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Manifoldness or Watertightness:
Manifold meshes are characterized by strong connectivity. In simple words, each triangle of a mesh should be connected to exactly three neighbor triangles.
Strong connectivity guarantees that none of the following problems occurs:Holes
Redundant triangles
Merged objects
Correct triangle orientation:
Meshes with correct triangle orientation uniquely define the inside and the outside of the object. If this requirement is not met, printers may not be able to correctly distinguish between printing volume and empty space. Triangles with incorrect orientation (in black) may also be visualized incorrectly by CAD programs.
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Absence of intersections:
For a high quality printout, the volume of each object needs to be uniquely defined, but self intersecting objects may define the same volume multiple times .
Although many printers accept files with self intersections, the surface quality of the final printout may be negatively impacted. Additionally, computing the volume and surface area of such meshes for further printability analysis yields incorrect results.
Improvements in version 22.0.x
Higher success rate: Up to 33% higher optimization success rate on heavily broken 3D models.
Smart false positive detection: In the old algorithm some files were considered repaired although significant parts of the model were removed. The new algorithm is 14 times more accurate in detecting and handling such cases.
Faster printable files recognition: The new algorithm is up to 50% faster for large files, avoiding unnecessary optimizations on already printable models.
Better quality: Internal triangles are being removed more carefully and consistently now, improving print quality. Self-intersections are resolved by triangle splitting instead of triangle removal, providing a more accurate result.
Better hardware utilization: Switching to a higher resource package will now reduce the processing time of individual file uploads even more than before thanks to 45% better hardware utilization.
A rough diagram on the new algorithm can be found here. The new algorithm reuses the hole filling logic from the old one and adds an Outer Hull concept which is based on this and this paper.
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Disabling mesh optimization
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