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I'm fairly new to GDAL and I have some GeoTIFF files that I would like to highlight some bodies of water on. I have gotten pretty far, but I have one problem. The only way I am able to highlight a body of water is with gdal.warp and cutlineDSName (I'm using osgeo gdal in Python), which is great, but it cuts out the rest of the image completely. What I would like to do is just draw a line, rather than cut the surrounding area out.

Can anyone help me out?

I'm hoping it's a flag that I am missing somewhere.

code below.

tifFile = 'C:\\merged.tif'
shapeFile = 'C:\shapefile.shp'
outFile = 'C:\\merged_and_cropped.tif'

input_raster = tifFile
output_raster = outFile
input_kml = shapeFile

ds = gdal.Warp(output_raster,
              input_raster,
              format = 'GTiff',
              cutlineDSName = shapeFile,
              cropToCutline=True,
              dstNodata = 0)
ds = None
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3

you can use gdal_rasterize to do this.

It will let you 'burn' values into a raster from lines or polygons. In some cases it'll create a new raster but it might update your existing raster, so take a backup of your raster before experimenting ;-)

An example (3 bands, for aerial imagery for example) from that site which draws a line/polygon from outline.shp into work.tif . It'll use Red (255 0 0).

gdal_rasterize -b 1 -b 2 -b 3 -burn 255 -burn 0 -burn 0 -l mask outline.shp work.tif

If your raster is a polygon the interior will be filled, if you're after an outline you need to convert the polygon to a line first.

Depending on output resolution, you could also get a thicker outline by buffering the cut line.

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3
  • Thanks! I got the interior filled, as you stated. Now I just need to get the outline. Sorry, I am very new to this - when you say to convert the polygon to a line, do you mean to do that in the shapefile? – jonesy19 Jul 17 '18 at 19:56
  • see this answer. It's seven years old old, but this hasn't changed much since then and should still work. – Steven Kay Jul 17 '18 at 20:37
  • Another question - I am trying to get a thicker outline, as you suggested above. You mentioned I could do that by buffering the cut line. How would I do that? I have tried -l buffer_lines, but that doesn't work. I also tried to modify the .shp file by putting a thicker line in, but that also doesn't work. Any thoughts? – jonesy19 Aug 23 '18 at 16:58

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