Rotoscoping in Blender?

I can put out a long-winded expwlanation and bore you as to why I need to know this technique but instead I am going to make it short and sweet.

I have footage of a man holding a lightsaber hilt and it has no reference beam (a wooden dolly attached to it) so I want to go into the video and add an object into the scene to follow his hilt. So how/can I follow the video frame by frame in blender keyframing a cylinder object to his hilt? or is that impossible to do?

It’s a lot of trial and error. First of all make a lightsabre in blender (look up tutorials on it, there’s a bunch). Then just use compositing nodes to place it on the video. To rotoscope, render the video, see how far the lightsabre is off, move the lightsabre mesh, re-render, and repeat until right, then just add a key-frame by pressing “i”. Blender can be a pain to rotoscope in, it will take forever, and give brilliant results.

After you have a model for your LS blade, you can match it in the X&Z axes in a 3D window by placing your reference video as a BG image/movie. If properly set up the BG image will update with each frame change so you can move the model and keyframe it to match the LS hilt position in the two planar axes. However, the depth axis (Y) and tilt of the beam toward or away from the camera may be a problem since there will be only scant visual references as to the actual angle of the hilt and how it moves in depth. This is one reason some sort of dummy blade is often used in the live action.

Once the action looks OK in “model over BG image” form, you can render an OpenGL preview “playblast” for slop-compositing over the live footage in the Compositor to check the moves at true playback speed. Once this looks OK you can be confident that taking the time to do the full render of the beam/blade, with Motion or Vector Blur if desired, will be successful.

Ok so how do I set up the video to go frame by frame? I’d imagine I set the movie as a background the same way I would an image?

An easy technique for rotoscoping and going thru frame by frame is in my book; consider picking up a copy :slight_smile: Foundation Blender Compositing.

No

way.

It

is

you.

You are so cool! I really want to get your book! I’ve been into compositing for a while and hope it will be a great book! Thank you sooooooo much for writing it!

-YA

Yep, that’s about it. The settings are pretty self-explanatory, similar to the way movies are set up in other contexts. The main things are to be sure Auto Refresh is enabled so the movie will update with frame changes (even scrubbing, which is handy), and to match the image aspect ratio (ratio of image width to height, e.g. if your BG movie is 16:9, make sure your output is also 16:9) of your output to that of the movie, so the BG movie will exactly fill the image space of the rendering camera. That insures an accurate fit for when you go to do the compositing.

I also suggest animating the xtremes of movement first then dividing the chunks to finesse the movement afterwards. So key the first frame to next extreme (movement) frame, then go to middle of those and key that frame, dividing as you go. Sometimes you don’t have to key every single frame.

take a look at this.

That’s often the case, though a lot depends on how much camera movement is in the live footage – f’rexample, a hand-held shot can have lots of little bumps and jiggles that make the image move erratically within the frame, even if the main motion appears smooth, and the model will need to match this, making many keys necessary. For match-moving a model more complex, 'specially one that shows perspective more obviously, it’d be a good idea to use some sort of camera-tracking 'ware, but I think that’d probably be overkill for a LS blade. Determining movement of the blade in scene depth could be a thorny issue, though.

Hi, in the past, I did a light saber trial using a real shot. For the sword, I used a slim blue stick with a handle.

By Chroma Keying, I erased the blue stick. In made a “hole” in the image.

In the video editor, I added a bright background on a layer under the main image.

I added a glow effect, and got a good light saber, not requiring any 3D editing !

unfortunately, I don’t know if I have kept the video file somewhere…

If you want a ready to use setup for Rotoscoping and Garbage painting, I have
made a PDF tutorial an a blend file available here :

http://3d-synthesis.com/tutorials/Roto&PaintingSetutp&Tut.pdf

http://3d-synthesis.com/tutorials/Roto&Paint-Setup.blend

Best regards,

Philippe.

cool idea Roubal. I guess you could have just used the key channel too as an overlay. But you might not get consistently good keys from the movement.