Error clipping raster in QGIS?

Asked Mar 13 '20 at 14:36

Active Mar 13 '20 at 14:39

Viewed 79 times

I am trying to use a polygon shapefile to clip a raster, but it gives me "Clipping Error 1: Cutline polygon is invalid", and a blank raster as output.

This is similar to this question, but the answers suggested there don't seem to work. Both layers are in the same projection. I have checked and fixed the shapefile geometry, and I have tried buffering the polygons by 0m. Neither resolve the error. Is there anything else I can attempt? I was wondering about dissolving the shapefile before clipping? However, it has ~600k polygons, so I hope to avoid a step that is likely to take a long time.

edited Mar 13 '20 at 14:39

asked Mar 13 '20 at 14:36

EcologyTom

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Are both the raster and the shapefile in the same projection? – MappaGnosis Mar 13 '20 at 14:38
@MappaGnosis, yes, sorry, detail added to the question. – EcologyTom Mar 13 '20 at 14:39
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Wait, you're trying to clip a single raster by 600 k shapes? Have you tried using only the necessary subset of polygons? – Erik Mar 13 '20 at 14:40
@Erik - they are all necessary. – EcologyTom Mar 13 '20 at 14:41
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So they are all within the area of the raster? How is the features size compared to the raster cell size? – Erik Mar 13 '20 at 14:45
@Erik, yes all within the raster area. The polygons are variable in size, but larger than an individual raster cell. – EcologyTom Mar 13 '20 at 14:48
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Have you checked the geometry after attempting to try to repair it? – Erik Mar 13 '20 at 14:49
@Erik, yes, check geometry states there are no errors. – EcologyTom Mar 13 '20 at 14:50
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What about creating subsets, if you're unwilling to dissolve? – Erik Mar 13 '20 at 14:53
@Erik, you think it might just be the number of polygons that is causing the issue? – EcologyTom Mar 13 '20 at 14:57
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Not really, but this way you can narrow down the faulty polygons. – Erik Mar 13 '20 at 14:58
@Erik, so you think that the check and fix geometry steps just didn't work correctly? – EcologyTom Mar 13 '20 at 15:00
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This is almost always the case in my experience. It also depends on, which tools your exactly used. – Erik Mar 13 '20 at 15:08
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Forward systematically: Does it work with 1 polygon? 20? 100 - 1000 - 5000 -10000? When you get the first failure try to isolate the reason. – user30184 Mar 13 '20 at 15:17

Error clipping raster in QGIS?

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