[Gdal-dev] [GDAL_Contours]Different gridcellsizes

[Rob Cairns]

Hi Frank and Paul

I hope you don't mind me chipping in on this discussion. I am also 
currently using the gdal_contour function via MapWindow and it is a 
fantastic utility. However, from previous correspondence with Paul on the 
MapWindow forum, we noticed that gdal seems to push the contour up and to 
the right of the cell. The attached hypothetical ASCII grid and picture 
will show what I mean. In the picture, the blue line is where I would 
expect the contour to be and the red line is where gdal actually draws the 
contour - on the top and right of the cells with the value of the contour 
elevation. I wondered if this was a bug or whether I'm missing something 
the function "saddles" between elevations.

Regards Rob


 
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