[R-sig-Geo] Interrupted Goode Homolosine forest data

[Steve Pickering]

Hi, all,

I'm working with Global Forest Canopy Density data (specifications
here: http://edc2.usgs.gov/glcc/fao/data_specifications.php).

The data are in Interrupted Goode Homolosine projection.  I need to
use R to display them in unprojected lat lng format.

So far, I can display the projected version as follows:

First, create a test.vrt file with the following markup:

    <VRTDataset rasterXSize="36543" rasterYSize="15059">
    <VRTRasterBand dataType="Byte" band="1" subClass="VRTRawRasterBand">
        <SourceFilename
relativetoVRT="1">global_forest_density.img</SourceFilename>
        <ImageOffset>0</ImageOffset>
        <PixelOffset>1</PixelOffset>
        <LineOffset>36543</LineOffset>
        <ByteOrder>MSB</ByteOrder>
      </VRTRasterBand>
    </VRTDataset>

Then, display a sample of the map (it's a big old beastie) as follows:

require(raster)
forestCanopyIGH = raster("test.vrt")
plot(forestCanopyIGH,maxpixels=100*100)

I need help with the next step of displaying the unprojected version!

Many thanks,

 - Steve.


Steve Pickering
Assistant Professor
Kobe University
2-1 Rokkodai-cho
Nada-ku, Kobe
657-8501 Japan
pickering at penguin.kobe-u.ac.jp
http://www.stevepickering.net