> Agreed (I think you mean '0' is a valid array index). Yes, I meant '0' :)
> Note this is not quite 'drawing DEM in UTM mode' OK, thank you for clarifying it. > basically some fairly obscure USGS Topo files, that I doubt hardly anyone uses with viking. What does it mean for the future support of the format in Viking? Best regards, Kamil On Sat, Jan 18, 2020 at 7:51 PM Robert Norris <rw_nor...@hotmail.com> wrote: > > > 1. vikdemlayer.c:620 > > > >Here the code makes sure that array index is not out of bounds, but it > seems that the condition should be 'if(new < 0)' rather than 'if(new < 1)'. > '1' is a valid array index. > > Agreed (I think you mean '0' is a valid array index). > > Thus I also think instead of using > prevcolumn = g_ptr_array_index ( dem->columns, x+1); > explicitly use 0, so its: > prevcolumn = g_ptr_array_index ( dem->columns, 0 ); > > Similarly the upper bound should be explicit, so in a few lines further > down, instead of: > nextcolumn = g_ptr_array_index ( dem->columns, x-1); > it should be: > nextcolumn = g_ptr_array_index ( dem->columns, dem->n_columns-1); > > Note that having tried this (as in fixing it to use column 0) there > appears to be little difference in the end results. > > Further note that this is only for the DEM gradient drawing in getting a > colour by checking the change in elevation values. > Currently the code suffers from a small edge effect for drawing each DEM > file, as in working out the colour it only uses the current DEM file; as > opposed to attempting to get values from the neighbouring DEMs (i.e. the > elev at a location outside this DEM) to calculate the gradient across the > boundary. > > Depending on how simple this is to fix or if computationally significant, > I'll at least put a comment in the code about it. > > >2. vikdemlayer.c:787 > > >Here the code draws DEM in UTM mode and is again checking column index, > and I think that it again is making a mistake. The 'x > 0' condition > probably should be replaced with 'x >= 0', because '0' is still a valid > array index. > > Agreed it should be 'x >= 0'. > > Note this is not quite 'drawing DEM in UTM mode', this is for drawing when > the DEM data files themselves are in UTM format (as opposed to setting > Viking to draw in UTM mode). However such DEM files are only available if > you have configured viking compiling with '--enable-dem24k' and then using > a separate program 'sdts2dem' - basically some fairly obscure USGS Topo > files, that I doubt hardly anyone uses with viking. > > Indeed having never tried it before, I run the perl script (that Viking > would invoke) to acquire such DEM files but the website it accesses: " > geocomm.com" doesn't exist anymore. > > > As ever, thank you for taking the time to analyze and commit on the Viking > code. >
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