Motion Blur Settings Confusion

[hdace]

I'm confused about Motion Blur Settings. I've got a space scene with an astronaut walking slowly on a ship's hull. Meteorites suddenly zoom past. The meteorites are "-xxx" type instances. I've got instance MB turned on with 6 steps but nothing happens. Then I turn on Objects MB with 6 steps and suddenly blur works fine. I didn't want to turn on Objects MB because there are other objects in the scene that I don't want to have any MB. Only the meteorites. Now all of them are blurring. Why can't I separate the blur between instances and objects?

[juanjgon]

Are you sure? ... I am testing the instancing MB with the objects motion blur disabled and it seems to work fine.

If you want to send me a sample scene with this problem I could test it here to try to find the source of the MB issue.

-Juanjo

[hdace]

I can't send anything at this time, sorry. I notice from your image that you've got Camera & Lights turned on. I don't understand these settings either. Does having Camera turned on mean that everything will have motion blur? Because in I have it turned off. And I have lights turned off. I only want the instances to have motion blur.

[juanjgon]

The camera motion blur must be enabled if you want to render the motion blur effects due to the camera transformations. The same happens for the lights, it must be enabled if you want motion blur effects in the Octane lights transformations.

So in theory you should be able to render the instances motion blur without get motion blur in the camera, lights or other objects, as you can see in the attached sample image. Your problem can be a side effect of something else related to your scene, but it is hard to figure what could be the problem without a scene to reproduce it here.

-Juanjo

[hdace]

Oh I see now. It's all about the addition of transformations of different things. Makes sense. In my case I would still have preferred to have only the instances turned on, but we'll figure it out some other time... Maybe the Octane -xxx null method of instancing considers the nulls to be objects with no instances.

[juanjgon]

Oh I see now. It's all about the addition of transformations of different things. Makes sense. In my case I would still have preferred to have only the instances turned on, but we'll figure it out some other time... Maybe the Octane -xxx null method of instancing considers the nulls to be objects with no instances.

Ahh, yes, this is the problem. If you are instancing using nulls with the "-name" trick, these instances are loaded as objects from the motion blur point of view, so you need to enabled the objects motion blur to render the MB effects.

Perhaps you could try to instancing these objects using the native LW "Clone Instance" tool to add LW native instances over null objects. These instances over null objects should be affected by the instancing MB switch, so you could disable the objects motion blur.

-Juanjo

[hdace]

Okay, that clears it all up. Cheers!

[hdace]

Hi Juanjo.

Unfortunately I'm still having problems with this. Luckily I can render a different part of the scene for the time being. But I really need to get this situation fixed soon. I'm really sorry I am not able to upload anything to you so I just have to describe it.

The meteorites are supposed to fly past the camera at very high speed and I only want them to blur. I don't want anything else in the scene to blur. That's why I'm instancing them, so I can select MB instancing only. They have such low poly counts it otherwise wouldn't really be a problem for them to be clones. I thought that turning on Update Materials (Only materials in enabled obj.) had solved the problem because I finally got blur and it looked good on a single frame. But after rendering several frames I discovered that they weren't moving! I was rendering backwards from a mid-point in the "shower" so I could see lots of them at the same time from the first frame render. But then they just stayed in the same position.

They're supposed to fly in from the top of frame and crash into the spaceship near the bottom of frame. The thing that might be causing problems is that I've animated the scale of each null from 0 to 1 at the beginning of each flight across frame and after hitting the ship the scale goes from 1 back to 0 again. Isn't scale animation part of simple transformation? That doesn't count as deformation, does it?

I tried converting all of them to native LW pivot type instances, but then I couldn't get any blur at all! No matter what settings.

I could try removing the scale animation, if that is causing the problems, and try animating their Dissolve settings instead. But that's a lot of work if the scale isn't the cause of the problem. Doing too much testing means the rendering workstation has got too much downtime, but if you're not sure, that's what I'll have to do.

Thanks for any ideas... --Hal

[juanjgon]

Really it is hard to understand the problems that you have without the scene, but I can confirm the the motion blur can be enabled in the LW instances over null objects while all the MB of the other objects and the camera is disabled. Attached you have a sample scene and a screen grab ... the "ship" object (the green cube) is moving without motion blur, while the "box" object (the red cubes) are native LW instances over null objects that have MB because they are instances.

You should be able to scale from 0 to 1 in one frame the null instances without problems ... perhaps you should scale the nulls to 0,0001 to avoid problems.

Also remember that the instances motion blur is rendered only in the final F9/F10 images. The IPR doesn't support instances motion blur due a limitation in the LW SDK.

-Juanjo

[hdace]

Thanks very much for the test scene. Hopefully I'll get to it sometime this afternoon.