gdalgdalwarpnodatanullsetnull
I need to set a 3 band multiband raster (GeoTIff) where band 1 = 0 AND band 2 = 0 AND band 3 = 0 then this is no data (0,0,0 is No Data). Not OR in each band but AND across the 3 bands.
I think it is GDALWARP -dstnodata but am unsure of the syntax.
How do I set the No Data value as 0,0,0 in the header?
What you want to do is Set Raster Properties in a script or change it manually in ArcCatalog. This will not create a new raster or even take very long.
In python it's a bit tricky:
import sys, os, arcpy
InFolder = sys.argv[1]
arcpy.env.workspace = InFolder
for Ras in arcpy.ListRasters():
arcpy.AddMessage("Processing " + Ras)
arcpy.SetRasterProperties_management(Ras,nodata="1 0;2 0;3 0")
Because the nodata is way down the list I find it easier to specify that; the parameters are Band Value;Band Value;... until all the bands are addressed. If you are likely to have more bands (or less) in the same folder then you will have to use arcpy.Describe and the bandCount property to set the null for the correct number of bands:
import sys, os, arcpy
InFolder = sys.argv[1]
arcpy.env.workspace = InFolder
for Ras in arcpy.ListRasters():
arcpy.AddMessage("Processing " + Ras)
desc = arcpy.Describe(Ras)
if desc.bandCount == 3:
arcpy.SetRasterProperties_management(Ras,nodata="1 0;2 0;3 0")
elif desc.bandCount == 4:
arcpy.SetRasterProperties_management(Ras,nodata="1 0;2 0;3 0;4 0")
elif desc.bandCount == 1:
arcpy.SetRasterProperties_management(Ras,nodata="1 0")
In ArcCatalog, right click on the layer and go to properties:
hit the edit button:
Enter the values then hit OK to dismiss the NoData editor and OK to enforce the change.
Now the raster will display nothing in ArcMap where the cell value is 0,0,0.
Can be done fairly easy. First, create the dataset:
drv = gdal.GetDriverByName("GTiff")
ds = drv.Create("name.tif", width, height, 6, gdal.GDT_Float32)
You then need to set the geotransform using ds.SetGeoTransform where the argument is a six element tuple: (upper_left_x, x_resolution, x_skew, upper_left_y, y_skew, y_resolution)
Set the projection using ds.SetProjection, argument is the way string, then
Write the array for the first band:
ds.GetRasterBand(1).WriteArray(arr)
That should be enough to get you going. If the purpose is just to reproject the data, then you could look at using an in memory dataset
Best Answer
The syntax is documented on the manual page https://www.gdal.org/gdalwarp.html as
On Windows it means double quotation marks, on Linux I guess that single quotes work. So in theory you would do it like this
However, the target format must also support different nodata values for each band and GeoTIFF is not such format.
So you can't do what you want with GeoTIFF because the one and only supported nodata value gets just overwritten and finally all bands use the nodata value of the blue band as nodata.
If you use GDAL based software for reading your data then GDAL virtual raster (VRT) might be the best option. As you can see it can handle band specific nodata.