I’ve decided to make a model of a lancaster bomber. It is not yet complete, and I have not done texturing, but here it is so far… any C&C would be appreciated.
Although nobody has yet replied, I will post the following problem. (I suppose it is technically a composition/rendering problem, but it is also part of this project.
-I am trying to vector blur only the propellors. But I run into this problem…
You best bet here is to render the plane in one pass/layer and the spinning propellers on another pass/layer and then composite the two together.
Something else maybe parenting the props to the plane, then key their rotation and use the cyclic extrapulation in the IPO curve editor to continue the spinnning.
And here is another trick: Create a cricle and create an animated texture map that emulates spinning props and use that. That’s something we used once in Lightwave. Cut down on the animation rendering time.
I was like you, spent a couple hours trying to get the propellor to spin on a P-40 in lightwave when one of the older guys said, “Hey just do this, they’ll never know if the action is focused on the bullets and fireing and stuff.” The illusion worked.
I’d like to critique further, it’s a nice piece, but it will have to wait until tomorrow.
-I am trying to vector blur only the propellors. But I run into this problem…
If only the propellors are moving, then only they will be blurred. If the concern is rendertimes, then render with alpha, have the background transparent so it doesn’t cover the plane.
You will still have the problem of the front of the plane not covering the propellors. Either you play around with the Z buffer (lots of hassle) or do vector blur on the entire scene.
Ian
Thanx for the replies.
IanC: The only problem is with vector blurring the whole scene is that to blur the props enough, the blur setting will be way to high, thus blurring everything way too much.:eek:
Unimatrix: The only thing I don’t understand is how to composite the props and the plane together so that they aren’t overlapping incorrectly. 
IanC: The only problem is with vector blurring the whole scene is that to blur the props enough, the blur setting will be way to high, thus blurring everything way too much
If the plane isn’t moving, then the vectors will be 0, and thus those bits won’t be blurred. You can also specify a minimum movement to be blurred.
That’s true, but I do plan on making the plane move in an animation.
No time to explain theory about how to do this (vector blur props only)now. Will post tomorrow.
Setting the minimum movement will work 
The movement is based on relative movement between the camera and the object, so it is set in pixels. This should work fine.
OK… i will try that. Haven’t really gotten to know the nodes system yet;) .
Well. The minimum speed works fine, but if i wanted more control, theoretically would the following work?
- In a separate layer, duplicate the plane. Change everything but the props to a shadeless bright green material.
- In the first layer, keep the plane with the original materials.
- Use the special version of blender (By Bob Holcolmb) to combine both images, but the plane would fill only the green area (the duplicated shadeless plane.
- The props and plane now overlap correctly! And the blur of the props can be controlled seperately.
I hope I explained that well enough. I don’t see any reason why it shouldn’t work, but if anybody can think of one, feel free to let me know.
Now, all I have to do is test it!