Data Triangulation

ERDAS IMAGINE Help

HGD_Variant
16.5.1
HGD_Product
ERDAS IMAGINE
HGD_Portfolio_Suite
Producer

Category: Photogrammetry

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data_triangulation_default

data_triangulation_all

Description

Performs triangulation of RPC models using a polynomial-based refinement method based on the input control points. The output includes the adjusted model parameters, model transforms and triangulated points whose ground coordinates are defined in the Geographic (Lat/Lon) coordinate system using WGS 84 as the horizontal and vertical datum, degrees as the horizontal units, and meters as the vertical units.

This operator supports only those RPC models with the coordinate reference system defined in Geographic (Lat/Lon) using WGS 84 as the horizontal and vertical datum, degrees as the horizontal units, and meters as the vertical units.

For more information, see Single Frame Orthorectification/Block Triangulation.

Connections

ModelFilenameTemplateIn, ModelFilenameTemplateOut

Name of a template file used to define the directory and suffix of the output RPC model parameters. For any input raster that has a converged solution, a model parameter file is created in the template directory with a file name composed from the file name parts of the input raster and the template.

For example, if the template file name is c:\temp\rpc.txt and the input raster file is inputraster.tif, a model parameter file inputraster_rpc.txt is created in c:\temp\.

Each output parameters file uses an ASCII format based on the RPC00B format definition of RPC coefficients (see Table 8.22 in http://geotiff.maptools.org/STDI-0002_v2.1.pdf).

Output file names are recorded as RPCFilename in the ImageNameList of the ControlPointsOut.

TransformFilenameIn, TransformFilenameOut

Name of a template file used to define the directory and suffix of the output model transforms. For any input raster that has a converged solution, a model transform file is created in the template directory with a file name composed from the file name parts of the input raster and the template.

For example, if the template file name is c:\temp\transform.txt and the input raster file is inputraster.tif, a model transform file inputraster_transform.txt is created in c:\temp\.

Each output transform file contains a Dictionary object in JSON format that includes Georeferencing, Error and ErrorUnits. The Georeferencing uses the type of CoordinateOperation to store the geometric transformation information. The Error is the root mean square error measured in ErrorUnits.

Output file names are recorded as TransformFilename in the ImageNameList of the ControlPointsOut.

ControlPointsIn

A file containing a Dictionary object in JSON format that includes GroundPointList, ImageNameList and ImagePointList of IMAGINE.FeatureSubset.

GroundPointList lists point geometry with ground coordinates (X, Y, Z) and point properties with GroundID, Description, PointType, PointUsage, StandardDeviationX, StandardDeviationY, and StandardDeviationZ.

Ground coordinate X and Y are in degrees defined in the Geographic (Lat/Lon) coordinate system using WGS 84 as its horizontal datum. The ground coordinate Z is in meters defined in the WGS 84 vertical datum.

PointType has four values:

  • Full (all X, Y and Z coordinates defined)
  • Horizontal (X and Y coordinates defined)
  • Vertical (Z coordinate defined)
  • None (no ground coordinate defined)

PointUsage is either Control, Check, or Tie.

GroundID attribute and coordinates (X, Y, Z) are required. If the PointType and PointUsage are not provided, the PointType is Full and the PointUsage Control.

StandardDeviationX, StandardDeviationY, and StandardDeviationZ are in the same units as the ground coordinates (X, Y, Z). If the ground point geometry defines a coordinate reference system other than Geographic (Lat/Lon) using WGS 84 as the horizontal and vertical datum, degrees as the horizontal units, and meters as the vertical units, then the ground coordinates (X, Y, Z), StandardDeviationX, StandardDeviationY, and StandardDeviationZ are converted.

ImageNameList lists ImageID and ImageName. The names of Raster Filenames In and ImageName without path are compared to find the corresponding ImageID. If two or more images in Raster Filenames In have the same name, the comparison is done using the full-path names.

ImagePointList lists GroundID, ImageID, ImageX, and Image.

ControlPointsOut

A file containing a Dictionary object in JSON format that includes GroundPointList, ImageNameList and ImagePointList of IMAGINE.FeatureSubset.

GroundPointList lists point geometry with ground coordinates (X, Y, Z) and point properties with GroundID, Description, PointType, PointUsage, StandardDeviationX, StandardDeviationY, StandardDeviationZ, ResidualX, ResidualY, and ResidualZ.

Ground coordinate X and Y are in degrees defined in the Geographic (Lat/Lon) coordinate system using WGS 84 as its horizontal datum. The ground coordinate Z is in meters defined in the WGS 84 vertical datum.

PointType has four values:

  • Full (all X, Y and Z coordinates defined)
  • Horizontal (X and Y coordinates defined)
  • Vertical (Z coordinate defined)
  • None (no ground coordinate defined)

PointUsage is either Control, Check, or Tie.

StandardDeviationX, StandardDeviationY, StandardDeviationZ, ResidualX, ResidualY, and ResidualZ are in the same units as the ground coordinates (X, Y, Z).

ImageNameList lists ImageID, ImageName, TransformFilename and RPCFilename. The TransformFilename and RPCFilename are optional attributes, depending on the presence of Model Transform Filename Out and Model Parameters Filename Out. For each of these attributes, if the attribute is present, but the corresponding attribute value for a given ImageID is empty, this indicates that a converged solution was not reached for this input image and no corresponding result file was produced.

ImagePointList lists GroundID, ImageID, ImageX, ImageY, ResidualX, and ResidualY.

TriangulationParameters

A Dictionary object that includes one or more following items: PolynomialOrder, NumberOfIterations, GroundConvergenceValue, GroundControlValueType, StandardDeviationX, StandardDeviationY, and StandardDeviationZ.

PolynomialOrder has three possible values (-1, 0, 1):

  • -1 - no adjustment is applied to the RPC model and running triangulation will only calculate the ground positions for tie points and compute the residuals and standard deviations for tie points and check points.
  • 0 - one constant adjustable term for each dimension in image space.
  • 1 - the 1st order polynomial with three adjustable parameters for each dimension.

Assuming x = RPC_Function_X (X, Y, Z) and y = RPC_Function_Y (X, Y, Z) are current RPC models where (X, Y, Z) are the ground coordinates and (x, y) are the image coordinates, the 0th order means x' = a0 + x and y' = b0 + y where a0 and b0 are the adjustable parameters and (x', y') the adjusted image coordinates. For the 1st order the analogous equations are x' = a0 + a1*x + a2*y and y' = b0 + b1*x + b2*y where (a0, a1, a2) and (b0, b1, b2) are the adjustable parameters.

GroundConvergenceValue is the maximum convergence threshold in meters.

GroundControlValueType determines how the ground control point (GCP) coordinates are treated during the triangulation. Possible values:

  • Fixed - GCPs are considered fixed and no standard deviation is needed.
  • Same - apply the same standard deviation values (defined in StandardDeviationX, StandardDeviationY, StandardDeviationZ) to the X, Y, and Z coordinates.
  • Different - apply different standard deviation values to the X, Y, and Z coordinates.

In this case, the standard deviation values come from the ControlPointsIn. If not available from ControlPointsIn, the same StandardDeviationX, StandardDeviationY, and StandardDeviationZ are applied to all GCPs.

StandardDeviationX, StandardDeviationY, and StandardDeviationZ are in meters.

Name

Objects Supported

Description

Shown by Default

Required

Default Behavior or Behavior if not Required

RasterFilenames

List of File

List of raster file names that have associated RPC model information. Their RPC models may be embedded or associated with the raster files, or supplied in an optional model file name list (see ModelFilenames).

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SensorModelName

String

Text string for RPC sensor model name. To process images from several sensors use either the NITF RPC or DPPDB model and ensure that all images are in NITF format. If you do not use these two options, all images included in the process must be of the same sensor model type.

Valid sensor model names are:

  • IKONOS
  • NITF RPC
  • QuickBird RPC
  • ORBIMAGE RPC
  • CARTOSAT RPC
  • RESOURCESAT RPC
  • ALOS RPC
  • WorldView RPC
  • DPPDB
  • IND High Res RPC
  • GeoEye RPC
  • KOMPSAT RPC
  • DEIMOS RPC
  • RAPIDEYE RPC
  • PLEIADES RPC
  • SPOT6 RPC
  • SPOT7 RPC
  • TH-01 RPC
  • SkySat RPC
  • GOKTURK/RASAT RPC
  • ZY-3 RPC
  • KazEOSat-1 RPC

CARTOSAT RPC only works when the executable file importersnrsa.exe for importing ERS (CEOS) is present.

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ModelFilenames

List of File

List of the RPC model file names corresponding to the raster files specified in RasterFilenames. This list must have the same order as the RasterFilenames for these two lists to be associated correctly. This is optional if an RPC sensor model is automatically discoverable for each of the raster files.

ControlPointsIn

Dictionary

See ControlPointsIn section.

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TriangulationParameters

Dictionary

See TriangulationParameters section.

PolynomialOrder = 0

NumberOfIterations = 10

GroundConvergenceValue = 0.0001 meters

GroundControlValueType = Fixed

StandardDeviationX = 1 meter

StandardDeviationY = 1 meter

StandardDeviationZ = 1 meter

ModelFilenameTemplateIn

File

See ModelFilenameTemplateIn section.

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TransformFilenameIn

File

See TransformFilenameIn section above.

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ReportFilenameIn

File

Name for the text file that is created to summarize the results of the process.

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ControlPointsOut

Dictionary

See ControlPointsOut section.

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ModelFilenameTemplateOut

File

See ModelFilenameTemplateOut section.

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TransformFilenameOut

File

See TransformFilenameOut section.

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ReportFilenameOut

File

Name for the text file that is created to summarize the results of the process.

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Example Model

data_triangulation_model