Runtime increases when a subset of the point cloud are co-planar points

[Sheradil]

Hello,

a while ago I used Open3D for a problem I had. And I experienced a sharp increase in runtime at a specific point. I found the "reason" for this behaviour and opened an issue on their github. One of the contributors did some research and realized that it is a problem within the qhull library that Open3D uses. Here is the link to the detailed description: https://github.com/isl-org/Open3D/issues/6482

I will write a short description: When trying to compute the convex hull of a point cloud the runtime is fast as expected. However when a (large enough) set of co-planar points is added to the point cloud, the runtime suddenly increases by a factor of ~50. Within the Open3D issue I added source code to reproduce the error. But Open3D is required.

Maybe you can locate the error based on this issue without the need for further code. Or maybe it's a side case that is not worth to fix (or I did something unintended).