Motion Blur

[AtlJimK]

Ok this maybe a dumb q but...

Is it possible to have an object blur without a camera blur?

Thx.

[AtlJimK]

Was this really that dumb of a question?

[joconnell]

Explain - have a motion blurred object in a still? Yeah sure, just animate the object as normal and render the frame when the moving object is at the frame you want - either turn on motion blur if using a normal max camera or use the motion blur switch on the vray physicam - I presume you mean having blurred objects when the camera isnt moving?

[bernhard]

good question

Well, that was a good quesion I guess.

I also didn't really understand the motion blur with vray and 3dsmax.
usually, a real motion blur is calculating 3 or 4 times the same image, and until that, it merges the different layers to one image.

so, you will get the motion blur from the object.

Hmm, but in vray and max I couldn't find something similar.

So, would be really great to know if someone can us help here out

thank you for every little help,
bernhard

[AtlJimK]

I have both objects and a camera moving in a scene but only want the mBlur on the objects and not the overall image caused by the camera movement. Thx.

[Dynedain]

Motion blur in reality is caused by the relative motion between the camera and objects.

If one object is moving faster with respect to the camera than another, that object will get more motion blur.

VRay's motion blur, since it is a full 3D motion blur, simulates this accurately.

The process you described, where a frame is rendered more than once and then analyzed is used for 2D motion blur, and isn't how VRay works.

I think if you want to have an object have mblur only affect a limited number of objects in your scene, then you will need to render two passes, with and without mblur, and then composite them togethor.

[joconnell]

You can use the motion blur render effect and then use the regular max right click properties to enable image motion blur on the objects that you want the blur effect on.

[AtlJimK]

You can use the motion blur render effect and then use the regular max right click properties to enable image motion blur on the objects that you want the blur effect on.

Tried that too....does not work. The render effect blurs the image even if The objects are set to "Object". Ionly want the rotor blades to be blurred. See below>

[joconnell]

Ah okay - if you don't get close to the blades then render a still from above, radial blur it in photoshop and use that as a texture map on a plane rotating slowly.

[AtlJimK]

Yeah, but...

Opacity maps, already animated scene etc...

It should be a simple task, but as max goes it's not

[dimo]

Hi,

you can set the mblur duration to a really small value. Then speed up the rotorblades a lot. This way you will only get visible motionblur on the blades.

Best regards,

Dieter

[Morbid Angel]

how about to render rotor blades as a separate pass, whats wrong with that?

[Shimakaze]

Dimo's suggestion is the best I suppose. You should change the motion blur settings until you're happy with the blurring of the entire picture first (even just a little blur can look good, but just experiment until you're happy) and then increase the speed of the rotor blades until they get blurry enough. You will be able to render it faster if you render out the rotor blades as a separate pass though since the motion blur only has to be calculated for those objects.
A less accurate way to go would be to render out an alpha matte for just the rotors and use that in post to apply a blur effect. That's easy to do with render elements. Or if you use a good enough compositing software you could even use the VRayVelocity render element.
I other words there are lots of options. of course if it's for a still image then you can just keep the camera stationary and off you go :P

[joconnell]

yeah indeed - I did a test shot a while back and had the rotors rotating over 10,000 degrees a second to get the right look - lots of subsamples

Vector blur is a one way 2d smudge - you'll never get a nice arc with it unfortunately.

[AtlJimK]

Thx for help.... Dimo's the man. It works to certain degree under my time frame. I wish Dimo's Multimatte worked for my RC4 and I had an updated PSD Manager then I would be in heaven