View Full Version : Pixel aspect ration conversion question

06 June 2006, 05:54 AM

I need to create a scene that uses a square pixel digital camera image as a background/rotoscope for an ntsc (720/486) 0.9 aspect animation. I was going to pre-stretch the image, so that I get a correct pixel aspect, but I'm not sure if this is the correct way to do this. I've done this before, but I'm having trouble remembering if there is anything special needed. I have a feeling I may be overcomplicating this.

06 June 2006, 07:04 AM

There is an option in the rotoscopy, to set aspect ratio.

It's either following the pixel ratio of the image or pixel ratio of the camera. You of-course can set it to square too.

If you create a true circle in XSI, and render out with 0.9 pixel ratio, loaded to photoshop you will get an ellipse, but when it recorded and playback with NTSC device it will be fine.

I tend to use all square pixel when I'm working with XSI and rotoscope.


06 June 2006, 12:18 AM
Hello there.

I'd say there are two solutions to your problem.

1) Resize the footage that you're going to rotoscope to meet the 0.9 aspect ratio, as you said yourself, with the aide of Combustion, Premiere or whatever program you're using for creating composites.

2) Work on the footage as it is, but don't forget to render your scene with a 1.0 aspect ratio (720x540) so there's no problems when composing it with your footage, and then change the aspect ratio to NTSC.

My only concern would be your original footage. If it's 720x540, it'll work just fine. If its measures are NTSC like, but it still has an aspect ratio of 1.0, it won't.

Just my two cents.


CGTalk Moderation
06 June 2006, 12:18 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.