DEM Extraction ADS module

Name	Caption
Input Scenes	Input scenes folder
Output Folder	Output folder
Output DEM Base Name	Output DEM base name
Save Intermediate Files	Save intermediate files
Overwrite Results	Overwrite existing results
Send Email	Email notification settings
Output Pixel Size	Output pixel size
Custom Size	Custom size of output pixel
Output Map Units	Output projection
Extraction Interval	Pixel sampling interval
Elevation Reference/Datum	Elevation model
Elevation Unit	Elevation unit
Failed Pixel Value	Failed pixel value
Background Elevation	DEM background elevation value
Look Directions	Look directions to use
Bit Depth	Bit depth of pair
Cost Function	Cost function for SGM extraction method
Penalties	Penalty values for cost function
Segment Size	Threshold at which to eliminate segments
Semi-global Filter	Level of SGM filtering
Pattern Suppression	Suppress pattern blunders
Track Epipolar Lines	Whether to track epipolar lines
NCC Extraction Interval	Extraction interval for DSM
Clip Amount	DEM clipping
Clip Units	Clipping units
SGM Extraction Interval	Extraction interval for SGM
Create DTM from DSM	Create DTM from DSM
Output DTM Pixel Size	Size of pixel in output DTM
Filter Type	Filter to apply during conversion
Terrain Type	Type of terrain
Create DEM Mosaic	Create DEM mosaic
DEM-Mosaic Method	Method to create the DEM mosaic
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
Delete Empty Tiles	Whether to delete empty tiles
Clean Up Building Edges	Straighten building edges
Edge-Cleaning Filter Size	Size of edge-cleaning filter
Cutline Method	Cutline method
Cutline Method Extra Options	Cutline options
Auto Constrain	Constrain cutlines to image centers
Factor	Auto Constrain Factor value
Blend Width	Cutline blend width

Parameter descriptions

Input Scenes

The name of the folder that contains a valid CATALYST Professional OrthoEngine project file (oe.prj), valid GDB-supported images, or a text file of images to be processed.

When only a folder name is specified, the module processes all recognized .tif and .pix image files in that folder.

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\<file_name>.prj
Path and name of a folder with a wildcard to filter the imagery by file name or type; for example, C:\data\*.pix
Path and name of a folder with a wildcard to filter by OrthoEngine project file; for example, C:\data\*.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 to which to write the output files.

Output DEM Base Name

The base name of the output digital surface model (DSM) and digital terrain model (DTM) files. This name is prepended to all of the output DSM and DTM files.

If no value is specified for this parameter, the default digital elevation model (DEM) base name is dem.

Save Intermediate Files

Select this check box to save any supporting files created during processing.

By keeping the files, you can use them to analyze intermediate results and, if necessary, fix any minor issues. You can then restart the job without having to regenerate all the supporting data, thereby reducing processing time.

Note: Intermediate files can consume a large quantity of disk space, thus it is a good idea to delete them when they are no longer needed.

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.

Output Pixel Size

The size of the output pixel in the DSM being created and, if applicable, the DTM. The size of the output pixel can be created either as a multiple of the ground sample distance (GSD) or you can specify a custom size.

Select one of the following:

1 x GSD: create an output pixel that is the GSD multiplied by one.
2 x GSD: create an output pixel that is the GSD multiplied by two.
3 x GSD: create an output pixel that is the GSD multiplied by three.
4 x GSD: create an output pixel that is the GSD multiplied by four.
5 x GSD: create an output pixel that is the GSD multiplied by five.
10 x GSD: create an output pixel that is the GSD multiplied by 10.
Custom: specify a custom pixel size with the value of the Custom Size box and, if necessary, the unit of measurement in the Output Map Units box. That is, you need only specify the map units if you are changing the projection of the output imagery. For more information about setting up a custom output pixel size, see the description of Custom Size and Output Map Units, respectively.

Custom Size

Available when you select Custom for Output Pixel Size, the custom pixel size of the output DSM, DTM, or both.

For example, when Output Map Units is UTM, the output pixel size must be in meters. With Long/Lat, the output pixel size must be in decimal degrees.

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.

Extraction Interval

The number of image pixels between the image locations at which an elevation value is computed, in both the along-row and along-column dimensions. The digital elevation model (DEM) cell dimension will approximate to the ground-projected pixel dimension of the image data multiplied by this value.

The available options are an Automatic option and values 1 through 32.

Although a higher value for this parameter causes the DEM to have a larger cell dimension and a lower level of detail, this also allows the DEM to be computed more quickly. The Automatic option determines the extraction interval based on the average resolution of the input imagery and the specified output DEM resolution.

Elevation Reference/Datum

The vertical reference for the elevation values in the source digital elevation model (DEM), or for the constant value of the Elevation Offset and Elevation Scale parameters, when available, and specified.

Available values are as follows:

Mean Sea Level: Elevations are referenced to mean sea level (MSL). The EGM2008 geoid model is used to convert the elevations to ellipsoidal heights.
Ellipsoid: Elevations are referenced to the ellipsoid. The coordinate system of the DEM raster file is examined to determine which ellipsoid and datum to use. For example, if the DEM file is referenced to NAD83, the heights are assumed to be NAD83 ellipsoidal heights. If the DEM and math model are based on different coordinate systems, the heights are converted automatically to the math-model coordinate system before use.
Automatic: Select this option when you want the module to automatically determine the elevation reference based on your input data. The DEM is above mean sea level (MSL) when the input satellite data is using a Toutin math model or when the input aerial data uses exterior orientation in MSL. With all other cases the output DEM is in ellipsoidal heights.

Elevation Unit

The unit for the elevation values in the source digital elevation model (DEM).

Available values are as follows:

Meter: Elevation values are represented in meters.
Feet: Elevations values are represented in International feet.
Automatic: Select this option when you want the module to automatically determine the elevation unit based on your input data.

Failed Pixel Value

The value attributed to pixels containing distortion or incorrect elevation values.

If no value is specified, a default value of -500 is applied.

Background Elevation

The pixel value representing background elevation (pixels where no elevation value is present) in the input digital elevation model (DEM).

If no value is specified for this parameter, the module checks for ELEVATION_BACKGROUND or NO_DATA_VALUE metadata tags, first at the channel level, and then at the file level. If a value is neither specified nor found in the metadata, the default value of -32768 is used for 16S and 32R data, 65535 for 16U, and 0 for 8U.

Look Directions

The look directions to use for extraction of the DEM.

Available options are:

Forward, Backward
Nadir, Backward
Nadir, Forward
Tri-stereo: Creates two intermediate epipolar digital surface models (DSM), one from the nadir-and-forward pair and the other from the nadir-and-backward pair. The two epipolar DSMs are then merged into a single epipolar DSM. This method produces DSMs with fewer occlusions and failed areas; however, computation time is increased.

Bit Depth

The bit depth of the images of the selected look directions. Only images of a matching bit depth are used to create the DSM and DTM.

You can select from:

Automatic: selects the bit depth of the first image.
8-bit: only 8-bit images are used to create the DSM and DTM.
16-bit: only 16-bit images are used to create the DSM and DTM.

Cost Function

Available when Semi-global Matching is selected for Extraction Method, the cost function to use for SGM.

You can select from the following:

Mutual Information: Provides more precise detail, but may introduce cross-hatching, terracing, or both in areas of uniform contrast.
Normalized Cross-Correlation: Provides less detail, but also less affected by areas of poor data quality.

Penalties

Available when Semi-global Matching is selected for Extraction Method, the penalty value based on that selected for Cost Function.

You can enter the value of the penalty as follows:

When Mutual Information is selected for Cost Function, applies a default of 20, 20000; however, you can enter greater or lesser values, as necessary, to increase or decrease quality.
When Normalized Cross-Correlation is selected for Cost Function, applies a default of 7, 7000; however, you can enter greater or lesser values, as necessary, to increase or decrease quality.

Segment Size

Available when Semi-global Matching is selected for Extraction Method, the threshold at which to eliminate segments and interpolate values of the digital elevation model (DEM) from the surrounding data. A segment is a small, isolated group of matching pixels.

Typically, values ranging from 16 through 128 provide satisfactory results in most cases. The default value is 64. A value of zero (0) switches off the operation.

Semi-global Filter

The level of SGM filtering to apply to the output DSM.

You can select from the following:

None
Low
Medium
High

Filtering is applied in successive applications of noise, median, and smoothing filters.

Pattern Suppression

The level of pattern suppression to apply.

You can select from the following:

None: Apply no pattern suppression.
Low: Apply minimal pattern suppression.
This option typically removes most smaller blunders without affecting other nonrelated features.
Medium: Apply moderate pattern suppression.
This option typically removes most blunders without affecting other nonrelated features.
High: Apply maximum pattern suppression.
This option typically removes almost all blunders and likely affects other nonrelated features. It can be effective when the required output is a digital terrain model (DTM) rather than a DSM.

Pattern suppression helps to reduce or eliminate blunders in the output digital surface model (DSM) with imagery that contains repeating patterns, such as rows of crops in an agricultural field or tiles on building roofs.

The higher the level of suppression, the greater the likelihood that degradation of other features occurs, such as loss of high building tops or small trees. If such features are important, consider selecting Low or doing no pattern suppression whatsoever. You may also want to consider manually removing the blunders or using pattern suppression only on problem images.

Track Epipolar Lines

Available only when you select a semi-global filter, select this check box to automatically track errors in epipolar lines. Tracking may increase quality, but may also increase computing time.

NCC Extraction Interval

The extraction interval for the DSM.

You can specify a value ranging from 1 through 32. Typically, a value of 1 (full-resolution) or 2 (half-resolution) is used for high detail. You can use a higher value, such as 8, to generate a quick preview, which you can use to check quality before generating the higher-resolution DSM.

Clip Amount

The amount of data to clip from the epipolar digital elevation models (DEM) before merging and geocoding.

This parameter specifies the amount of the actual image data that is clipped, either as a number of pixels or as a percentage of the image size.

You can select between Pixels or Percent using the Clip Units parameter.

You can enter up to two values:

The first value defines the number of pixels or percentage in the left-right direction
The second value defines the number of lines or percentage in the up-down direction

For example:

If Clip Units is set to Pixels:

If a value of 5,10 is entered, five pixels are clipped from the left and right edges, while 10 pixels are clipped from the top and bottom edges.
If a single value is specified, clipping is applied to all edges of the image. For example, if the specified value is 5, five pixels are clipped from all four edges.

If Clip Units is set to Percent:

If a value of 5,10 is entered, five percent is clipped from the left and right edges, and 10 percent from the top and bottom edges.
If a single value is specified, clipping is applied to all edges of the image. For example, if the specified value is 5, five percent is clipped from all four edges.

The default is blank, which means no clipping occurs. The maximum percentage value is 49 percent.

Clip Units

The unit to use for the value of the Clip Amount parameter.

Available options are:

Percent: defines the amount of clipping in units of percentage, based on the full size of the image
Pixels: specifies the exact number of pixels to clip

When you specify a value for the Clip Amount parameter, this parameter is mandatory; otherwise, it is not required.

SGM Extraction Interval

The extraction interval for the DSM.

You can specify a value of 1, 2, 4, 8, 16, or 32. Typically, a value of 1 (full-resolution) or 2 (half-resolution) is used for high detail. You can use a higher value, such as 8, to generate a quick preview, which you can use to check quality before generating the higher-resolution DSM.

Create DTM from DSM

Allows you to select whether to convert the output digital surface model (DSM) to a bare-Earth digital terrain model (DTM).

A DSM can have elevation values that reflect the top of canopy or top of buildings. However, for many processes, such as orthorectification, it is necessary to have a DTM that reflects the height of the bare Earth.

If you need more control over how the output DSM is converted to a DTM, then leave this parameter unchecked and use the DEM Convert (DSM to DTM) module after this job has completed.

Output DTM Pixel Size

The size of a pixel in the output digital terrain model (DTM).

The size is a multiple of the input DSM pixel size. The DSM is resampled accordingly.

You can select from the following:

1 x DSM: Output pixel is that of the DSM pixel size multiplied by one.
2 x DSM: Output pixel is that of the DSM pixel size multiplied by two.
3 x DSM: Output pixel is that of the DSM pixel size multiplied by three.
4 x DSM: Output pixel is that of the DSM pixel size multiplied by four.
5 x DSM: Output pixel is that of the DSM pixel size multiplied by five.

If you need more control over how the output DSM is converted to a DTM, then uncheck Create DTM from DSM and use the DEM Convert (DSM to DTM) module after this job has completed.

Filter Type

The type of filter to apply when converting to the digital terrain model (DTM).

For best results, select from the following the filter that best describes your data set:

Flat: Aggressively flattens protrusions in the terrain, such as buildings, hedges, and forests resulting in a very smooth DTM. This filter is best suited to flat areas with little-to-no natural-terrain protrusions.
Hilly: Flattens protrusions in the terrain while actively trying to preserve natural features. This filter can still remove buildings, but some artifacts may remain if they are detected as natural features. Hilly is best suited to scenes with elevations that vary naturally.
Hilly (Aggressive): Like Hilly, but with decreased gradients and a larger object size to more aggressively filter the DSM.
Flat (Low Detail/Satellite): Like Flat, but uses a different methodology to remove objects, because in a low-detail DSM, objects are not as sharp as in a high-detail DSM.
Hilly (Low Detail/Satellite): Like Hilly, but uses a different methodology to remove objects, because in a low-detail DSM, objects are not as sharp as in a high-detail DSM.
Custom: Provides you with complete control over the filtering to apply. That is, you can enter or select values for Object Size, Gradient Threshold, Terrain Type, Bump Filter, Pit Filter, Median Filter, and Clamp Filter, as necessary.
Note: Custom is available only with the DEM Convert (DSM to DTM) module.

If you need more control over how the output DSM is converted to a DTM, then uncheck Create DTM from DSM and use the DEM Convert (DSM to DTM) module after this job has completed.

Tip: You can touch up areas of difficulty in the DTM, such as removing any remaining artifacts, in the DEM Editing window of CATALYST Professional Focus.

Terrain Type

The types of terrain in the scenes.

Available options are:

Hilly: hilly terrain; this is the default value
Flat: gentle or flat terrain
Mountainous: mountainous terrain

Create DEM Mosaic

With this check box selected, each extracted DSM pair is mosaicked into one or more DSMs. With check box cleared, a DSM file is created for each extracted DSM pair.

DEM-Mosaic Method

Select the method to use to create the DEM mosaic.

The available options are as follows:

Cutlines: Standard mosaicking with cutlines. The Cutlines mosaic method is best suited when the input images only overlap by a small amount.
Smart Merge: Advanced mosaicking that merges overlapping DEM values and reduces occlusions. For each pixel in the output DEM, the Smart Merge mosaic method calculates a DEM value from all of the overlapping input geocoded DEMs. The Smart Merge mosaic method is best suited when there are several overlapping geocoded DEMs over the pixels.

Tile Specification

The mosaic tiling scheme to use for the output DEM.

Available schemes are:

Single Tile: Generates the output DEM as a single tile.
Dimensions: Creates DEM tiles of a specific size. When you select this option, you must specify values for the Tile Height and Tile Width parameters. When using this specification, the TileID values of the output tiles is generated using the convention <column_number>_<row_number>. For example, the upper-left tile always has a TileID of "1_1", the one immediately below is "1_2", and so on.

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:

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.

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:

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.

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.

Clean Up Building Edges

With this check box selected, the filter straightens building edges in the DSM. When selected, you can use the default of 13 for Edge-Cleaning Filter Size, or select a new size.

While building edges are the intended target, the filter also affects trees and cliff edges. If the DSMs do not contain buildings, it is recommended that you clear the check box.

Edge-Cleaning Filter Size

The window size of the Clean Up Building Edges filter.

You can use the default of 13, or you can select a new size. Available sizes are odd integers ranging from 5 through 31. Larger sizes are well suited to buildings with long, straight edges, but may have an adverse affect on buildings with curved or complex edges. If the DSMs do not contain buildings, and you still want to use the filter, make sure the Clean Up Building Edges check box is selected, and then select a small-to-very-small window size.

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:

DEM Blend: Blend the digital elevation model (DEM). In combination with the DEM score channel, DEM Blend can, for example, replace occluded or failed values with acceptable ones from another overlapping DEM, when necessary. This method is well suited to DEM-extraction projects that have a lot of occluded features.
Note: With Cutline Method, DEM Blend is applicable only to jobs that have an Extraction Method parameter, and for which you select Semi-global Matching.
Minimum Squared Difference: Specifies the minimum-squared-difference method. This method is suitable for most mosaicking projects, and in most cases produces the cleanest cutlines. The algorithm determines a cutline in each overlapped area between two adjacent images, with minimum-squared differences of gray values at the same locations of the region in all image channels.
Minimum Difference: Specifies the minimum-difference method. This method is suitable for most mosaicking projects. The algorithm determines a cutline in each overlapped area between two adjacent images, with minimum differences of gray values at the same locations of the region
Minimum Relative Difference: Specifies the minimum-relative-difference method. This method is similar to Minimum Difference, but provides better output in cases where similar sections of data appear dissimilar in different images
Edge: Specifies the edge-feature method. This method provides better output in urban-area mosaicking or in images containing many linear features. The objective of the Edge method is to avoid placing cutlines across linear features.
Maximum Data: Specifies that cutlines is on the boundary of the real image pixels, meaning that NoData pixels is ignored when the image boundary is determined.
Import: Uses the specified polygons as cutlines exactly as they appear in the vector file.
File Extents: Specifies that the cutline is the extents of the input image(s) and does not exclude NoData pixels from the cutline generation process.

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:

vector_file is the name of an existing vector layer to use as a constraint polygon. Using a constraining vector layer is useful when at least some of the input images include features, such as clouds, that you want to exclude from the final mosaic.
field_name is the attribute field that contains the image source.
segment_number is the number of the vector segment that contains the constraint polygon.

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:

the value of its file level metadata tag: SourceID, or if that tag does not exist, then
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:

Automatic: Determine whether constraints are required and, if so, applies one for each input image.
Classic: Create one constraint polygon for each input image using PCI traditional algorithm that was developed for aerial images that are approximately square and contain a lot of overlap. You can adjust the option by specifying a value for the Thiessen Factor. If you do not specify a value, the default value of 50 is applied.
Strips: Create one constraint polygon for each input image using PCI algorithm that was developed for projects that have a clear pattern of strips, such as often seen with ADS data. Images must be of similar size and align in at least one direction from, for instance, aerial flight lines or satellite swaths. Cutline-constraining polygons is generated for each image based on where it and its neighbors have actual data. This method first tries to group the images in rows or columns, and chooses the strips with the most consistent distance between images. It then removes the overlap between images in each strip using, at most, two neighboring images. Finally overlap is remove between the different strips leaving a constraining polygon. The extents of the polygons can be manipulated by specifying a value for the overlap Factor. If you do not specify a value, the default value of 20 is applied.
No: Does not apply constraint polygons.

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.

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.

DEM Extraction ADS module

Description

Parameters

Parameter descriptions

Details