The gdal_translate program has an option to define an XML file with the necessary information to download an image using various web map server specifications. I am trying to download a file that should have a specific color table palette with 256 colors associated with it and one band of 8-bit (byte) values. But when I run gdal_translate on an XML file and download the file, the file only appears to have 3-band RGB values with no color table (when I look at the image attributes using gdalinfo).
For example, I have the following XML file I'm using to download an image:
<GDAL_WMS>
<Service name="AGS">
<ServerUrl>https://raster.nationalmap.gov/arcgis/rest/services/LandCover/USGS_EROS_LandCover_NLCD/MapServer</ServerUrl>
<ImageFormat>tiff</ImageFormat>
<Layers>show:6</Layers>
<BBoxOrder>xyXY</BBoxOrder>
<SRS>26917</SRS>
</Service>
<DataWindow>
<UpperLeftX>720586.0306923158900</UpperLeftX>
<UpperLeftY>3962270.5642631231000</UpperLeftY>
<LowerRightX>723891.5076759960500</LowerRightX>
<LowerRightY>3960158.2215603264000</LowerRightY>
<SizeX>164</SizeX>
<SizeY>105</SizeY>
</DataWindow>
<UnsafeSSL>true</UnsafeSSL>
</GDAL_WMS>
I save this file as "nlcd.xml". Then I run the following command:
gdal_translate -of GTiff "F:\temp\nlcd.xml" "f:\temp\r.nlcd.tif"
The file is downloaded and I am able to view the image using various methods. However, when I run gdalinfo on the image, there are 3 bands with no color table defined:
gdalinfo f:\temp\r.nlcd.tif
Driver: GTiff/GeoTIFF
Files: f:\temp\r.nlcd.tif
Size is 164, 105
Coordinate System is:
PROJCS["NAD83 / UTM zone 17N",
GEOGCS["NAD83",
DATUM["North_American_Datum_1983",
SPHEROID["GRS 1980",6378137,298.257222101,
AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6269"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4269"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-81],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH],
AUTHORITY["EPSG","26917"]]
Origin = (720586.030692315890000,3962270.564263123100000)
Pixel Size = (20.155347461464373,-20.117549550444597)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left ( 720586.031, 3962270.564) ( 78d33'34.26"W, 35d46'47.19"N)
Lower Left ( 720586.031, 3960158.222) ( 78d33'36.36"W, 35d45'38.69"N)
Upper Right ( 723891.508, 3962270.564) ( 78d31'22.72"W, 35d46'44.50"N)
Lower Right ( 723891.508, 3960158.222) ( 78d31'24.85"W, 35d45'36.00"N)
Center ( 722238.769, 3961214.393) ( 78d32'29.55"W, 35d46'11.60"N)
Band 1 Block=164x16 Type=Byte, ColorInterp=Red
Band 2 Block=164x16 Type=Byte, ColorInterp=Green
Band 3 Block=164x16 Type=Byte, ColorInterp=Blue
I expected to see one band with a color table defined-something like the following on a file I previously downloaded using another method:
gdalinfo "F:\temp\nlcd2006.tif"
Driver: GTiff/GeoTIFF
Files: F:\temp\nlcd2006.tif
Size is 1296, 1598
Coordinate System is:
PROJCS["WGS 84 / UTM zone 10N",
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.2572235604902,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433],
AUTHORITY["EPSG","4326"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-123],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AUTHORITY["EPSG","32610"]]
Origin = (464430.000000000000000,4363320.000000000000000)
Pixel Size = (30.000000000000000,-30.012515644555695)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
COMPRESSION=PACKBITS
INTERLEAVE=BAND
Corner Coordinates:
Upper Left ( 464430.000, 4363320.000) (123d24'47.61"W, 39d25' 7.21"N)
Lower Left ( 464430.000, 4315360.000) (123d24'38.52"W, 38d59'11.44"N)
Upper Right ( 503310.000, 4363320.000) (122d57'41.57"W, 39d25' 9.83"N)
Lower Right ( 503310.000, 4315360.000) (122d57'42.41"W, 38d59'14.02"N)
Center ( 483870.000, 4339340.000) (123d11'12.52"W, 39d12'11.43"N)
Band 1 Block=1296x1 Type=Byte, ColorInterp=Palette
Color Table (RGB with 256 entries)
0: 0,0,0,255
1: 0,250,0,255
2: 0,0,0,255
3: 0,0,0,255
4: 0,0,0,255
5: 0,0,0,255
6: 0,0,0,255
7: 0,0,0,255
8: 0,0,0,255
9: 0,0,0,255
10: 0,0,0,255
11: 71,107,161,255
12: 209,222,250,255
13: 0,0,0,255
14: 0,0,0,255
15: 0,0,0,255
16: 0,0,0,255
17: 0,0,0,255
18: 0,0,0,255
19: 0,0,0,255
20: 0,0,0,255
21: 222,201,201,255
22: 217,148,130,255
23: 237,0,0,255
24: 171,0,0,255
25: 0,0,0,255
26: 0,0,0,255
27: 0,0,0,255
28: 0,0,0,255
29: 0,0,0,255
30: 0,0,0,255
31: 179,173,163,255
32: 250,250,250,255
...
My question is: Is there a way to export a GeoTIFF with a single band and a color palette from a web service using gdal_translate instead of exporting the RGB values in 3 separate bands?
Best Answer
You can now accomplish this with rasterio. From the example at: https://rasterio.readthedocs.io/en/latest/topics/color.html
where you would replace the example's dictionary -- which only has entries for indexes 0 and 255 -- with your own colormap dictionary.
I have found that you can supply a dictionary with 3-member tuples (R, G, B) and rasterio will give the transparency ("A") channel a value of 255.