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
_______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
