[Qgis-user] Clipping a Raster with a Mask Layer - update - possible bug

[Randal Hale]

So I've got an update on this.

If I run this with the command line (gdal 2.1):

gdalwarp -cutline acid_forest_buffer.shp low_east.tif output.tif
/Processing input file low_east.tif.//
//Using internal nodata values (e.g. -3.40282e+38) for image low_east.tif.//
//Warning 1: Self-intersection at or near point 2309.5402184630693 
1121.2793755624425//
//ERROR 1: Cutline is not valid after transformation/

I had one community member confirm the clip works in 2.14.1. I think 
ultimately this is a gdal version problem - sort of.

If I look at the shapefile in QGIS I get an error using the topology 
tools looking for overlaps. I seem to have 2 multipolygons in this data. 
I clean those up and the tool runs as expected.

Is there something with gdal 2.1 that chokes with a multipolygon in 
running this type of clip against a raster?


On 10/07/2016 09:27 AM, Randal Hale wrote:
>
> I've tried this on:
>
>   * 2.14.6 on Windows
>   * 2.16.3 on Linux
>   * Master on Linux
>
> Dropbox Link: 
> https://www.dropbox.com/sh/zg8miobad8ax0ef/AABXzPzTd8920I248_IprKjba?dl=0
>
> I have a raster and polygons. All matching in projection. M one worry 
> is the raster is a float32 tiff and something it wrong with it. I 
> didn't create the raster but I am trying to help someone work their 
> way through this exercise for a College Class.
>
> When I use the processing tool to clip the raster with the vector I 
> get an output image that in the legend shows the values as being nan - 
> which I guess is null. No matter what I do - there is no clip. Just a 
> large image that is black or nan (null).
>
> Thoughts? I'm stuck. I don't know if I'm seeing a bug or I've got a 
> bad image. The person originally working through this said it all 
> works correctly with 2.8 (but I haven't attempted that version as of 
> yet).
>
> Randy
>
> -- 
> ------------------------------------------------
> Randal Hale
> North River Geographic Systems, Inc
> http://www.northrivergeographic.com
> 423.653.3611rjhale at northrivergeographic.com
> twitter:rjhalehttp://about.me/rjhale
> http://www.northrivergeographic.com/introduction-to-quantum-gis
> https://www.facebook.com/NRGSInc

-- 
------------------------------------------------
Randal Hale
North River Geographic Systems, Inc
http://www.northrivergeographic.com
423.653.3611 rjhale at northrivergeographic.com
twitter:rjhale     http://about.me/rjhale
http://www.northrivergeographic.com/introduction-to-quantum-gis
https://www.facebook.com/NRGSInc

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