[Gdal-dev] Problems with gdal_grid

[Tamas Szekeres]

2008/4/17, PikoBoZ <piklas at gmail.com>:

>  Is it simpler to interpolate from .shp or to use a .vrt / .csv couple ?
>  How can I specify to gdal_grid a data field to interpolate?

You'll have to use a vrt something like:

<OGRVRTDataSource>
    <OGRVRTLayer name="sample">
        <SrcDataSource>sample.csv</SrcDataSource>
	<GeometryType>wkbPoint25D</GeometryType>
	<GeometryField encoding="PointFromColumns" x="xfield" y="yfield"
z="myzvaluetointerpolate"/>
    </OGRVRTLayer>
</OGRVRTDataSource>


>  Is it possible to get a RGB GTiff from gdal_grid and to apply style (killing
>  nodata, Min/Max colors...)
>

If you can use the latest SVN trunk, you could possibly define a .vrt
and include a lookup table to map between grid values to the color
values. Here's an example:

<VRTDataset rasterXSize="500" rasterYSize="500">
  <VRTRasterBand dataType="Byte" band="1">
    <ColorInterp>Red</ColorInterp>
    <ComplexSource>
      <LUT>4567.12:0,123434.23:128,1234567.34:255</LUT>
      <SourceFilename>mygrid.tif</SourceFilename>
      <SourceBand>1</SourceBand>
    </ComplexSource>
  </VRTRasterBand>
  <VRTRasterBand dataType="Byte" band="2">
    <ColorInterp>Green</ColorInterp>
    <ComplexSource>
      <LUT>4567.12:0,123434.23:128,1234567.34:255</LUT>
      <SourceFilename>mygrid.tif</SourceFilename>
      <SourceBand>1</SourceBand>
    </ComplexSource>
  </VRTRasterBand>
  <VRTRasterBand dataType="Byte" band="3">
    <ColorInterp>Blue</ColorInterp>
    <ComplexSource>
      <LUT>4567.12:0,123434.23:128,1234567.34:255</LUT>
      <SourceFilename>mygrid.tif</SourceFilename>
      <SourceBand>1</SourceBand>
    </ComplexSource>
  </VRTRasterBand>
  <VRTRasterBand dataType="Byte" band="3">
    <ColorInterp>Alpha</ColorInterp>
    <ComplexSource>
      <LUT>4567.12:0,123434.23:128,1234567.34:255</LUT>
      <SourceFilename>mygrid.tif</SourceFilename>
      <SourceBand>1</SourceBand>
    </ComplexSource>
  </VRTRasterBand>
</VRTDataset>

for more information see:  http://www.gdal.org/gdal_vrttut.html


Best regards,

Tamas