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I'm using Environment Agency DTM LiDAR data which I import into Mathematica in ASCII format to produce ground surface models, sections, etc.

The process works fine, but I'm unclear whether the cell elevation values always relate to the easting and northing at the cell centroids or whether their plan positions are dictated by the header data XLLCORNER/XLLCENTER and YLLCORNER/YLLCENTER?

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XLLCENTER or XLLCORNER and YLLCENTERor YLLCORNER are parameters from the grid (think of it as an empty raster). Those are the coordinates from the origin of the grid and from them (plus CELLSIZE parameter) all the other coordinates in the grid can be known.

On the other hand, the elevation value in the DTM (think of it as a filled raster) is a property from the entire cell, and it is mostly/commonly represented by its centroid if vectorized.

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