG code is specified using the EPSG keyword followed by an integer and separated by a colon; for example:
```
EPSG:4326
```
Most common EPSG codes are supported.
METER: Image along-row and along-column meters
FEET: Image along-row and along-column feet
You can also specify the label of a projection you define, if the projection exists in the userproj.txt file; otherwise, you must enter the projection-parameter information as a string separated by the vertical bar (|). The projection-parameter string defines 18 parameters delimited by spaces, including the following:
- Dearth
- RefLong
- RefLat
- StdParallel1
- StdParallel2
- FalseEasting
- FalseNorthing
- Scale
- Height
- Long1
- Lat1
- Long2
- Lat2
- Azimuth
- LandsatNum
- LandsatPath
- UnitsCode
For example, the projection named 'France93' can be specified, as follows:
```
LCC D350 | 0 0 3.0 46.5 44.0 49.0 700000 6600000 0 0 0 0 0 0 0 0 0 -1
```

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.

Output Pixel Size

The sample size of the output imagery.

The output pixel size must be specified in the value (units) of Output Map Units; for example, when the value of Output Map Units is specified as a UTM zone, the pixel output size must be in meters. When the value is specified as Long/Lat, the pixel size must be in decimal degrees.

If a single value is specified, that value applies to both x and y values.

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 folder.

Edge Clip

The percentage to clip the edges of the image during orthorectification. The clip amount is applied to each edge of the orthorectified image. For example, a value of 5, clips five percent from the four edges.

With aerial workflows, surveys are often flown to ensure significant overlap between images to allow for correction of building lean. With this parameter, you can clip the along-track and across-track strips from the image to produce cleaner orthorectified images. Aerial images are always rectangular and oriented vertically or horizontally.

The maximum clip value is 49 percent.

Resampling Method

The resampling method to use during processing.

Available resampling options are:

Cubic: cubic convolution. This method determines the gray level from the weighted average of the 16 pixels closest to the specified input coordinates and assigns that value to the output coordinates. The resulting image is slightly sharper than one produced by bilinear interpolation, and it does not have the disjointed appearance produced by nearest-neighbor interpolation. This is the default value.
Nearest Neighbor: nearest-neighbor interpolation. This method identifies the gray level of the pixel closest to the specified input coordinates and assigns that value to the output coordinates. Although this method is the most efficient in computation time, it introduces small offsets in the output image. The output image may be offset spatially by up to half a pixel, which may cause the image to have a jagged appearance.
Bilinear: bilinear interpolation. This method determines the gray level from the weighted average of the four closest pixels to the specified input coordinates and assigns that value to the output coordinates. An image with a smoother appearance than nearest-neighbor interpolation is created, but the gray-level values are altered in the process, resulting in blurring or degraded image resolution.
Lagrange-4: four-point Lagrange interpolation
Lagrange-8: eight-point Lagrange interpolation
Sinc-8: eight-point sin(x)/x
Sinc-16: 16-point sin(x)/x
Average: Average resampler for creating downsampled products
Gaussian: Gaussian resampler
Median: Median resampler for creating downsampled products

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:

Sin(x)/x with an 8 x 8 window
Sin(x)/x with a 16 x 16 window
SHAPINGWINDOW=[sw],BETA=[beta]

where:

SHAPINGWINDOW specifies a window to attenuate the SINC coefficients to reduce resampling artifacts. The value can be KAISER, HAMMING, HANN, LANCZOS, PARABOLA, or NONE. SHAPINGWINDOW is optional; the default value is KAISER. BETA is applicable only when SHAPINGWINDOW is KAISER. SHAPINGWINDOW determines the shape of the KAISER window; a larger BETA value produces greater attenuation of the SINC coefficients. Its value can be between 1.0 and 10.0. BETA is optional.

Average
NUMCOLS=[nc],NUMROWS=[nr]
Median
NUMCOLS=[nc],NUMROWS=[nr]

where:

NUMCOLS and NUMROWS can be any value between 1 and 11.
Gaussian
DSFACTORCOL=[dc],DSFACTORROW=[dr]

where:

DSFACTORCOL is the fraction downsampling factor in col (>=1). If not specified, a default factor is computed automatically based on the output and input pixel sizes. DSFACTORROW is the fraction downsampling factor in row (>=1). If not specified, default to the value of DSFACTORCOL.

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.

Occlusion Buffer Size

The size of the buffer surrounding each occlusion before filling.

Typically, in collected imagery, building rooftops do not align exactly with the actual footprint of the building. If these building misalignments remain uncorrected, the edges of the rooftops will render incorrectly on the ground or vice versa.

This parameter is used to grow the occluded regions before they are filled with data from neighboring images. By doing so, the algorithm can compensate for small inaccuracies in the elevation data set. For example, with a specified value of 4, and the resolution of the ortho image is 0.5 meters, buildings with a positional shift of up to 2 meters is compensated correctly.

Radiometric Difference

The extent of radiometric difference between the ortho being processed and the candidate images; that is, the level at which to correct the radiometric difference in contrast and brightness.

You can select from the following:

Low: Images are similar in contrast and brightness.
Moderate: Images have minor variance in contrast and brightness.
High: Images have major variance in contrast and brightness.
Any: Images are the same in contrast and brightness.

Orthorectification using Building Models module

Description

Parameters

Parameter descriptions

Details