I’m trying to measure the surface areas of segmented muscle attachment sites using the Closed Curve (CC) Markups tool. However, whenever I trace too complex or too inwardly bending of a shape, its area automatically changes to zero. I show this happening in real-time in the attached video. I know it’s not too small an area, and in the video you’ll see on the right a smaller but simpler CC that has a non-zero area.
This issue persists regardless of which Curve Type I select for the CC and regardless of how many decimal points of precision I allow for the area.
Why does this happen? Is there any way to get around this issue?
Computing surface area enclosed by a closed planar curve is a well-defined, trivial task. However, if the curve is non-planar then the the task becomes very complex or impossible to solve. Slicer computes a soap-bubble-like-surface by warping a disk by a thin-plate spline. If the soap bubble surface is infeasible because to the shape of the curve is highly non-planar and not smooth then you will get 0 surface area.
There are many ways to define surfaces in Slicer, you just need to find the appropriate modeling tool for the task.
I suspect that you actually want to cut out a surface patch from a segmented structure. You can do that by exporting the segmentation to a model node and then use tools in the Dynamic Modeler module.
If you have trouble using the Dynamic Modeler module or you think it is not the right tool then please write a bit more details about what you need and post a couple of screenshots.
If calculating a non-planar curve’s area is infeasible, I would be happy to cut out a surface patch from the segmented mesh instead.
Unfortunately, so far I haven’t been able to do this. When I try to “Select by points” within the Dynamic Modeler module, and click Apply, my model disappears (see screenshots attached).
Is there any chance you would be open to Zooming about this issue to go over how to proceed with the Dynamic Modeler option?
If so, I would email you a Zoom link and happily Venmo you a coffee!
