[GRASS-dev] [GRASS GIS] #2992: r3.null creates a lot of new unexpected null cells likely by creating a null tile

[GRASS GIS]

#2992: r3.null creates a lot of new unexpected null cells likely by creating a
null tile
-------------------------------------------------+-------------------------
 Reporter:  wenzeslaus                           |      Owner:  grass-dev@…
     Type:  defect                               |     Status:  new
 Priority:  major                                |  Milestone:  7.0.4
Component:  Raster3D                             |    Version:  unspecified
 Keywords:  r3.null, NULLs, tiles,               |        CPU:  Unspecified
  Rast3d_flush_tiles_in_cube, data loss          |
 Platform:  Unspecified                          |
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 When running `r3.null` I get a lot of NULL cells as a result regardless of
 input. When I show it in 3D as slices one part of the raster is missing.
 It looks like all values in one tile are NULLs (the tile is a NULL tile).

 It seems that the computational region is important. I don't get the
 behavior with arbitrary region.

 {{{
 > g.region -3 n=220180 s=219900 w=638360 e=638720 t=153 b=106 res=2 res3=2
 }}}

 When replacing value by NULL, I get more NULL cells than expected:

 {{{
 > r3.mapcalc --o expr="test_1 = float(col() + row() + depth())"
 > r3.univar map=test_1
 total null and non-null cells: 604800
 total null cells: 0
 ...
 > r3.null map=test_1 setnull=10
 > r3.univar map=test_1
 total null and non-null cells: 604800
 total null cells: 40356
 ...
 }}}

 When replacing NULLs by value, I get a lot of NULL values.

 {{{
 > r3.mapcalc --o expr="test_1 = float(col() + row() + depth())"
 > r3.univar map=test_1
 total null and non-null cells: 604800
 total null cells: 0
 ...
 > r3.null map=test_1 null=10
 > r3.univar map=test_1
 total null and non-null cells: 604800
 total null cells: 40320
 ...
 }}}

 There is a lot of different `Rast3d_*lock*()` calls in the code but when I
 comment out the call of `Rast3d_flush_tiles_in_cube()`, I get the right
 results (there is `Rast3d_flush_all_tiles()` at the end). Documentation of
 `Rast3d_flush_tiles_in_cube()` says ''tiles which are not stored in the
 cache are written as NULL-tiles.''

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2992>
GRASS GIS <https://grass.osgeo.org>