View Full Version : 1st Time 4 Everything

04-11-2012, 10:46 PM
Hi guys! I'm doing a scene with a bunch of chariots, and I've used this same chariot before without any problems, but today's the day. I scanned the wheels so I could use the MDD plugin, and this is what happened. As you can see, the wheel changes from bigger to smaller. It does this with every frame, big, small, big, small, all the way thru the 120 frames. I only scanned 12 frames for the animation, since the cycle is really 360 deg in 6 frame, so I have 2 revolutions for the wheels. Has anyone seen this or maybe had this problem before? I really need to fix this if at all possible. thanks

04-12-2012, 01:21 AM
6 actual sample frames is not enough samples for the wheels. The MDD playback node/plugin likely only does a linear interpolation between sample frames. As such you will see shrinkage (and deformation), as each point in the outer rim takes the shortest path possible, a straight line, to the next sample frame. A hexagon doesn't look very much like a circle! Make it 360 degrees over the full 12 frames instead (or more!!!) and it should look better (ie more samples per revolution)... or create a node network yourself that fetches more samples per frames and calculate another type of interpolation.

MDD is really for softbody dynamics. You should use BDD or whatever the hardbody equivalent is named. And perhaps NT should merge the formats.

04-12-2012, 01:41 AM
Just an image to illustrate the likely problem.

The wheels actual size is the outer circle, but you get something like the inner smaller circle on every other frame as you have only 6 actual sample points and the mdd playback plugin only does a linear interpolation of the previous and next frame sample. Naturally, the more samples you have per (one) revolution, the closer you will get to the perfect circle.

04-12-2012, 02:38 AM
or simply rebake the original anim with subframes, ie. set the framestep to something smaller than one. 0.2 for instance will cache 5 inbetween frames into your mdd.
It works like charm. I was actually the one who bitched about the lack of subframe mdd baking enough that it got implemented in 10.1 ...

You're welcome.

04-12-2012, 02:46 AM
I was not even aware of that. Cool. Thanks!

04-12-2012, 06:28 AM
You guys rock! :bowdown: Thanks for the heads up. Your help is much appreciated, thank you both!:thumbsup: