Hi all, I am trying to use r.terraflow now as well to analyse a very large dataset. However, I run into the same issue as the OP. I get millions of warning messages that are not really relevant, because a negative tci is in my eyes just valid, however, adding an hour to my initial test run on a smaller sample.
I think the check on line 143 of sweep.cc should see if the flow or the slope are negative (giving rise to the log of a negative number resulting in an error). I am not sure yet what a negative tci means, but a small flow with a large slope will result in a ratio smaller than 1 giving a negative value for the logarithm taken. Has any work been done on this? Sincerely, Roderik Ludwig M Brinckmann wrote: > > Looking through the code of r.terraflow I discovered that there is one > compile time only option that significantly reduces/improves the > performance > of r.terraflow. At the moment builds produce the less performant version > by > default, which for such a long running program is not good. Only those who > read and modify the source code can get the faster version. > > options.h, l. 47, #defines OUTPUT_TCI by default, causing additional files > generated and in my case a significant (I think millions) number of error > messages from this TCI option from sweep.cc line 143 (tci negative). > > Not being a GIS person I have no idea what the error means, the output > from > r.terraflow seemed to correlate with reality despite the message, and even > the author of this bit seemed not sure what the error signified: see line > 141: is this true?. Printing the error a zillion times added a night to my > program run. > > -- View this message in context: http://www.nabble.com/r.terraflow-performance-tweak-tp3918075p19140066.html Sent from the Grass - Dev mailing list archive at Nabble.com. _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
