r.to.vect fails on a properly thinned tif via r.thin/r.null

[hbgdal]

Hi, This happens only on a small number of tif files. Most of the tif files are processed successfully. Commands to reproduce problem with 7.2.0 are pasted below. I would appreciate any workaround/patch(for 7.2.0 or any other version) for this fix.

Problem: For some tifs, the r.to.vect fails complaining that the image needs to be thinned, and then hangs with a message about busy SQLite DB.

Expected behavior: Either r.to.vect should extract lines from thinned image, or r.thin should thin the image further.

Env: Ubuntu 14.04. 7.2.0 compiled

Commands to run: #This is "binary" image with two colors black and white r.in.gdal input=/tmp/grass_problem.tif output=grass_problem location=grass_problem

#Replace "white" color with null for r.thin. r.null --verbose map=grass_problem@PERMANENT setnull=255

#r.thin succeeds in less than 10 iterations.(See output below) r.thin --verbose input=grass_problem@PERMANENT output=grass_thin

#r.to.vect complains. r.to.vect --verbose input=grass_thin@PERMANENT output=vec_lines type=line

r.thin output showing success ====

Raster map <grass_problem@PERMANENT> - 4028 rows X 3288 columns Bounding box: l = 3, r = 3284, t = 7, b = 4028 Pass number 1 Deleted 240415 pixels Pass number 2 Deleted 5154 pixels Pass number 3 Deleted 115 pixels Pass number 4 Deleted 5 pixels Pass number 5 Deleted 0 pixels Thinning completed successfully. Output map 4028 rows X 3288 columns Window 4028 rows X 3288 columns (Thu Aug 3 11:17:10 2017) Command finished (2 sec)

r.to.vect output showing failure

r.to.vect --verbose input=grass_thin@PERMANENT output=vec_lines type=line Using native format Extracting lines... Crowded cell at (362.125000, 12883.540000): row 424, col 1721, count 7 ERROR: Raster map is not thinned properly. Please run r.thin. WARNING: Busy SQLITE db, already waiting for 10 seconds. ....

[hbgdal]

part 00 of gzipped tif file

[hbgdal]

part 01 of gzipped tif file