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Quality loss during Motion Tracking

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Quality loss during Motion Tracking
on Aug 17, 2007 at 10:53:23 am

Hi all,
I'm working on a sequence where a camera on a jib pans and tilts over a supermarket isle showing the labels of the produce. For copyright reasons, I have to replace one of the labels with one of our own, with the intention of soloing the Label from the BackGround video and a voiceover detailing the information on the label as it fills the screen. (Exciting huh!?)

I created the label in Photoshop, saved as PNG then imported it into Motion. I then added text to the label from within motion and then added a 4 point Matchmove to the group containing both the PNG label and Text objects. The motion tracking element worked really well. And the edges of the label stay fixed in the right position. Very smooth indeed.

The issue I'm getting is with the detail on the PNG label and the text I've added to the label from within Motion. Lots of jaggys; infact no smooth lines during the whole matchmove process. It does get a little better when the matchmove slows down a little (as the camera comes to the end of its move) but it could look better. In fact the text is pretty much unreadable during the whole move, especially compared to the labels visible in the BG movie.

I've added a Gaussian Blur which helps a little, and deinterlacing did nothing (I didn't expect it to seeing as my final output is PAL DVD) but the label I created still stands out way more than it should. It still looks (In my eyes anyway) that the label HAS has been added to the BG movie, compared to the other labels visible in the BG movie, which although are just as out of focus, move a lot more smoothly and look like they belong.

I can only think that it has something to do with the image res. Would it work better if i bought the label in to Motion as a vector graphic or will that not make a difference? Is the problem because the original PNG will fit the screen at full res, but for the matchmove is reduced to a 10th of it's size?

Thanks in advance!


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Re: Quality loss during Motion Tracking
on Aug 17, 2007 at 3:03:56 pm

Hey Simon,

It sounds like you're seeing artifacting from the extreme scale-down. Do you have the project's render-quality set to Best? This forces better quality (smoother) filtering on transformed images. As with any app, though, performing a large scale-down on an image forces you to choose between sharp & chunky or smooth & blurry, depending on the filtering settings.

Try to have your source image be as close to its onscreen-needed size, as much as possible. Or, as you suggested, you can use a vector-based file, like an Illustrator file or PDF. The vector file can be rendered at whatever its screen-size is, so it would always look optimal.

To set the render quality to Best (if you haven't), go to the 'View' menu in the Motion toolbar. You'll find the render quality settings most of the way down. Keep in mind that Best mode incurs a performance penalty, so I'd only toggle it on to do checks and for final output.

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