I welcome all you UE developers!
I’d like to start a thread about the need for Velocity Pass and Output Velocity options in UE5. You know, this is now always enable in UE5 and we get great quality TAA and Motion Blur with reduced ghosting effects. That’s fine and it works great in most cases. In addition, we have the Output Velocity option for translucent materials, which gives us more options for rendering such objects.
But, some time ago I encountered one rather unobvious problem, the easiest solution to which would be to disable writing to the velocity buffer. This applies to very large scale objects, with a radius of several thousand km, which move around a point in space at fairly high speeds. This situation creates a rather strange behavior in TAA and Motion Blur - we see the opposite effect of using the velocity buffer. This generates a ghosting effect on such large-scale objects with a write to the velocity buffer.
If I turn off post-processing, such as TAA and Motion Blur, this ghosting effect disappears, the object moves smoothly and evenly, as far as it can be visually noticed. I can assume that this is due to certain calculations errors at these scales and it would be almost impossible to overcome, even using double-precision calculations as I do, there are still possible errors.
To be more accurate, I made a short demo video:
A great option for solving this would be the ability to disable writing to the velocity buffer for such an object. I did this using translucent material and it got rid of the ghosting effect with the Output Velocity option turned off. And it brought the effect back again if the option is on. But unfortunately, this option, for some reason, is not available for opaque materials, although it would be very helpful in these situations.
I spent several weeks trying to find a solution for this. But still no success. Maybe there are other ways I don’t know about. Maybe some of you know?
Also, I’d like to know why we don’t have the option to disable Output Velocity for opaque materials, as is done for translucent materials? Is there some reason for this? I think such an opportunity would be very useful in situations like mine.