Fairness criterion for `EdgeDecimator`: Keep certain triangle shape or enforce certain triangle shape

[Nevsden]

Could we add fairness criteria to the EdgeDecimator module? An idea would be to only allow removal of edges, which do not lead to degenerate triangle shapes.

https://graphics.stanford.edu/courses/cs468-10-fall/LectureSlides/08_Simplification.pdf Slide 54

[dima634]

This should be straightforward to implement. However, are you certain that you need it for IncrementalRemesher and not for EdgeDecimator? The slides discuss incremental decimation, which aligns more closely with what EdgeDecimator implements.

[Nevsden]

@dima634 You are right. This should better be implemented as a feature to the EdgeDecimator as a plug-in criterion. E.g.

    // Quality taken from 
    let quality = radius / edge_length;
    let mut decimator = EdgeDecimator::new()
        .decimation_criteria(decimation_criteria)
        .keep_boundary(true)
        .enforce_triangle_shape(quality);
    decimator.decimate(&mut mesh);

[Nevsden]

After doing some research, I came across this algorithm from the RWTH Aachen, which seems to do a good job improving mesh quality after the decimation of edges.

Would this feature be something, you would like to see in your library?

https://www.graphics.rwth-aachen.de/media/papers/slicing1.pdf

[dima634]

@dima634 You are right. This should better be implemented as a feature to the EdgeDecimator as a plug-in criterion. E.g.

    // Quality taken from 
    let quality = radius / edge_length;
    let mut decimator = EdgeDecimator::new()
        .decimation_criteria(decimation_criteria)
        .keep_boundary(true)
        .enforce_triangle_shape(quality);
    decimator.decimate(&mut mesh);

I think the easiest way to implement it is to create a new EdgeDecimationCriteria that would check triangle quality after collapse. And if it drops below a certain value ban such edge collapse.

[dima634]

After doing some research, I came across this algorithm from the RWTH Aachen, which seems to do a good job improving mesh quality after the decimation of edges.

Would this feature be something, you would like to see in your library?

https://www.graphics.rwth-aachen.de/media/papers/slicing1.pdf

I find it quite similar to what IncrementalRemesher currently offers (however sharp feature may be smoothed a bit, not sure).

[Nevsden]

You are right, it's very similar. But in one point I would contradict: the algorithm described in the paper still tries to keep the number of edges minimal.

Out of curiosity: would this minimum edges feature be something that I could already achieve with the Remesher pipeline?

[dima634]

Out of curiosity: would this minimum edges feature be something that I could already achieve with the Remesher pipeline?

I guess no, mb with a combination of remeshing + decimation.