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Hello.
I've taken a look at the provided scene and I think the problem is in the number of motion blur samples. Note that it's a setting for number of samples, not number of intervals. If you set N samples, the shutter open duration is divided into N-1 equal intervals. With 8 motion blur samples you get 7 sub-frame intervals, which coupled with the 2-frame duration result in sub-frame intervals of 2/7ths of a frame. The bigger issue is that with that setup the samples for one frame do not line up with the samples for the next, and we end up not exporting all samples for every frame. Because of that when a frame needs samples from the past it ends up interpolating between the samples of the previous frame, which for your case causes the camera and rocket to get out of sync and the rocket to be blurred with respect to the camera.
If I set the number of motion samples to 9 (i.e. 8 intervals, each of 2/8ths=0.25 frames duration), the problem disappears for me. As a general rule, if your shutter open duration is longer than one frame, i.e. subsequent frames overlap, you probably want to set an odd number of motion samples to make everything line up correctly, i.e. you want shutter open and close to match up with motion samples from the previous and next frames.
As another workaround you can disable animation and render individual frames. In this case there is no reuse of motion blur samples from one frame to the next.
I suspect jasonazure's problem is due to the same issue.
All that said, this is definitely also an issue on our end for not handling the setting properly.
Hope this helps.
I've taken a look at the provided scene and I think the problem is in the number of motion blur samples. Note that it's a setting for number of samples, not number of intervals. If you set N samples, the shutter open duration is divided into N-1 equal intervals. With 8 motion blur samples you get 7 sub-frame intervals, which coupled with the 2-frame duration result in sub-frame intervals of 2/7ths of a frame. The bigger issue is that with that setup the samples for one frame do not line up with the samples for the next, and we end up not exporting all samples for every frame. Because of that when a frame needs samples from the past it ends up interpolating between the samples of the previous frame, which for your case causes the camera and rocket to get out of sync and the rocket to be blurred with respect to the camera.
If I set the number of motion samples to 9 (i.e. 8 intervals, each of 2/8ths=0.25 frames duration), the problem disappears for me. As a general rule, if your shutter open duration is longer than one frame, i.e. subsequent frames overlap, you probably want to set an odd number of motion samples to make everything line up correctly, i.e. you want shutter open and close to match up with motion samples from the previous and next frames.
As another workaround you can disable animation and render individual frames. In this case there is no reuse of motion blur samples from one frame to the next.
I suspect jasonazure's problem is due to the same issue.
All that said, this is definitely also an issue on our end for not handling the setting properly.
Hope this helps.
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