We believe expanding the fisheye camera functionality should be approached as a feature request. Our approach would be to add an input port on the Make Spherical Camera node to allow switching between rendering as circular fisheye and equirectangular (or eventually other formats like cubemap or HEALPix). We think the already proposed FR, Render scenes to equirectangular panoramas and cube maps could be expanded to include this enhanced circular fisheye functionality.
Alternately, if you know of some other approach to implementing support for angles > 180º that would be about equally efficient as the current Make Fisheye Camera, please let us know.
We are labeling this “not a bug.”
Isn’t the equirectangular solution already also going to be a 6 camera pass? Or a different method?
Yes, either image-based method (6 cameras to equirectangular or 6 cameras to circular fisheye) will have roughly the same performance.
So a triangle that occupies a reasonable amount of the FOV the resulting fisheye is incorrect.
This is consistent with what we mentioned in the Make Fisheye Camera node documentation. You can work around that limitation by starting with a finer mesh (more rows/columns on Make Sphere/Square/Tube/Cone/Torus/Gridlines/Supershape/Parametric; more subdivisions in Make Icosphere; using Spike 3D Object as a tessellator).