Texture Painting: Fix Seam Bleeding of Non-Manifold Sections of Mesh #105336

Jeroen Bakker · 2023-03-01T10:36:25+01:00

Jeroen Bakker commented

2023-03-01 10:36:25 +01:00

Fix seam bleeding of non-manifold sections of the mesh, by copying pixels
that are covered by the brush stroke.

As manifold parts are already handled, the pixel copying solution can be
very straight forward.

Pixels are copied from the same tile. So we don't need a mechanism that
copies and merges pixels from other tiles.
Pixels are copied from the closest pixel that is being painted on. We
don't need to consider that that pixel can be in different areas of the
tile.

When we copy a pixel, we find the closest pixel in UV space that is being
directly influenced by a paint brush. We also look for the second closest
pixel, which is still a neighbor from the closest pixel. We can mix both
pixels together and store it in the destination. A mix factor is calculated
using the closest non manifold edge as a guidance.

The result of this step is a list of copy and mix commands that can be
executed to fix the seam bleeding for non-manifold sections of the mesh.

Destination	Source 1	Source 2	Mix factor
1780,1811	1780,1810	1779,1810	0.000000
1781,1811	1781,1810	1782,1811	0.168627
1828,1811	1828,1810	1827,1811	0.156863
1829,1811	1829,1810	1828,1810	0.188235
1830,1811	1830,1810	1829,1810	0.188235
1831,1811	1831,1810	1830,1810	0.188235
1832,1811	1832,1810	1831,1810	0.188235
1833,1811	1832,1810	1832,1810	0.000000

In the end we go over this list mix the sources and store the result at
the destination.

tile_buffer[destination] = mix(tile_buffer[source_1],
                               tile_buffer[source_2],
                               mix_factor);

Encoding
When using a large textures or large seam margins this table can grow
large and reduce performance as data retrieval is slower, than the
operations it has to perform. To improve the performance we encode the
table so less data retrieval needs to be done.

first DeltaCopyPixelCommand is delta encoded from
CopyPixelGroup#start_destination and start_source_1. The others
are delta encoded from the previous DeltaCopyPixelCommand.
For performance reasons PixelCopyGroup#pixels are ordered from
destination (left to right) for each row a new group would be created
as the delta encoding most likely doesn't fit. When pixels cannot be
delta encoded a new group will also be created.

Compression rate
When using Suzanne the compression rate is around 36% when using a seam
margin of 4 pixels. The compression rate may vary depending on seam
margin and model. For Suzanne the compression rate was around 36% for
various resolutions.

Resolution	Margin	Decoded size	Encoded size	Compression
2048x2048	4 px	353.052	128.101	36%
4096x4096	4 px	700.140	255.137	36%
8192x8192	4 px	1.419.320	513.802	36%
2048x2048	8 px	721.084	193.629	26%
4096x4096	8 px	1.444.968	388.110	26%

Fix seam bleeding of non-manifold sections of the mesh, by copying pixels that are covered by the brush stroke. As manifold parts are already handled, the pixel copying solution can be very straight forward. * Pixels are copied from the same tile. So we don't need a mechanism that copies and merges pixels from other tiles. * Pixels are copied from the closest pixel that is being painted on. We don't need to consider that that pixel can be in different areas of the tile. When we copy a pixel, we find the closest pixel in UV space that is being directly influenced by a paint brush. We also look for the second closest pixel, which is still a neighbor from the closest pixel. We can mix both pixels together and store it in the destination. A mix factor is calculated using the closest non manifold edge as a guidance. The result of this step is a list of copy and mix commands that can be executed to fix the seam bleeding for non-manifold sections of the mesh. | Destination | Source 1 | Source 2 | Mix factor | | ----------- | -------- | -------- | ---------- | | 1780,1811 | 1780,1810| 1779,1810| 0.000000 | | 1781,1811 | 1781,1810| 1782,1811| 0.168627 | | 1828,1811 | 1828,1810| 1827,1811| 0.156863 | | 1829,1811 | 1829,1810| 1828,1810| 0.188235 | | 1830,1811 | 1830,1810| 1829,1810| 0.188235 | | 1831,1811 | 1831,1810| 1830,1810| 0.188235 | | 1832,1811 | 1832,1810| 1831,1810| 0.188235 | | 1833,1811 | 1832,1810| 1832,1810| 0.000000 | In the end we go over this list mix the sources and store the result at the destination. ``` tile_buffer[destination] = mix(tile_buffer[source_1], tile_buffer[source_2], mix_factor); ``` **Encoding** When using a large textures or large seam margins this table can grow large and reduce performance as data retrieval is slower, than the operations it has to perform. To improve the performance we encode the table so less data retrieval needs to be done. * first `DeltaCopyPixelCommand` is delta encoded from `CopyPixelGroup#start_destination` and `start_source_1`. The others are delta encoded from the previous `DeltaCopyPixelCommand`. * For performance reasons PixelCopyGroup#pixels are ordered from destination (left to right) for each row a new group would be created as the delta encoding most likely doesn't fit. When pixels cannot be delta encoded a new group will also be created. **Compression rate** When using Suzanne the compression rate is around 36% when using a seam margin of 4 pixels. The compression rate may vary depending on seam margin and model. For Suzanne the compression rate was around 36% for various resolutions. | Resolution | Margin | Decoded size | Encoded size | Compression | | ---------- | ------ | ------------ | ------------ | ----------- | | 2048x2048 | 4 px | 353.052 | 128.101 | 36% | | 4096x4096 | 4 px | 700.140 | 255.137 | 36% | | 8192x8192 | 4 px | 1.419.320 | 513.802 | 36% | | 2048x2048 | 8 px | 721.084 | 193.629 | 26% | | 4096x4096 | 8 px | 1.444.968 | 388.110 | 26% |

non-manifold.mp4

5.2 MiB

Jeroen Bakker added 1 commit 2023-03-01 10:37:09 +01:00

8dccfd380c Merged from https://archive.blender.org/developer/D16963

Jeroen Bakker added the

Module

Sculpt, Paint & Texture

label 2023-03-01 10:40:54 +01:00

Jeroen Bakker added this to the 3.6 LTS milestone 2023-03-01 10:40:58 +01:00

Jeroen Bakker added this to the Sculpt, Paint & Texture project 2023-03-01 10:41:06 +01:00

Jeroen Bakker self-assigned this 2023-03-01 10:41:14 +01:00

Jeroen Bakker added 1 commit 2023-03-01 10:43:06 +01:00

2c14eb34d1 Merge branch 'main' into 3dtexturing-fix-seam-bleeding-non-manifold

Jeroen Bakker reviewed 2023-03-01 10:52:37 +01:00

source/blender/blenkernel/BKE_pbvh_pixels.hh

						
				@ -248,0 +261,4 @@

				/** \name Fix non-manifold edge bleeding.

				 * \{ */

				// TODO: move to image wrappers?

Jeroen Bakker commented

2023-03-01 10:52:37 +01:00

These TODO's should be fixed or removed.

Jeroen-Bakker marked this conversation as resolved

Hans Goudey changed title from ~~Texture Painting: Fix Seam Bleeding of Non-Manifold Sections of Mesh.~~ to Texture Painting: Fix Seam Bleeding of Non-Manifold Sections of Mesh

2023-03-01 18:05:54 +01:00

Jeroen Bakker added 2 commits 2023-03-09 15:39:59 +01:00

126db404c2 Merge branch 'main' into 3dtexturing-fix-seam-bleeding-non-manifold

2dd113ca0d Moved ImageBufferAccessor to image wrappers.

Jeroen Bakker added 1 commit 2023-03-09 15:42:42 +01:00

49875a33a4 Remove debug code.

Jeroen Bakker added 1 commit 2023-03-09 15:47:20 +01:00

5f0ce39141 Update license header.

Jeroen Bakker referenced this issue from a commit

2023-03-09 16:11:14 +01:00

Texture Painting: Fix Seam Bleeding of Non-Manifold Sections of Mesh

Jeroen Bakker merged commit b0037c5c6b into main