[GRASS-dev] [GRASS GIS] #3387: r.to.vect fails on a properly thinned tif via r.thin/r.null

[GRASS GIS]

#3387: r.to.vect fails on a properly thinned tif via r.thin/r.null
--------------------------+-------------------------
  Reporter:  hbgdal       |      Owner:  grass-dev@…
      Type:  defect       |     Status:  new
  Priority:  normal       |  Milestone:  7.2.2
 Component:  Raster       |    Version:  7.2.0
Resolution:               |   Keywords:  r.to.vect
       CPU:  Unspecified  |   Platform:  Linux
--------------------------+-------------------------
Description changed by martinl:

Old description:

> 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 at PERMANENT setnull=255
>
> #r.thin succeeds in less than 10 iterations.(See output below)
> r.thin --verbose input=grass_problem at PERMANENT output=grass_thin
>
> #r.to.vect complains.
> r.to.vect --verbose input=grass_thin at PERMANENT output=vec_lines type=line
>

> ===== r.thin output showing success ====
> Raster map <grass_problem at 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 at 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.
> ....

New description:

 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 at PERMANENT setnull=255

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

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


 ===== r.thin output showing success ====
 Raster map <grass_problem at 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 at 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.
 ....
 }}}

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3387#comment:2>
GRASS GIS <https://grass.osgeo.org>