Imagery - Appendices

These appendices include useful background information for this workflow not included in previous topics.

XML formatted text representing an *.aux.xml file for georeferencing nonrectified images

The text below provides an example of the content required to perform a projective transformation for georeferencing a nonrectified image. This text could be used as a template and saved as <filename>.aux.xml, with unique coordinates required for each image file, presumably to be edited and saved through a batch process you will have to develop.

The coordinates are stored in the tags labeled <SourceGCPs> and <TargetGCPs>. The coordinate pairs represent the upper-left, upper-right, lower-left, and lower-right corners of the image file, respectively (in image space or simple pixel coordinates)—in this case, for an image 1,453 columns (x) by 1,921 rows (y) in the <SourceGCPs>, followed by corresponding longitude (x) and latitude (y) values in GCS_WGS_1984 coordinates.

Note:

Some attributes listed in the <Metadata> fields may need to be modified based on your input images.

An example of .aux.xml that contains metadata fields and attributes to perform a projective transformation for georeferencing a nonrectified image.

<PAMDataset>
  <Metadata domain="IMAGE_STRUCTURE">
    <MDI key="SOURCE_COLOR_SPACE">YCbCr</MDI>
    <MDI key="INTERLEAVE">PIXEL</MDI>
    <MDI key="COMPRESSION">JPEG</MDI>
  </Metadata>
  <Metadata domain="Esri">
    <MDI key="PyramidResamplingType">NEAREST</MDI>
  </Metadata>
  <Metadata domain="xml:ESRI" format="xml">
    <GeodataXform xsi:type="typens:ProjectiveXform" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:typens="http://www.esri.com/schemas/ArcGIS/10.1">
      <SpatialReference xsi:type="typens:GeographicCoordinateSystem">
<WKT>GEOGCS[&quot;GCS_WGS_1984&quot;,DATUM[&quot;D_WGS_1984&quot;,SPHEROID[&quot;WGS_1984&quot;,6378137.0,298.257223563]],PRIMEM[&quot;Greenwich&quot;,0.0],UNIT[&quot;Degree&quot;,0.0174532925199433],AUTHORITY[&quot;EPSG&quot;,4326]]</WKT>
        <XOrigin>-400</XOrigin>
        <YOrigin>-400</YOrigin>
        <XYScale>11258999068426.24</XYScale>
        <ZOrigin>-100000</ZOrigin>
        <ZScale>10000</ZScale>
        <MOrigin>-100000</MOrigin>
        <MScale>10000</MScale>
        <XYTolerance>8.983152841195215e-009</XYTolerance>
        <ZTolerance>0.001</ZTolerance>
        <MTolerance>0.001</MTolerance>
        <HighPrecision>true</HighPrecision>
        <LeftLongitude>-180</LeftLongitude>
        <WKID>4326</WKID>
        <LatestWKID>4326</LatestWKID>
      </SpatialReference>
      <SourceGCPs xsi:type="typens:ArrayOfDouble">
        <Double>0.0</Double>
        <Double>0.0</Double>
        <Double>1452.0</Double>
        <Double>0.0</Double>
        <Double>0.0</Double>
        <Double>-1920.0</Double>
        <Double>1452.0</Double>
        <Double>-1920.0</Double>
      </SourceGCPs>
      <TargetGCPs xsi:type="typens:ArrayOfDouble">
        <Double>-122.62817879281903</Double>
        <Double>45.636684801338085</Double>
        <Double>-122.61170102535365</Double>
        <Double>45.636407197554092</Double>
        <Double>-122.62919006374651</Double>
        <Double>45.614635129350745</Double>
        <Double>-122.61134410620278</Double>
        <Double>45.614278210199871</Double>
      </TargetGCPs>
    </GeodataXform>
  </Metadata>
</PAMDataset>

10/28/2013