On Monday 23 June 2008, Markus Neteler wrote: > On Mon, Jun 23, 2008 at 1:52 PM, Glynn Clements > > <[EMAIL PROTECTED]> wrote: > > Markus Neteler wrote: > >> > And i.smap is gibberish; e.g. write_img() calls G_is_c_null_value() on > >> > "char"s, so that module probably hasn't worked since 4.x. > >> > >> i.smap works, I have tested it recently and also others use it > >> regularly.
This is very troubling, as I have been using i.smap for sometime now (GRASS64-svn), and the output has thus far been convincing. However, I have only been using it with CELL input maps... > > Oh, it may produce output, but not necessarily correct output. > > > > Specifically, write_img() does: > > > > if(G_is_c_null_value((CELL *)&img[row][col])) > > G_set_c_null_value(&files->cellbuf[col], 1); Just words, but this again points to the dire need for a comprehensive test suite. > > But "img" is a "unsigned char **", i.e. a 2D array of bytes. The test > > will only succeed if the array contains the sequence 00,00,00,80 (for > > little-endian systems) or 80,00,00,00 (big-endian systems). I suspect > > that the test was originally against zero, but it was incorrectly > > changed when null support was added. > > > > If that's the case, the net result will be that it writes garbage > > where it should be writing nulls, and occasionally writes nulls where > > it shouldn't. Is there any way to evaluate this? Would this bug only affect input maps that are FP? > That sounds quite ugly. But from looking at the code: is a major > rewrite needed to fix that? Since we "just" write out classes? > > > Beyond that, it seems fairly straightforward. I have committed an > > update which compiles without warning, but hasn't been tested. > > Backported. But... > > >> Any opinions on > >> i.gensig > >> i.gensiset > >> ? Both are used for supervised classification where you have training > >> areas instead of just looking at the pixels as does i.cluster. > > > > Looking briefly at i.gensig, the algorithm seems to be quite heavily > > based upon categories (e.g. using the Cell_stats stuff), so it would > > need to be substantially re-written to support FP in any meaningful > > sense. I have never been able to use the GRASS classification routines on FP maps- usually just results in a map of NULL data or 0. Dylan > ... without an update to i.gensigset I cannot test the FP capabilities of > i.smap. It seems that it was cloned from i.gensig. > > Markus -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev