Take say a 600x600 .png with a 500x500pcx circular logo in it. apart from the logo the rest of the frame is transparent. Drop this into a composit in Vegas, use event pan/crop to scale it to a suitable size, works as advertised.
Now use 3D track motion to make your logo spin. Add another 3D parent to make your spinning logo float accross the screen. Looks OK, until you render it out and watch carefully.
At the point where the logo is 90deg to the camera the alpha channel gets lost. The result is that for a couple of fields (In my case the problem seems to affect 1 field in one frame and another in the next) the logo jumps in size by 20%. This unwanted effect is most apparent when the motion accross the frame is highest, making the object appear to jump once every revolution.
I was feeling pretty chuffed that I'd finally mastered multiply nested 3D parenting and then this :(
I can probably fix the problem by cropping the original .png to remove the surplus transparent pixels however I've decided that visually the FX doesn't look so appealing even without the bug. Still the bug should be fixed.
Bob.
Now use 3D track motion to make your logo spin. Add another 3D parent to make your spinning logo float accross the screen. Looks OK, until you render it out and watch carefully.
At the point where the logo is 90deg to the camera the alpha channel gets lost. The result is that for a couple of fields (In my case the problem seems to affect 1 field in one frame and another in the next) the logo jumps in size by 20%. This unwanted effect is most apparent when the motion accross the frame is highest, making the object appear to jump once every revolution.
I was feeling pretty chuffed that I'd finally mastered multiply nested 3D parenting and then this :(
I can probably fix the problem by cropping the original .png to remove the surplus transparent pixels however I've decided that visually the FX doesn't look so appealing even without the bug. Still the bug should be fixed.
Bob.