Motion Blur behaves weird with camera relative actors (actors that rotate and/or move with the camera) in 4.11 and this behavior continues in 4.12. It looks like what could basically be described as a failed attempt at correcting the motion of a non-moving object.
Steps to Reproduce:
In addition to this, Motion Blur creates a black shadow at the edges of the screen. This happens in viewports only.
Motion Blur in general seems to be broken for anything that is dependent on high motion scenes.
Hi Xaymar,
After going through our logs it seems that motion blur is kind of unstable at the moment. There are several issues logged (most sequencer related) I found this one that seems similar: Unreal Engine Issues and Bug Tracker (UE-27455)
The dark shadow is a bug that hasn’t been addressed yet and I have logged a bug report here: Unreal Engine Issues and Bug Tracker (UE-34678)
Thank you for submitting a report!
I realize you can’t see the screenshots but I am confident that motion blur is definitely being looked at and will be addressed in a future release since there are so many issues with it currently.
I don’t think what I am experiencing is the same as the first one you linked. Texture detail is fine for me, but there is a ghosting/artifacting effect with moving objects which disappears if you disable Motion Blur.
It seems that for whatever reason the objects that aren’t supposed to have motion blur receive it anyway (object motion and camera motion are equal, so it theory we have a perfect focus, no blurring happens to it). It could be solved by testing depth and motion for the associated motion texel, but that would add a bit of overhead to it. Example (Pseudo-GLSL):
vec3 color = texel(curX, curY).rgb;
vec3 currentTexelColor = color;
... (in loop)
halfp float weight = clamp(dot(targetTexelMotion, currentTexelMotion), 0, 1);
color += (targetTexelColor * weight) + (currentTexelColor * (1.0 - weight);
This will not produce realistic results, but will prevent motion blur from creating halos for objects that have none or less than the current motion. Clamping could be skipped if the motion vectors are normalized to the same range first.
Hi Xaymar,
The steps to reproduce can be pretty misleading. If you look at the description it states that the visual artifacts are related to the motion blur and not the texture.
Motion blur is currently being worked on since there are a lot of issues with it at the moment. I will go ahead and log another report on this specific case to increase awareness of how important the issue is. You can find the report here:
I’ve included the info you provided in a private comment to the devs to increase visibility. I was unable to repro this issue on 4.11.2 during my investigation so this issue has been labeled as a regression.
Hi I’m also experiencing this one. Noticeable artifacts are showing in my character. This happens when I try to spike up my motion blur value to 1. This is in version 4.14.3
Hi AlsonEntuna,
Currently we don’t think the artifacts are severe enough to devote development time to polish. During testing they seemed very minor and you would have to have very extreme settings to make them occur.
If you do want to bring more attention to this I would recommend voting on the issue. We look at the top voted issues in our public JIRA to gauge where the communities interests are.
!
Hey Ed Burgress,
I’m not sure if you are aware of the fact that the reproduction steps I provided aren’t the only case where this happens. The effect is insanely visible when the movement of an object nears 0, either due to distance or due to having the same speed as the camera.
This is only one of three rendering issues I’ve encountered. Second one is Bloom not behaving as expected when the object is on the edge of the screen/viewport. Third one is with the smaller Lens Flares which do not fade out like the larger ones do.
Unfortunately, even while testing under various conditions and speeds the issue wasn’t prevalent enough at low “per object size” values. I had a discussion with the developers and a fix for this currently isn’t on the roadmap.
That’s why I recommended voting on the issue because the settings/situations used to reproduce these artifacts in an obvious way are considered “unreasonable or extreme”. A high vote count shows that a lot of people disagree with this decision and are getting problems with motion blur.
If the community shows more interest in the quality of motion blur and it’s issues things like this are more likely to be addressed.
Sadly, other than log the bug and argue a case there isn’t much else I can do to overturn a developer decision.
Regarding the other issues you mentioned, if you haven’t already, please make another Answer Hub post so we can address those problems individually.
While this article mostly relates to feature requests it still applies to issues that we simply don’t have the manpower to address at this time.
https://headcrash.industries/stories/why-your-idea-might-not-make-it-into-ue4/
Hi Ed,
Just arrived here when searching for this problem - I’m experiencing the same issues. Wondering what the process to vote for improvements is?
Cheers,
Kim
Hello Ed,
I see that the ticket has been flagged as “Won’t Fix”. Does that mean that Motion Blur is intended to be completely broken? Any kind of fast motion with objects or characters where the camera also moves creates this and it looks horrible.
Right now the only option i have is to implement my own post processing stack as the one in Unreal Engine is ridiculously broken beyond repair.
Hi there,
I’m experiencing the same problem!
To repruduce its enough to
take a default cube and
make it move in “Tick” e.g. DeltaSeconds * 500 in x-direction
If you place the character standing on the moving box
and look at the box in the correct angel, you will see the same artefacts.
(Look at the box, so only the edge of the box is visible on screen, works well to see them).
I really hope to get a solution for this! The only solution right now is, to turn of Motion Blur…