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# Rescale reflection captures

Hi,
I’ve been working a lot with reflection captures lately, primarily box reflection captures since I do archviz and they’re suited to square or rectangluar spaces. Well, not quite. One problem I’ve discoved is that the reflections being captures get non-uniformly scaled if I use a box reflection capture that doesn’t have the same size in all directions. Would it be possible to have a feature that lets me get uniformly scaled reflections even though my reflection capture box is not uniformly scaled? I realise this may be an inefficient way to do it since you may need to sample a larger area and then crop out the stuff you don’t want, but since reflection captures aren’t dynamic, I can’t see the cost being a problem. Maybe there are other issues that would prevent this, but it would be very nice if it was possible.

Show some pictures. Never have this problem my self and we use lot of non cube reflection captures.

Here are two pictures. The first one gives a VERY distorted reflection (I did make it quite extreme on purpuse, it’s rarely this bad but it’s quite often noticeable), and the second one gives a correct reflection.

Context of those pictures would help. First picture look that you have long narrow corridor. Is that the case?

No, both pictures are the same geometry, same camera and a box reflection capture placed in the exact same spot. The only difference is that the refcap in picture one is 20x166x166 cm (non-uniform in other words) and the second is 166x166x166 (uniform scale). So I guess it’s pretty obvious that the scale makes a big difference =)

Box reflection geometry should match exactly with geometry of room. I guess your incorrect results are cause by this.
Box geometry is used for two separate things. Firstly box geometry is used to compute which pixels are affected by this capture. Secondly box is used as proxy geometry where reflections are from. This dual nature of box size is not always what user would want but I guess it’s done like that for simplicity(less parameters to tweak) and optimization.(less data to send for GPU)

Yes I know that. I’m not trying to find a bug or anything, I’m asking for a feature that would make it more consistent, albeit probably a little more expensive to render.
For a room that is just four walls it usually works ok, but if the reflections are to be correct, many rooms demand several captures to get the right reflection in the right place.
Btw, none of these captures match the room, but still the uniformly scaled one gives a correct result. So the problem here is not with the geometry, but with the fact that non-uniformly scaled box captures distort the reflection to a lesser or greater extent. I’m just asking (hoping a dev could answer) to get an option to crop instead of rescale, so to speak. That would allow me to get correct perspective on reflections regardless of the uniformity of the refcap.