[GRASSLIST:512] Problems with r.thin and r.line

[Jorge Samuel Mendes de Jesus]

I am experience some problems with r.thin and r.line. I am creating maps
with contour lines of altitudes from scanned maps and I need to run
r.thin and then r.line. The problem is that r.line says that the maps
are not properly thin and gives problems in cells.
I have tryed to replace any NULL values that could exist to 0 or 1,
passing the maps to  separate  color channels, despite all of this
nothing seems to work.
Any one hsa experience in this problems. I would like to thank for the
help that michelle rocc has given

Jorge