Geodata transformation object

Overview

This topic discusses the JSON representation of geodata transformation objects. The image service's Add and Update operations support a geodataTransforms parameter. This parameter is an array of geodataTransform objects.

A geodataTransform object has the following JSON syntax:

Syntax
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{
  "geodataTransform": "<geodataTransformName>",
  "geodataTransformArguments": {<geodataTransformArguments>}
}

The structure of the geodataTransformArguments object varies based on the geodataTransform type. There are three types of geodataTransform objects, which are listed below:

Polynomial transformation
Projective transformation
Identity transformation

Polynomial transformation

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{
  "geodataTransform": "Polynomial",
  "geodataTransformArguments": {
    "sourcePoints": [<sourcePoint1>, <sourcePoint2>, <sourcePoint3> ...], //array of points
    "targetPoints": [<targetPoint1>, <targetPoint2>, <targetPoint3> ...], //array of points
    "coeffx": [<coeffx11>, <coeffx12>], //array of doubles
    "coeffy": [<coeffy11>, <coeffy12>], //array of doubles
    "inverseCoeffx": [<inverseCoeffx11>, <inverseCoeffx12>], //array of doubles
    "inverseCoeffy": [<inverseCoeffy11>, <inverseCoeffy12>], //array of doubles
    "spatialReference": {<spatialReference1>},
    "polynomialOrder": <polynomialOrder1> //integer: 1, 2, or 3. First order requires at least 3 pairs of control points; second order requires at least 6 pairs of control points; third order requires at least 10 pairs of control points; use more control points to get better fit (smaller RMS)
  }
}

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{
  "geodataTransform": "Polynomial",
  "geodataTransformArguments": {
    "sourcePoints": [{"x":0.0, "y":0.0}, {"x":0.0, "y":200.0}, {"x":200.0, "y":0}],
    "targetPoints": [{"x":100.0, "y":100.0}, {"x":100.0, "y":300.0}, {"x":300.0, "y":100.0}],
    "polynomialOrder": 1,
    "spatialReference": {"wkid" : 54004}
  }
}

Projective transformation

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{
  "geodataTransform": "Projective",
  "geodataTransformArguments": {
    "sourcePoints": [<sourcePoint1>, <sourcePoint2>, <sourcePoint3> ...], //array of points
    "targetPoints": [<targetPoint1>, <targetPoint2>, <targetPoint3> ...], //array of points
    "coeffx": [<coeffx11>, <coeffx12>...], //array of doubles
    "coeffy": [<coeffy11>, <coeffy12>...], //array of doubles
    "inverseCoeffx": [<inverseCoeffx11>, <inverseCoeffx12>], //array of doubles
    "inverseCoeffy": [<inverseCoeffy11>, <inverseCoeffy12>], //array of doubles
    "spatialReference": {<spatialReference1>}
  }
}

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{
  "geodataTransform": "Projective",
  "geodataTransformArguments": {
    "sourcePoints": [ {"x":551.18, "y":817.09}, {"x":653.84, "y":714.43}, {"x":819.49, "y":712.10}, {"x":895.71, "y":789.87} ],
    "targetPoints": [ {"x":596.29, "y":878.53}, {"x":655.39, "y":815.54}, {"x":733.94, "y":806.21}, {"x":765.05, "y":850.54} ],
    "spatialReference": {"wkid" : 54004}
  }
}

Identity transformation

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{
  "geodataTransform": "Identity",
  "geodataTransformArguments": {
    "spatialReference": {<spatialReference1>}
  }
}

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{
  "geodataTransform": "Identity",
  "geodataTransformArguments": {
    "spatialReference": {"wkid": 54004}
  }
}