Adding band to existing GeoTIFF using GDAL

Question

This seems like it should be straightforward but I can't for the life of me figure it out.

Given an existing GeoTIFF containing a single band, how can you add another band to that GeoTIFF? Is the only way to do this to use GDALCreate() to create a new output file with an additional band and then copy the existing band from the original file to the new file? That's the only solution I've come up with so far but it just seems like there should be a simple way to add a band to the existing dataset.

• Jackie: Hi @TheOx, I have a same problem. I want to make a composite image color from band 2,3,4 of LDCM single bands. Do you have solution for your question yet?
• TheOx: @Jackie see kyle's comment in the accepted answer about using the vrt driver to create a copy, add a band, then create a copy of that back to a geotiff with the GeoTiff driver.

Answer 1

To expand on Luke's answer and provide a concrete example in Python, here's a snippet that adds an alpha band to a source raster and saves it as a PNG.

from osgeo import gdal
src_ds = gdal.OpenShared(input_path)
mask_ds = gdal.OpenShared(mask_path)
mask = mask_ds.GetRasterBand(1).ReadAsArray()
tmp_ds = gdal.GetDriverByName('MEM').CreateCopy('', src_ds, 0)
tmp_ds.AddBand()
tmp_ds.GetRasterBand(4).WriteArray(mask)
dst_ds = gdal.GetDriverByName('PNG').CreateCopy(output_path, tmp_ds, 0)
del dst_ds

I used the MEM driver instead of VRT since the latter does not support WriteRaster() and WriteArray() (error "Writing through VRTSourcedRasterBand is not supported."). Using the vrt driver might still be possible through some other methods, I suppose.

Answer 2

The solution, if the driver supports it, is to call GDALOpen() with GA_Update access then use GDALAddBand or GDALDataset::AddBand. However, the geotiff driver doesn't support AddBand.

• user10353: Very few drivers support add band, I don't believe the geotiff driver does. The only one I know that supports it is the vrt.
• TheOx: Well @kyle is right - the geotiff driver doesn't support AddBand, but the method in this answer is correct if the driver supports it and was what I was looking for so I'm accepting it.
• user2856: Doh! Forgot about that little detail. @TheOx I don't think you should accept my answer as it is not correct re. the orig question which specifically related to geotiffs.
• TheOx: @Luke: Edit your answer to specify that's the general solution if the driver supports it and I'll accept it. There appears to be no other way to do this for GeoTiff short of the method in my original question.
• user10353: Use the vrt driver, CreateCopy(), AddBand(), CreateCopy() with Geotiff Driver.

Answer 3

The Geotiff driver does not support the AddBand() method. To see this, get the last GDAL error just after the AddBand() line:

tmp_ds.AddBand();
String lastError = gdal.GetLastErrorMsg();
// lastError: "MyGeo.tif: Dataset does not support the AddBand() method."

Please note that my code is in Java but you already get the idea.

If you are bound to the Geotiff format then it seems creating the needed band/bands up front when initializing the Dataset is the way to go.