I have a scene where there`s a pipe breaking in the middle, after breaking it shakes like a trampolim, so far so good.

The thing is when I render it the motion blur renders all crazy with some spikes appearing em some frames.

Anyone know what could be the cause of this?

Not sure what it might be. Could you show a render?

Hard to tell without a sample render but I'd guess that the point count is changing in your scene.

If you are rendering with deformation blur, check for changing point counts.
If you are rendering with velocity blur, make sure that the ‘v’ attribute is doing what you expect it to in the given frame.

G

I think you might be right about the points changing.

In fact my points counts change because I use a switch node to change the whole pipe to the broken one.

But how to solve this? Is there a way for me to keep my switch and correct the motion blur as well?

I am posting my render to show the anomaly that I am having. You can see the problem better on the alpha.

It´s a Mill that I am breaking, I did some parts of the ring to fall with DOPS that is doing motion blur fine, the problem is with my broken pipes, since my brake animation doesn't generate the ‘v’ attribute by itself I tried to use the trail node with the compute velocity turned on.

Maybe there's a better way to generate the ‘v’ attribute.

About the motion Blur, how to setup the velocity blur and the deforming blur? What´s the difference?

When you compute velocity with the Trail SOP, don't forget to enable it on your object.
Object parameters -> Render -> Sampling -> ‘Geometry Velocity Blur’

Yes. I did that

It was the only that I found to reproduce some motion blur on the pipes.

Any more ideas about how can I solve this problem?

You could try using the trail sop.

I did use the trail SOP.

But for some reason it still giving me this problem

Hi ,
would it be possible to post up a basic scene file showing how your scene is working ?. ie the break up and how you are processing the geometry for motion blur ?.

r

Yes I can.

I separated just the problem the pipes, you can see in the render that the motion blur is not right when the pipes break.

There isn't any dynamics on this file, just CHOP animations.

I did try to rename all the labels for English for better understanding, sorry if I missed some.

Hi,
The motion blur is correct. The problem lies in the fact your geometry is moving large distances over single frames

ie frame 36 pipe breaks , frame 37 its moved over 4 meters ! Thats the equivalent speed of an electric nervous pulse !. Frame 38 moves back to start position 4 meters , frame 39 moves again 4 meters. Rendering that will give you one big blur !



r

Thanks for the help.

What I think that´s strange is that even the piece of pipe that is not moving like the little piece in the middle top is receiving a weird motionb blur like a spike upwards, the motion blur should be given in a direction that the object is moving, the result that I am seeing is a spike of motion blur upwards, not in the direction that the pipe is moving or no moiton blur at all in the case of the pipe that is not vibrating. It´s like is bleeding to the wrong direction.

Agree?

Anyway thanks again for the help.

I'll have to respectfully disagree with the previous assessment.

The motion blur is definitely off. try moving the trail sop INTO each branch – before your switch sops (the ones that switch between the broken branch, and the whole one).

What's happening in your shot is when you replace the whole geometry with the broken pieces, the point count changes… this makes things nasty for trail sop. It hates changing point counts.

G

Thanks for the feedback.

I´ll try to do that than I´ll post here the results.

Thanks again everyone for the help.

Yeah!!! It worked!


I did what you told me keyframe and it totally worked, You can see by the motion blur at the same frame as before the difference.

Again thank you very much for the help guys It really helped.

If somene got more tips for the motion blur be wellcome to share.

See ya.