Team Little Green Dog's Calibration Example
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Author:  Greenlaw [ Sun Mar 06, 2011 9:41 am ]
Post subject:  Team Little Green Dog's Calibration Example

A few people have asked to see an example of an iPi Studio calibration video shot on our stage so here it is:

iPi Studio Calibration Video

The video first shows the data in RAW Bayer format, and then switches to the final result in iPi DMC. Some users may be surprised by the simple 'pattern' but it has given us accurate calibration results every time.

What isn't shown in the video are the steps for using the calibration video in iPi DMC but we don't do anything out of the ordinary. Basically, we set the BG segment to about 30 frames of the clean video at the footage head, and then set the ROI to start from the frame when the LED touches the floor for the first corner of the 'cage' and end when the LED touches to floor for the tip of the 'spiral'. Then in DMC, under the Calibration tab, we make sure to enable Auto Detect Initial Camera Positions and set the FOV. (For PS3 Eye cameras, use the default setting of 75 degrees.) Setting the lighting angle is optional for calibration but we set it to 'head on' to match our stage lighting anyway; we think it might help a little for the difference matte. To define a ground plane, we just choose the five contact points of the 'cage' (you need a minimum of three ground points.) Next we click the Calibrate button and wait for the process to complete. With a modest gaming card like the Nvidia Geforce GTX 220, it may take about 10 minutes. We recently upgraded to a GTX 460 so I'll post a time for that soon.

When the processing is done there is one step left to complete the calibration: set the known height of one camera. We usually use camera #1 but any camera will do. Remember to use the Ground Height Fine-tuning slider for extra precision. Finally, save your scene under the Scene tab. Save your Project file too just in case you need to run the calibration again.

Now it's time to track some performances from this session. Just load an action video and the Calibration scene file you just saved and you're ready to go.

Please feel free to ask any questions about the process here.


Author:  Greenlaw [ Sun Mar 06, 2011 9:59 am ]
Post subject:  Up next: Kinect Sensor

By the way, we ordered a Kinect Sensor camera. I'm sure our current six camera PS3 Eye setup is more accurate and flexible than a single Kinect but it occured to me that nearly all of the actions fo we captured for act I of 'Don't Fear the Pooper' probably could have been done using the Kinect system. We still need mocap data for this rest of the short film so it's a good time for us to test the Kinect version.

I'll write more about it after it arrives.


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