The image below show the model created by MarkupsToModel. Some points get ignored if others create a concave trajectory. The final model has always a convex surface. I suppose it’s the intended algorithm in use.

I wish to know if the final model can strictly be bounded by the points, creating concave surfaces too. I suppose it should be done deep in the C++ code if it’s feasible. That’s beyond my means. Please see it as a note for a further enhancement of this module.

It is impossible to have a smooth surface and go through an arbitrary set of points, but you can get close by enabling alpha shapes algorithm. To do that, disable “Force convex output” and find a “Convexity” value that works well for your point set. See more information in the module documentation.

Thanks for the reply. It would have been useful to be able to freely create a segment following anatomic boundaries. This would have been time consuming too, but at least, repeatable and precise.

All the tools in Segment Editor do exactly that. For example instead of dropping markup points paint small seeds and create a complete segmentation using “Grow from seeds” effect. It supports arbitrary shapes, can segment any number of structures at once, and it even takes the underlying image into account.

Markups to model module is a geometric modeling tool and it is not meant to be able to represent arbitrary shapes.