Is it possible to have halos appear behind a raytraced transparent object?

I can’t seem to figure out how to get halos behind a raytraced transparent plane to appear. It works fine with ztransparency, but I need it to be raytraced for the IOR value. Hopefully someone knows of a workaround for this, or a better alternative to using halos.

For an object to be “seen” through a RayTrans material, it must be “Traceable,” one of the Material Options. Some Materials or material options are not Traceable by default and cannot be made so – I think halos are one. Strand Render for hair particles is another.

If you must have a halo-type look, you may have to resort to mesh particles and create a sprite-like planar object with alpha masking to give the soft look. This kind of material can be made Traceable and so should be properly seen through your RayTrans/IOR object. With true sprites, the planes can be set to always face the camera so there are no planes seen edge on or at an angle. Not sure if you can do this with mesh particles. The plane designated as the particle mesh can be made to Track To the camera with a constraint, but I don’t know if all its particle instances will also.

If this is too complicated, you might be able to fake the effect using the Compositor, but that isn’t much less complex, requiring pre-rendering a number of sequences and some fancy-dancy nodes trickery.

Thanks, that seems like a much better alternative to using halos (In this case). I actually checked the options quickly and particles can actually be rendered as a “Billboard”, or little planes that always face the camera (or any other object that is specified).

Yes, that’s the ticket! I had forgotten about the Billboards.