The following describes known limitations related to painting in Mudbox.
Paint does not bleed correctly when UV shells share coincident edges
The automatic edge bleed feature may not work as expected while painting whenever UV shells have been laid out to share identical edges or lie exactly on top of each other to optimize texture space.
Workaround: The edge bleed feature is currently designed to work optimally when UV shells are separated. If possible, sew any coincident UV edges to reduce areas where the automatic edge bleed might fail or ensure UV shells have a small distance of separation. Otherwise, if UV shells must be laid out in a coincident fashion, some touch-up to the 2D texture image may be required.
UV smoothing produces unexpected results on tri-based models
The UV smoothing options for the Add New Subdivision Level and Extract Texture Maps features do not produce expected results on models with three-sided polygon topologies.
Workaround: Smooth the mesh and UVs on a tri-based model prior to importing to Mudbox.
Saving file when unpainted UV tiles exist outside of camera view causes those tiles to be not paintable
Painting and subsequently saving a scene file containing multiple UV tiles, and some unpainted UV tiles exist outside of the camera’s current view when the file is saved, causes those tiles to appear black and not paintable when the file is subsequently re-opened. That is, texture files for the unpainted UV tiles are not saved with the scene.
Workaround: Ensure when painting a file with multiple UV tiles that the file is saved early on with all objects visible to the camera’s view with some tiles initially painted.
Workaround: When a scene has not been saved as previously described, and the texture maps for some UV tiles are missing, re-create the texture maps as follows:
Re-import from PSD fails to project onto empty paint layers
The Re-import from PSD feature fails to project paint if the active paint layer is empty
Re-import from PSD projects incorrectly on models when using ATI graphics cards
Re-imported textures may not project correctly on models in Mudbox when re-imported from Photoshop on computers using ATI graphics cards. Textures may exhibit large unpainted regions on interior faces after projection
Workaround: Subdivide the model once or twice (if this has not yet occurred) prior to re-importing, or step up to a higher subdivision level.
Re-import from PSD fails to project unless one object is active
The Re-import from PSD feature fails to project unless at least one object is active in the 3D View.
Workaround: Click on any object in the 3D View prior to using the Re-import from PSD feature.
Blur brush and Clone tool limitations
Visible paint layers affect the blurring effect on a selected layer and may not provide desired results. Blend modes other than "normal" also produce undesirable results on visible paint layers when blurring.
Workaround: The layer you wish to affect should be the only one visible, and it should be set to the Normal blend mode. If multiple layers need to be blurred or cloned, merge them prior to using the tools and ensure you turn the visibility off on any paint layers you do not want affected when blurring.
The Blur and Clone tools do not currently work as expected whenever a stencil is turned on in the 3D View.
The Blur brush does not currently work when the Mirror property is turned on.