Blender 2.45 animated roto splines - Greg Notzelman
Click here to see the test movie
right click - open in new window
Goals of this tutorial:

1) To show Blender is capable of film resolution animated roto splines.

2) To understand what could make the process faster and easier within Blender.

Please note:

1) I am not a Blender expert and this is my first tutorial. I welcome input from the Blender community on how I could improve this tutorial and make it better.

2) I used film footage from a prior movie that I worked on. I did this because it was the best example for this tutorial at the time. I had worked with the footage in other programs. This gave me a direct comparison.


1) Blender 2.45 is capable of making film resolution animated roto splines for matte generation.

2) A script to automatically assign hooks / empties to each control point on a bezier curve would speed this process up dramatically.

Aligorith' made this script to fix issue #2 (Thank you!)

3) The hooks clutter up the camera view when animating the roto spline. I am not sure what the answer is here.

4) For small roto jobs this is an acceptable technique. Obviously commercial composite packages are better suited for this type of work. But remember Blender is so much more than a 3d program.
Blender can render in EXR format with a built in compositor! It's capablities keep getting better by the month!

You can find out more about Blender at the link below.
Markus Opermann made this PDF for you Tutorial in PDF format Thanks Aligorith and Chris Cherrette.
The tutorial starts below
It is in 3 sections.
Each section is denoted by a red, green and a blue bar.
Note: this tutorial assumes you are familiar with Blender to some degree.
Part 1: Setup and making a roto spline
Step 1: Select your camera and set it to render orthographically. Step 2: Change your camera settings to match mine. (hint: press "n" to bring up the parameters window)
Step 3: Set your windows up similar to the image above.
You need access to the following:
Camera view
IPO curve editor
Step 4: Add a background image to your camera view that you wish to use for making an animated roto spline.
Step 5: Select 'Auto Refresh' so your view will update with changes in the timeline. Step 6: Add a bezier curve so we can begin making our roto spline. Align the first two points with the edge of what you would like to roto.
Step 7: Make your camera view full screen (cntrl + up arrow) Step 8: Set your background image to .50 to .70 blend in the Background Image dialog box.
Step 9: With your initial bezier curve aligned with what you would like to roto, select the endpoint and extrude the curve making it longer. Note: By selecting a control point you can have the bezier handle broken so that each may be changed freely.
Step 10: Continue extruding your bezier curve and outlining what you would like to roto. Step 11: Same as 10 (I say with a grin) Continue extruding your bezier curve and outlining what you would like to roto.
Step 12: With the end point of your bezier curve selected close the curve. (press C)
Step 13: You have successfully completed a non moving roto shape.
If you don't need to animate the roto shape skip to the last part (Composite is the blue section.)
Part 2: Animating the roto spline
Note: I have changed the frame and you can see the roto spline (bezier curve) no longer matches the image. We will now animate the roto spline. Step 14: In edit mode , we need to add a hook to every point on the bezier curve. (cntrl + H) We are adding hooks so that we may animate each point in the IPO curve window.( You can also add them to the handles. for this tutoirial I will not be doing that. A script to add a hook to every control point would speed this part up greatly.
Note 1:You will now have something that looks crazy with all the hooks and their axis's showing.
Note 2: notice the outliner has been populated with 30 hooks or so.
Step 15: Add a local keyframe for every hook you have added.
Step 15: Enable auto keyframes in the time line. This will enable us to get past the tedious part of the setup and freely animate the mask. (roto spline)
Step 16: In the outliner make the curve and the camera unselectable. This is so we can use the "a" and "b" (box select) key and we will only be selecting the hooks / empties .
Step 17: Continue to animate your roto spline until you are satisfied.
Step 18: Above is an example of moving all empties / hooks at the same time. We are now ready to go in compositing mode and output our matte. Note: Above is an example of moving two empties / hooks at the same time.

:1) Blender experts please let me know if there is a cleaner way of doing this. This would clean up the display. (You can scale the hooks down but it affects the tension of the spline.)

2) You can also rotate the empties/ hooks and this will adjust the curve of the roto spline.

Part 3: Composite and output of mattes
Step 19: Next set your windows up similar to mine. You will notice a Render Layer node appears. This is your roto spline.
Step 20: Next set up your nodes similar to mine. I will assume you have some experience with nodes and not explain every one. I am use to Shake, so I am still becoming familiar with Blender's nodes.
Step 21: Render out your "Composite node" in the format of your choice with alpha information. You now have either a matte you can use or footage to composite directly over other backgrounds.
=The End =
Greg Notzelman - Blender Roto Splines -