Is there an easy way to draw an ellipse shape in a 3D plot? I want to find the points located within the ROI and I notice inROI has an x,y,z option which is great but it seems to be only possible using cuboid ROIs in 3D.
As you said, to get a 3-D ROI, only the Cuboidal shape is supported using drawcuboid. You can get an ellipse shape using drawellipse, but this 2D and you can specify the axes. Here's an overview of all the objects that represent ROIs of various shapes: ROI Creation Overview