Visual Artifact

[any_user]

I'm using the effect for a racing game (http://krautscape.net/), and I noticed an artifact, visible behind the wheels.




The car is a compound object consisting of a main body (Skinned mesh), four suspension parts (skinned mesh), and four wheels (static mesh)). All the renderers have an AmplifyMotionObject script. All the parts move slightly differently every frame, depending on physics.

I'm not sure what could cause the problem. The wheels causing the problem use a bumped specular shader. The first screenshot is with shadows/SSAO, but it also happens without (second screenshot). The artifact is only visible when driving on the track, but not when in the air.

Any hints what I could try to fix this?

[Diogo Teixeira]

Hi

Thank you for reporting this issue.

How did you set up Amplify Motion? Are you excluding the car from the blur using Amplify Motion culling mask?

Since you have two objects at very different speeds, to avoid sampling artifacts it's recommended that the car is either excluded using culling mask (no motion blur on car) OR rendered on top using an Overlay camera (still gets motion blur).

Please let me know if this helps.

[any_user]

Is adding the AmplifyMotionObject script to the option the same like excluding it from the culling mask, or does it work differently? If it's different, I'll try that.

[Diogo Teixeira]

Is adding the AmplifyMotionObject script to the option the same like excluding it from the culling mask, or does it work differently? If it's different, I'll try that.

In all cases, you should add an AmplifyMotionObject script to the car.

To exclude it from having blur using the culling mask: set it to a different layer as everything else and exclude that layer from the Amplify Motion Effect culling mask property.

The second option, which preserves blur on the car but doesn't mix both, involves using an Overlay Camera:
- Exclude the car from the main camera's culling mask.
- Create a second "overlay" camera that renders only the car; disable clear and attach to main camera.
- Add camera to Overlay Cameras property in Amplify Motion Effect

[any_user]

I checked it and noticed that I already had it (the car, wheels, etc.) on an excluded layer like you suggested.

It looks like it has something to do with moving objects which are close to static objects. I made a video to illustrate the problem (download it here: http://krautscape.net/download/motionblur.mov). On the left is a cube with the AmplifyMotionObject script, on the layer which is excluded by the effect (same like the car and the wheels etc.). The closer the cube is to the ground, the better you can see the artifact.

[Diogo Teixeira]

One final question:

Are the car objects being instantiated at runtime? And if so, does this also happen if you start the scene with the objects already instantiated?

[Diogo Teixeira]

I've got a new build that fixes the nullref and attempts to debug this issue. Would you mind testing it?

However, this is a public forum so I can't share the build here. Unless you're OK with a watermarked version.

If you're already a customer, please get in touch and include your Asset Store invoice number so we validate your purchase. This way we can end you full test builds directly, and we'll add you to the system so you can access official releases and devbuilds through our website.

Please let me know if there's any chance of me debugging your project. I'm available to sign any NDAs required, if necessary, in order to protect your IP.

[any_user]

Hey Diogo

Finally had the time to check if it also happens when the objects are not instantiated during runtime: It looks exactly the same. Disabling the rotation of the wheels also doesn't change anything with or without excluded layers. It also makes no difference when I don't exclude the layer of the car (with disabled rotation of the wheels).

I've also seen that on some computers the car is blurred (when on excluded layer). It normally doesn't happen on my computer (OSX), but sometimes it does. I haven't found a way to reproduce it yet. The car is a physical object that has interpolation enabled, the camera moves in LateUpdate, after default time (in script execution order), if that matters. Maybe it has something to do with script execution order?

I'll send you a mail to [email protected] with my invoice number.