Hi List, I tried my command on GDAL 3.8.4, released 2024/02/08. And the results are the same. The lowest value is still incorrect.
I can't imagine this is a bug that was never noticed before. So I assume I'm doing something wrong. But I can't figure it out. Please give me some advice. Regards, Paul Op vr 5 apr 2024 om 10:27 schreef Paul Meems <bontepaar...@gmail.com>: > Hello List, > > I have a Surfer grid which I want to convert into polygons using > gdal_contour. > The min value of the lowest polygon is 0 which I didn't expect. > In the next step, I calculate the average of the min and max values, and > in this case that average is wrong. > > These are the values of the grid: > Grid Size (X*Y): 113 x 121 > NoData Value: 1.70141E+38 > Minimum: 105000 > Maximum: 133000 > > This is my command: > gdal_contour -p -f "ESRI Shapefile" -fl -97000 -37000 23000 83000 89000 > 95000 101000 107000 113650 121000 129000 137000 143000 149000 155000 215000 > 275000 335000 -amin Min -amax Max "Surfer.grd" "tmp3p4f4i.shp" > > As you can see, the lowest value of the grid (105000) is between the > values 101000 and 107000. > So I would expect to have the min value of the shapefile be 101000 and the > max value 107000. > > But the result is: > [image: image.png] > Min is 0 and max is 107000. > > I also tried setting the lowest value of the grid to 107000 (one of the > level values) but that also resulted in a min value of 0. > > The polygons themselves are OK, just the min value of the lowest value is > incorrect. > > I'm using GDAL 3.6.3, released 2023/03/07 on Windows. > > Why is this happening? > Do I need to set an additional argument? > > Please advise. > > With regards, > > Paul >
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