TORTHO

Name	Type	Length	Value range
Input: Input raster channel(s)	Raster port	0 - 1024
InputMM: Input math-model segment	BIN port port	0 - 1
Raster input window	Integer	0 - 4	XOff, YOff, XSize, YSize
RADIODIF	String	0 -	Default: LOW
Output Background	Float	0 - 1	Default: 0
Automatic Edge Clipping	Integer	0 - 1	0 - 49 Default: 0
Output Projection	String	0 - 1
Horizontal Pixel Size *	String	1 - 1
BYPXSZ	String	0 - 1
Tile Positioning Transformation	String	0 -
InputDEM: Input elevation channel	DEM port	0 - 1
Background Elevation Value	Float	0 - 1
Elevation Reference	String	0 -	MSL \| ELLIPS \| MATHMODEL
Elevation Units	String	0 - 1	METER \| FEET \| US_FEET
Elevation Offset and Scale	Float	0 - 2
Building Model Error	Integer	0 - 1	0 - Default: 1
InputDBM: Input-vector layer	DBM port	0 - 1
DBM Elevation Reference	String	0 -	MSL \| ELLIPS \| MATHMODEL Default: MSL
DBM Elevation Units	String	0 - 1	METER \| FEET \| US_FEET Default: METER
DBM Elevation Offset and Scale	Float	0 - 2	Default: 0.0,1.0
Resample Mode	String	0 -	Default: CUBIC
ALGO	String	0 -	See Parameter Details. Default: OCCLUDE

Parameter descriptions

Input: Input raster channel(s)

The channel or channels to process in the input file.

Each channel must contain the same data type. If no value is specified for this parameter, all of the channels in the source file will be processed.

InputMM: Input math-model segment

The math-model segment of the input raw image to use in the orthorectification process. All math-model types are supported.

If this parameter is not specified, the last model segment of the input file is used.

This parameter can be overridden by a corresponding value in the MFILE text file.

Raster input window

The raster window (Xoffset, Yoffset, Xsize, Ysize) of data to read from the input channels.

If no value is specified for this parameter, the entire image is processed. XOff, YOff 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.

Note: This parameter is particularly useful when orthorectifying scanned-film airphotos, as it can be used to exclude the registration marks and ancillary data printed along the edge of the image.

RADIODIF

The allowable extent of radiometric difference between a candidate image and the current image for it to be considered for occlusion recovery.

The following values are supported:

ANY
LOW
MODERATE
HIGH

This parameter can be overridden by an entry in the MFILE.

Output Background

The background (NoData) value to use for ortho pixels that are not populated. Each channel is set to the same background value. The background value provided is truncated to the range allowed by the source image data type.

Automatic Edge Clipping

The percentage of the image that is clipped from the edges during orthorectification. Clipping is applied to each edge of the image; for example, if the value specified is 5, five percent is clipped from the left-most edge and five percent from the right-most edge). The maximum value is 49 (percent).

Edge clipping is performed after the ortho image extents (ULX, ULY, LRX, LRY) are determined, but before the tile-positioning transformation (TIPOSTRN) is applied.

Note: This parameter is particularly useful for images in a north-south or east-west orientation, as it can be used to clip the undulating boundary that arises due to relief displacement.

Output Projection

The projection string for the output ortho image. If no value is specified for this parameter, 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 digital elevation model (DEM) must also use a regular projection (not necessarily the same one); neither METER nor FEET are allowed.

The label of a user-defined projection can also be specified if it exists in the file userproj.txt. Otherwise, the projection-parameter information must be provided as a string separated by a vertical 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 example, the projection "France93" can 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 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 (neither PIXEL, METER, nor 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 two-dimensional (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 will be 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.

Horizontal Pixel Size

The horizontal pixel size of the output image.

The output-pixel size is expressed in the units of the ortho coordinate system.

BYPXSZ

The vertical pixel size of the output image.

The output-pixel size is expressed in the units of the ortho coordinate system.

If no value is specified for this parameter, the value specified for the horizontal pixel size (BXPXSZ) is used.

Tile Positioning Transformation

An upper-left corner-coordinate adjustment for the orthorectified image.

This parameter allows you to generate ortho images that occur in a specific raster grid. You specify it by providing a keyword and either two or four values.

The keyword indicates the relative positioning of the values:

CORNER: values are relative to the upper-left corner of the first pixel in the output file
CENTER: values are relative to the center of the first pixel in the output file

After the keyword is specified, the values are:

Stride_X
Stride_Y
Ref_X
Ref_Y

These values define the position of the corner or center relative to the specified 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, Ref_Y default to 0.

Stride_X must double an integer multiplier of the horizontal pixel size, and Stride_Y must double an interger multiplier of the vertical pixel size.

For example:

TIPOSTRN="CORNER, 20, 20, 432345.000, 5438882.000"

In the preceding example, the upper-left corner of the upper-left pixel of the image will be an even 20-unit multiple from the reference point (432345.000, 5438882.000). Depending on the distance of the tile from that point, its upper-left x-coordinate can be 432345.000, 432365.000, or any other multiple, but will never be 432346.000 nor 432355.000.

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

This parameter is optional.

InputDEM: Input elevation channel

Specifies the channel number for the input digital elevation model (DEM) elevation channel to be processed.

If there is only one channel, it is used as the DEM channel.
If there are two or more channels, the correct one is selected according to the following criteria, in order of precedence:
1. The first channel with any one of the DEM-related metadata tags: "ELEVATION_DATUM", "ELEVATION_UNITS", "ELEVATION_FACTOR", "ELEVATION_OFFSET", "ELEVATION_SCALE", "DEM_Z_ACCURACY", "ElevationModel".
2. The first channel with a description containing any of the strings: "DEM", "DSM", "DTM", "ELEVATION".
3. The first 32-bit-real (32R) channel.
4. The first 16-bit-integer (16U or 16S) channel.
5. If no channels match the preceding criteria, the first channel in the file is selected.

Background Elevation Value

The background elevation (NoData) value in the input elevation channel.

Output ortho pixels with this value are set to the value of OUTBGD (Output Background), as it is impossible to interpolate a height for these pixels.

If no value is specified for this parameter, the function checks for ELEVATION_BACKGROUND or NO_DATA_VALUE metadata tags, first at the channel level, and then at the file level. If this value is not specified or found in the metadata, the function uses the default value of -32768.

This parameter is optional.

Elevation Reference

The vertical reference for the elevation values contained in the source digital elevation model (DEM), or for the constant value of ELFACTOR, if it is used.

Acceptable values are:

MSL: elevations are referenced to Mean Sea Level. If no value is specified, MSL is applied by default. The EGM2008 geoid model will be used to convert these to ellipsoidal heights.
ELLIPS: elevations are referenced to the ellipsoid. The coordinate system of the DEM-raster file is examined to determine which ellipsoid and datum are to be used; for instance, 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 will be converted automatically to the math-model-coordinate system before use.
MATHMODEL: heights are in the same height datum as the math model specified in for the MMSEG parameter. This option is used to disable explicitly any height translation when you know that the DEM and math model use the same height datum.

Elevation Units

The units of the elevation values that are stored as pixel values in the input digital elevation model (DEM), as specified either by FILEDEM or by the first entry in ELFACTOR.

Acceptable values are:

METER (default)
FEET
US_FEET

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

Elevation Offset and Scale

If an input digital elevation model (DEM) is specified and will be used in the orthorectification (see FILEDEM), the value of this parameter is used to shift and scale the DEM pixel values to values in the units indicated by the value of ELEVUNIT (Elevation Unit).

Using this parameter, two values are specified: the first defines the offset, and the second, optionally, specifies the scale.

The conversion formula is as follows:

elevation_value = scale * (DEM_pixel_value + offset)

If no value is specified for ELFACTOR, an offset of 0.0 is applied by default, and the scale default is 1.0.

Building Model Error

The accuracy of the building models in units of ortho pixels.

This parameter is used to grow the occluded regions before they are filled in with data from neighboring images. This allows the algorithm to compensate for small inaccuracies in the elevation data set.

InputDBM: Input-vector layer

The segment number for the input digital building model (DBM) vector layer to be processed. The specified vector layer must contain three-dimensional (3-D) triangles that represent building rooftops.

DBM Elevation Reference

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

Acceptable values are:

MSL: elevations are referenced to Mean Sea Level (MSL). If no value is specified for ELEVREF, MSL is the default value. The EGM2008 geoid model will be used to convert these to ellipsoidal heights.
ELLIPS: elevations are referenced to the ellipsoid. The coordinate system of the digital elevation model (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. If the DEM and math model are based on different coordinate systems, the heights will be converted automatically to the math model coordinate system before use.
MATHMODEL: heights are in the same height datum as the math model specified for the MMSEG parameter. This option is used to disable explicitly any height translation when you know that the DEM and math model use the same height datum.

DBM Elevation Units

The units of the elevation values stored as vertex z-coordinates in the input digital building model (DBM), as specified by the value of FILEDBM.

Acceptable values are:

METER (default)
FEET
US_FEET

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

DBM Elevation Offset and Scale

If an input digital building model (DBM) is specified and will be used in the orthorectification (see FILEDBM), the value of this parameter is used to shift and scale the vertex z-coordinates to values in the units indicated by the value of DBMELEVUNIT (Elevation Unit).

Using this parameter, two values are specified: the first defines the offset while the second, optionally, specifies the scale.

The conversion formula is as follows:

elevation_value = scale * (Vertex_Z_value + offset)

If no value is specified for ELFACTOR, the offset default is 0.0 and the scale default is 1.0.

Resample Mode

The resampling method to use in the orthorectifying process.

The following methods are supported:

NEAR: nearest neighbor
BILIN: bilinear interpolation
CUBIC: cubic convolution (default)
SINC8,SHAPINGWINDOW=[sw],BETA=[beta]: 8 point sin(x)/x
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 the SHAPINGWINDOW is KAISER. It 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.
SINC16,SHAPINGWINDOW=[sw],BETA=[beta]: 16 point sin(x)/x
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 the SHAPINGWINDOW is KAISER. It 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.
CPLXSAR,NUMCOLS=[nc],NUMROWS=[nr],FC=[fc]: Complex SAR resampler. Requires complex data.
where:
- NUMCOLS is the width of the resampling window (odd number from 1 to 31)
- NUMROWS is the height of the resampling window (odd number from 1 to 31)
- FC is the normalized central frequency of the SAR image (value from -0.5 to 0.5). FC is optional; if unspecified, a default value of 0.0 is used.
AVERAGE,NUMCOLS=[nc],NUMROWS=[nr]: "Average" resampler for generating downsampled products
MEDIAN,NUMCOLS=[nc],NUMROWS=[nr]: "Median" resampler for generating downsampled products. NUMCOLS and NUMROWS can be any value from 1 to 11.
LAGRANGE4: four-point Lagrange interpolation
LAGRANGE8: eight-point Lagrange interpolation

For 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 directs the resampler to use the nearest-neighbor method, while BGD indicates that the output pixel will be set to the background value. By default, NN is used as the value of FILL.

ALGO

Specifies the algorithm. The following values are valid:

OCCLUDE: This algorithm is often referred as true orthorectification. When the line-of-sight connecting the ground surface and the camera is obscured, it is not visible on the imagery. Occlusion algorithm is to identify and locate such obscured objects in ground space, and to fill them if they are visible on any overlapping images.
- HOLESIZE: Specify the diameter of remaining holes to be interpolated in unit of pixels. If not specified, default to 4 pixels. If specifying -1, the hole size is unlimited.
STRETCH: When the line-of-sight has a large incidence angle with respect to the ground surface, the object will appear at a low resolution in the imagery. Stretching algorithm is to identify low resolution areas, and replace them if they are imaged at a higher-resolution on any overlapping images. Two options can be specified.
- INDEX: Specify the index indicating stretched effect within a range [4, 14]. A smaller value indicates the more serious stretching. If not specified, it is default to 9.
- AREA: Specify the minimum number of pixels of a connected component that is considered a valid stretch. Any component having less number of pixels are considered as noise and thus are excluded. If not specified, it is default to 100.
- DEFRAG: Specify the size of a filtering window that is used to defrag stretched pixels for smoother seamlines. If not specified, it is default to 20.

Environments	PYTHON :: EASI :: MODELER
Batch Mode	Yes
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TORTHO

True orthorectification of imagery

Description

Parameters

Parameter descriptions

Details