[gdal-dev] [EXT] Re: [EXT] Re: [Doc] gdal_calc.py extent option

[Matt.Wilkie]

The definitions are correct. For the union you want a rectangle (or polygon) that's larger than the input, indeed. But you want the smallest of those rectangles, because there's an infinity of them. The larger ones would cover an arbitrary area of the plane (or the globe, if you want).

Same for the intersection. You want the largest polygon equal to or contained in the inputs. Otherwise a smaller answer could just as well be a single point (or empty), even in nondegenerate cases.

Please verify I’m parsing these words the way you intend. To me it sounds like you’re saying the labels for these figures should be reversed? (for gdal)

[cid:image003.png at 01D8E3BA.985DDCA0]


-Matt
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