Problem summary
When creating a holdout matte, there is a difference in result between using a DeepMerge (Holdout) node and a DeepHoldout node when the footage is motion blurred. The DeepMerge (Holdout) node creates greater artifacting in the transparent areas than the DeepHoldout node.
Note: This happens for both Deep data coming out of a ScanlineRender node and when reading in pre-rendered Deep data from an external renderer.
Customer reported version
nuke.11.0v1
Nuke11.2v5
Customer reported platform
windows7
Originally fixed in
11.1v1
Steps to reproduce
1) Import Deep data through two separate 'DeepRead' nodes or using a ScanlineRender Deep setup, ensuring that there are two objects and that one object occludes the other (or open the attached .nk)
2) using a 'DeepHoldout' node connect the 'main' input to the occluded 'DeepRead'/'ScanlineRender' object and connect the 'holdout' input to the 'DeepRead'/'ScanlineRender' object that is being used to occlude.
3) using a 'DeepMerge' node, select the 'Holdout' option and connect the 'A' input to the occluded 'DeepRead'/'ScanlineRender' object and connect the 'B' input to the 'DeepRead'/'ScanlineRender' object that is being used to occlude.
4) Compare both using a Merge (difference) Result: You will see that the DeepMerge has a sufficient amount more artifacting than the DeepHoldout.
Workaround
Suggestion would be to use DeepHoldout node if possible over the DeepMerge (Holdout) node for best results when using motion blur.
Reproduced by support
This bug has been reproduced in:
Nuke 11.0v3 - Windows 7 - MacOSX 10.13 - CentOS 6.9
Nuke 11.0v1 - Windows 7 - MacOSX 10.13 - CentOS 6.9
Nuke 10.5v6 - Windows 7
Nuke 10.5v1 - Windows 7 - MacOSX 10.13 - CentOS 6.9
Nuke 10.0v6 - Windows 7
Nuke 10.0v1 - Windows 7
Nuke 9.0v9 - Windows 7 - MacOSX 10.13 - CentOS 6.9
Nuke 9.0v1 - Windows 7
Nuke 8.0v7 - Windows 7
Nuke 8.0v1 - Windows 7
This has regressed in 11.2v1 <- First version with the issue after fix
Earliest version tested Nuke 7.0v10
- Issue found in all tested versions.
Expected behaviour
Expecting there to be no difference between the DeepMerge (Holdout) and the DeepHoldout node results
Actual behaviour
Different results between DeepMerge (Holdout) and the DeepHoldout nodes, with the DeepMerge providing greater artifacting in the image.