Hanlie wrote: > >> At this point, g.region reports 1146474 cells in the region, while I > >> have 1146370 lines of coordinates in my file. ... > > So it looks like there are about 100 coordinates missing from the ASCII > > ASCII file.
0.01% .. > Maybe "holes" in the data? perhaps this: https://trac.osgeo.org/grass/ticket/123 ?? > I was thinking perhaps importing the points as vectors, converting > them to raster and then doing a nearest neighbour or IDW interpolation > to fill the gaps. At least then I'll be able to see where the gaps are > and limit the interpolated pixels using a mask? No need to do anything different to find the missing pixels. Inspecting the output of r.univar with r.in.xyz's method=n maps can be very useful for troubleshooting. from the help page: Gridded data If data is known to be on a regular grid r.in.xyz can reconstruct the map perfectly as long as some care is taken to set up the region correctly and that the data's native map projection is used. A typical method would involve determining the grid resolution either by examining the data's associated documentation or by studying the text file. Next scan the data with r.in.xyz's -s (or -g) flag to find the input data's bounds. GRASS uses the cell-center raster convention where data points fall within the center of a cell, as opposed to the grid-node convention. Therefore you will need to grow the region out by half a cell in all directions beyond what the scan found in the file. After the region bounds and resolution are set cor- rectly with g.region, run r.in.xyz using the n method and verify that n=1 at all places. r.univar can help. Once you are confident that the region exactly matches the data proceed to run r.in.xyz using one of the mean, min, max, or median methods. With n=1 throughout, the result should be identical regardless of which of those methods are used. with the "n" map you might use r.mapcalc to extract the NULL cells as some value, then r.out.xyz or r.to.vect on th extracts to highlight where they are. Or maybe you get lucky with r.colors with "nv" set to bright magenta on the original data. Hamish _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
