GEOCODEDEM

Name	Type	Caption	Length	Value range
MFILE*	str	Input file name, directory, or text file	1 -
DBEC	List[int]	Input epipolar DEM channel	0 - 1
DBSCORE	List[int]	Input correlation score channel	0 - 1
DBIW	List[int]	Raster input window	0 - 4	Xoffset, Yoffset, Xsize, Ysize
FAILVALU	List[float]	DEM extraction failure value	0 - 1	Default: -100
BACKELEV	List[float]	Background value	0 - 1
DEMEDIT	str	Edit DEM	0 - 3	YES \| NO Default: YES
DEMCLIP	str	DEM Clip	0 - 16
FILO*	str	Output geocoded DEM file	1 -
ELEVREF	str	Vertical reference for elevation values	0 -	MSL \| ELLIPS
ELEVUNIT	str	Elevation value units	0 - 7	METER \| FEET \| US_FEET Default: METER
MAPUNITS	str	Output projection units	0 -	Default: None
UPLEFT	List[float]	Output image upper-left coordinate	0 - 2
LORIGHT	List[float]	Output image lower-right coordinate	0 - 2
PXSZOUT	List[float]	Output pixel size	0 - 2
MERGEOPT	str	DEM merge option	0 - 7	LAST \| AVERAGE \| SCORE \| BLEND Default: BLEND
MEMSIZE	List[int]	Working memory size	0 - 1	Default: 2000

Parameter descriptions

MFILE

Specifies the name of a folder, image file, or text file that contains the input epipolar or interferometric SAR (InSAR) DEM images to be processed. Wildcards (*) can be used.

MFILE can be set using any of the following options:

a specific data file name or directory path and file name; for example, "irvine.pix" or "c:\data\irvine.pix"
a specific file name pattern or all of the files in a folder; for example, "c:\data\*.pix" or "c:\data"
an existing text file that contains references to multiple files with, optionally, different parameter settings on a per file basis; for example, "c:\list.txt"

If the text file option is used, the following general rules apply:

Specify a .txt extension for the file containing multiple files and different parameter values.
List each set of parameters on its own line in the given order.
Specify string parameters within quotation marks.
Do not specify numeric parameters within quotation marks.
A quotation mark preceded by a backslash is used as part of the string. For example, 'ab\"c' is used as: ab"c.
Use an exclamation mark (!) before writing a comment in the text file.
Use semi-colons to delimit the parameters.
Leave the position between the semi-colons empty (";;") if you do not want to specify a value. Alternatively, if there are no remaining parameters to be specified on the end of a line, you may leave it blank.
Parameters in a text file may or may not be specified in the function:
- If a parameter is specified in the function and in the text file, the value provided in the text file is used.
- If a parameter is not specified in the text file, the parameter can be set in the function.

DBEC

Optionally specifies the input channel that contains the digital elevation model (DEM) to be extracted.

If this parameter is not specified, the function automatically searches the image, DEM, and, optionally, the correlation score (DBSCORE) channels from the input file. By default, the function will geocode the second channel in the input file.

DBSCORE

Specifies the channel that contains the correlation score. It is not used for the interferometric SAR DEMs.

DBIW

Specifies the raster window, in pixel and line coordinates, that is read from the input epipolar images. If this parameter is not specified, the entire layer is used by default.

Xoffset, Yoffset define the upper-left starting pixel coordinates of the window. Xsize is the number of pixels that define the window width. Ysize is the number of lines that define the window height.

If UPLEFT (Upper Left Coordinate) and LORIGHT (Lower Right Coordinate) are specified, this parameter is ignored.

FAILVALU

Specifies the value given to pixels for which the generation of elevation values failed. This value should be outside the range of valid elevation values. The failure value identifies the areas that can be interpolated and filled.

BACKELEV

Optionally specifies the background elevation value of the input and output DEM.

When the empty DEM file is first created, the function fills the entire DEM channel with the specified background elevation value. In the final DEM file, this value indicates areas that have no stereo images from which to extract elevation values.

Select a value that is different from the Elevation Failure Value (FAILVALU) and that is not a valid extracted elevation value for the area. For example, setting this parameter to 0 in a coastal area is a poor choice because a valid extracted elevation can match this value. If the FAILVALU and the NO_DATA_VALUE/BACKELEV value are the same then the algorithm will exit with an error.

If this parameter is not specified, the function checks for ELEVATION_BACKGROUND or NO_DATA_VALUE metadata tags, first at the channel level, then at the file level. If this value is not specified or found in the metadata, the function uses the default value of -32768.

If this parameter is specified and the NO_DATA_VALUE metadata tag is found in the input file then the algorithm will exit with an error. Overridding the NO_DATA_VALUE with this parameter can cause errors that are hard to diagnose. To fix the error do one of the following:

Modify the NO_DATA_VALUE value in the input file. If the NO_DATA_VALUE is wrong then choose this option.
Leave the BACKELEV parameter blank. If the NO_DATA_VALUE is correct then choose this option.
Set the BACKELEV to the same value as the NO_DATA_VALUE. This is an alternative to solution 2.

DEMEDIT

Specifies whether to automatically edit the DEM.

Supported options are:

YES (selected): small failed areas (holes) are interpolated. The interpolation process is based on an algorithm named Distance Transform. This is the default value.
NO (cleared): the DEM is not modified and the cells for which the elevation value generation fails are assigned the value specified in FAILVALU (Elevation Failure Value).

DEMCLIP

Specifies the amount of data to be clipped from the epipolar DEMs before merging and geocoding them. This functionality is possible only when FILEDEM is specified..

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

Two values can be entered:

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

For example, if a value of 5,10 is entered, five pixels are clipped from the left and right edges, while ten pixels are clipped from the top and bottom edges.

If a single value is specified and the value is positive, 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.

To clip based on a percentage of the image size, enter the % symbol after the value: for example, if a value of 5%,7% is entered, five percent is clipped from the left and right edges and seven percent from the top and bottom edges.

In some cases it is better to clip the output geocoded image based on the height computed from DEM world. This is because the extracted DEM may contain large elevation errors due to noise (such as water). If a negative %value is entered such as -10%, the geocoded extent would not exceed the extent computed using DEM world plus 10% on each side.

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

FILO

Specifies the name of the generated geocoded digital elevation model (DEM) file.

ELEVREF

The vertical reference for the elevation values in the generated geocoded DEM. If not specified, the value will be read from the epipolar DEM and the math model.

Acceptable values are as follows:

MSL: Elevations are referenced to mean sea level (MSL).
ELLIPS: Elevations are referenced to the ellipsoid. The coordinate system of the DEM georeferencing is used 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.

ELEVUNIT

The units of the elevation values that are stored as pixel values in the generated geocoded DEM.

Acceptable values are as follows:

METER (default value)
FEET
US_FEET

If you specify the elevation values as FEET, the conversion factor to meters is 0.3048 (corresponding to International Feet); if you specify US_FEET, the conversion factor is 1200/3937 (corresponding to U.S. Survey Feet).

If you do not specify a value for this parameter, the value of the ELEVATION_UNITS metadata tag of the DEM channel specified by DBEC is used. If the tag does not exist in the DEM, the default value is used.

MAPUNITS

Specifies the projection string for the output DEM. If not specified, the map units are determined automatically.

The standard definitions are as follows:

UTM: Universal Transverse Mercator
SPCS: State Plane Coordinate System
LONG/LAT: longitude and latitude
METER: image along-row and along-column meters
FEET: image along-row and along-column feet

If METER or FEET is specified, the math model and DEM must be METER or FEET.

If a regular, Earth-referenced projection is specified, the math model and DEM must also use a regular projection (not necessarily the same one); METER and FEET are not allowed.

The label of a user-defined projection may also be specified, if the projection exists in the userproj.txt file. Otherwise the projection parameter information must be provided as a string separated by the vetical bar ('|'). The projection parameter string defines 18 parameters delimited by spaces, including Dearth, RefLong, RefLat, StdParallel1, StdParallel2, FalseEasting, FalseNorthing, Scale, Height, Long1, Lat1, Long2, Lat2, Azimuth, LandsatNum, LandsatPath and UnitsCode. For instance, the projection named 'France93' may be specified as:

LCC D350 | 0 0 3.0 46.5 44.0 49.0 700000 6600000 0 0 0 0 0 0 0 0 0 -1

This parameter can specify 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).

The Earth model can be specified for LONG/LAT (and other units except METER or FEET), as follows:

LONG/LAT [Ennn]

This parameter can specify the SPCS zone number and Earth model as follows:

SPCS [mmmm] [Ennn]

where [mmmm] is is the four-digit zone number.

If the Earth model is not specified, it is assumed to be E000 (Clarke 1866).

If MAPUNITS is not specified, the logic for determining a default ortho coordinate system is as follows:

If the source raster has a coordinate reference system (CRS) that is projectable (not PIXEL, METER or FEET), it will be used for the output ortho.
Otherwise, the CRS from the MMSEG math model is analyzed. If the MMSEG math model is METER or FEET, a 2-D coordinate system of type METER or FEET will be chosen to match.
If the MMSEG math model is based on a projected coordinate system, the same projected coordinate system is chosen.
If the MMSEG math model is based on a geographic longitude/latitude coordinate system, a default projection based on the WGS84 datum will be selected, depending on the image position. If the image falls between 84 degrees North and 80 degrees South, a UTM projection with the appropriate zone number will be used. If the image falls in the polar regions, a Universal Polar Stereographic projection will be used.

UPLEFT

Optionally specifies the upper-left ground X and Y coordinates, in map units, for the output geocoded DEMs.

If this parameter is not specified, GEOCODEDEM calculates and uses the upper-left corner coordinate from the input DEM file.

LORIGHT

Optionally specifies the lower-right ground X and Y coordinate, in map units, for the output geocoded DEMs.

If this parameter is not specified, GEOCODEDEM calculates and uses the lower-right corner coordinate from the input DEM file.

PXSZOUT

Optionally specifies the resolution of the generated pixels. If this parameter is not specified, the resolution is automatically determined from the input epipolar DEM files.

The units of this parameter must be the same as the units of the math models used to generate the epipolar DEM. For images using the RPC math model, this is generally LONG/LAT; for most other math models, it is a projected coordinate system in meters or feet.

If multiple epipolar DEMs are provided, the first DEM processed is used to determine the units and resolution.

MERGEOPT

Optionally specifies the DEM merging option to use when multiple epipolar DEMs are geocoded and added to the output DEM file.

When a new geocoded DEM is added to the file and it overlaps an existing geocoded DEM, you must specify the method by which to determine the pixel value to use.

Valid methods are:

LAST (Use last value): uses the last value to replace the pixel values in the overlapped area in the existing geocoded DEM by the pixel values of the geocoded DEM that is added to the file.
AVERAGE: replaces the pixel values in the overlapped area by the average pixel values between the existing geocoded DEM and the one that is added to the file.
SCORE (Highest score): uses the highest score to replace the pixel values in the overlapped area by the pixel value with the highest correlation score between the existing geocoded DEM and the one that is added to the file.

This option is used only if you create the score channel (SCORCHAN) during the epipolar DEM creation.
BLEND (Blending): uses the mosaicking method to mosaic the DEMs together with blending between DEMs. This is the default value.

Note: This option is used only if you create the score channel (SCORCHAN) during the epipolar DEM creation.

MEMSIZE

The amount, in megabytes (MB), of internal memory to allocate to processing.

Environments	PYTHON :: EASI :: MODELER
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GEOCODEDEM

Geocode DEM from epipolar DEM

Description

Parameters

Parameter descriptions

Return Value

Details

Example

References