motion blur with moving camera also on 2d layers?
by the fakob
on
May 31, 2006 at 11:00:04 am
motion blur with moving camera also on 2d layers?
i wondered if it is possible when you have an animated camera to have motion blur on 2d layers. my setup is the following. after 3d tracking a video and modelling i rendered the 3d camera with different layers (shadow, highlight ...) to get them composited over the video again in after effects. this works fine, but to save some time i thought i will render the motion blur in after effects. so i imported the camerapath into after effects and turned on the motion blur buttons (for the comp and the layer). but i figured out that only static objects in 3d space get the motion blur. layers which are still 2d are not affected. the thing is i can't transfer my compositing into 3d as the position will get screwed up. also with auto orienting towards camera i am not able to get the right position.
is there a way to solve this problem to get the motion blur maybe with an expression onto the 2d layer?
Re: motion blur with moving camera also on 2d layers? by Steve Roberts on May 31, 2006 at 2:37:06 pm
No matter how much you move the 3D camera, a static 2D layer will not change its appearance. In other words, from the camera's POV, the 2D layer does not move. As a result, the 2D layer will not blur due to motion, since, relative to the frame, it is not moving.
It's like clamping a postcard to the camera: there's no motion blur on the postcard, because there's no motion seen.
However, if the 2D layer is moving relative to the frame, because its position has been animated manually, you will see motion blur on the 2D layer. This blur is not affected by anything you do with the 3D camera.
Re: motion blur with moving camera also on 2d layers? by the fakob on May 31, 2006 at 2:52:56 pm
thanks for replying
this sounds totally logic and the postcard example visualizes this perfectly.
but do you see a way of solving this problem with expressions. like reading the camera movement from frame to frame and calculate velocity and direction and map them onto a directional blur on the 2d layer.
the easiest way is definitely to render motion blur out of the 3d app, but somehow i thought that there is a faster and therefor more controlable way in post.
Re: motion blur with moving camera also on 2d layers? by the fakob on Jun 1, 2006 at 8:02:40 am
thanks chris.
i just registered at creativecow yesterday and as these are my first postings they are delayed so i haven't seen your reply when i sent mine.
as i don't have this plug-in i never thought of this possibility. but if this is the only way to get there i will definitely have to test it.
jakob
Re: motion blur with moving camera also on 2d layers? by Chris Smith on May 31, 2006 at 3:12:42 pm
This can be achieved by redering out a motion vector pass from your 3D app when you render the other passes. This motion vector pass can be used in a plug-in like ReVision Motion Blur. This will apply accurate MB to your 3D layers in the 2D world.
