Motion or Ghost Trails: How to.

[Aldaryn]

Hi there!

This effect is called motion blur, and it happens, because the motion is quicker than the camera shutter, so more segments (Its a bad thing to call it that, but heck...) of the motion are captured on a single frame. This produses the motion blur effect. (Sometimes it's the camera that is moving, but this matters only little, relatively, the scene is moving not the camera... :) )

There are some ways to fake this effect in MAX, I'll try to go over each of them:

First, there is a realistic method: Create a camera, and turn on Motion Blur in the Camera's settings, under Multi-Pass Effects, thre are several controls to adjust the effect, the most important is the Total passes setting, this will adjust the quality, and the required time to calculate. This method renders sub-frame frames, for each frame it will render more, determined by the lenght of the exposure. This way is a quic and nice way to simulate motion blur, but it will multiply the overall rendertime by the Total passes amount. And that is bad. However, this is the only true 3D motion blur available in MAX...

The second, and third way can be accessed through the Objects properties dialoge, you can bring this out by right clicking on an object, and selecting properties. In the dialoge box, there is a box called: Motion Blur.
The separate ways: Object: The blur will be calculated for the selected object. Image: Whole image will be blurred. The first option is better, when you're working with a specific blurred object, the second is good when the camera moves, and you don't want to fu*k around with hunderds of objects... :)
The method is simle: Every object will get a motion vector, and with some filtering, the rendered objects will be blurred along their motion vector. (It's a bit complicated than that... yeah)The advantage: quick... Disadvantage: Not accurate, with spinning objects you can get REALLY wierd results....

And the last way to do it without 3rd party plugins: Apply a Material to your particle system with a Particle Motion Blur (Particle MBlur) map in the materials opacity (transp. etc...) slot. This will generate an opacity map to the particle by it's motion vector.
This method works only with particles, and it has been around MAX since 1.0, I think. This method is quite fast, but inaccurate, hovever, this would suite your needs too, if you want to recreate the effect on your picture.

Wow, I'm getting pretty tired by all this typing. So I'll quit.

Good luck.

- A.

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