I am creating this thread to post all the reasons Ray Tracing is broken in 4.23. I’ve already reported quite a few of them in the bug submission form, but I doubt all of the fixes will get the priority, so hopefully creating some waves here on the forum will pull some string.
Let’s start with impossibility to create proper image based lighting in 4.23:
Skylight has 3 mobility modes: Static, Stationary and Movable. All produce very different results with Ray Traced skylight enabled. Up until 4.23 Preview 7, Static mode worked and was only mode that produced correct results. Since Preview 8, Static mode no longer works, and both Stationary and Movable modes produce extremely wrong results.
First, let’s render ourselves a path traced reference, which looks more or less correct:
Now, this is ray traced skylight in Static mode. This mode has worked up until Preview 7 and produced relatively similar results. In Preview 8 it now no longer works anymore:
This poses many issues:
- Skylight mobility should never ever affect shading when ray traced skylight is enabled
- Any rasterized reflection/diffuse convolution effects should not be mixed with raytraced skylight.
- Most of the game engine users/developers don’t have nearly enough experience with offline rendering to know if they are getting the right result or not. Due to this reason, it’s all the more dangerous that they are getting severely inaccurate results out of the box.
EDIT: So apparently Static Skylight mode still works with Ray Tracing in 4.23 P8 but under a random circumstances I am unable to reproduce. This is a result with Static Skylight and enabled GI: