Box projection reflection probe gives distorted image

[bdeschryver]

Hey everyone,

I have a VR scene on Android build which uses reflection probes with box projection option.
See image of a corridor with cabinets with a mirror at the end:

I do not understand why the reflection image is distorted. Is this a bug ? How to have it flat like in real ?
Thank you

[bdeschryver]

Looks like the size of the projection box has an influence, so adjusting it cold provide better results. But I don’t understand why…

[arkano22]

@bdeschryver

Looks like the size of the projection box has an influence, so adjusting it cold provide better results. But I don’t understand why…

That’s just how box projection works. It assumes the environment is mapped onto a box, so you have to provide a size for the box. If the box and the captured environment have different sizes, then the reflected image will be weirdly distorted.

https://docs.unity3d.com/Manual/AdvancedRefProbe.html

The Box Projection option allows you to create a reflection cubemap at a finite distance from the probe, thus allowing objects to show different-sized reflections according to their distance from the cubemap’s walls. The size of the surrounding cubemap is determined by the probes zone of effect, as determined by its Box Size property. For example, with a probe that reflects the interior of a room, you should set the size to match the dimensions of the room.

[bdeschryver]

Thank you for your answer. Still complicated for me to understand what size the box should be in this case (corridor between 2 cabinets with a mirror on one side, as in the image).
I found that with half size box of that corridor space, it looks best when being in the center position.

But I am surprised by the image deformation on the cabinet lower part… Why so ?

[AcidArrow]

@bdeschryver

Thank you for your answer. Still complicated for me to understand what size the box should be in this case (corridor between 2 cabinets with a mirror on one side, as in the image).
I found that with half size box of that corridor space, it looks best when being in the center position.

But I am surprised by the image deformation on the cabinet lower part… Why so ?

Because the image is projected on a wider box than the corridor, so the wall parts of the cubemap are projected on the floor.

[c0d3_m0nk3y]

The box should match the room size. The reflections will only be correct where the walls line up with the box, so for example, reflections on the shelves would be incorrect. That’s just the limitation of the technology. And yes, usually the reflection probe should be in the middle except when something is in the way that would prevent it from seeing the entire box.