Blank-Lines in vtkFixedPointVolumeRayCastMapper Renderings
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
When rendering Volume-Render images with the FixedPoint mapper and the Image is aligned to the viewing direction, planes parallel to the viewing vector exhibit black lines. however, the lines only obscure the distant part of the volume, as if the rays terminate early.
This is caused by accuracy problems in the "numSteps" computation in ComputeRayInfo. When dir approaches 0, but is not exactly equal to zero, that numSteps number is incorrectly computed significantly shorter (30-50%) than it should be, causing the rays to terminate midway through the volume.
The attached patch recomputes the ray direction after the number of steps has been calculated to ensure the ray will fully traverse the volume.