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Adjusting an image over another ?

asked 2016-04-11 14:12:30 -0500

Alemao gravatar image

I have 2 cameras , an RGB and IR, side by side. The photos are taken at the same time , but each has its lens distortion and different size frame. I can correct the distortions, but how do I adjust or rectify the IR band on the RGB . I need to merge the bands.

Sorry for my English!!

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answered 2016-04-12 10:28:43 -0500

You need to rectify your images (in a stereo rectify way) in order that each pixel of the IR image match the RGB image. Have a look at the stereoCalibrate function to see how to do that, and also at the sample cpp/stereo_calib.cpp for a working example.

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The problem with this is that keypoints for calibration in the RGB image will not necessarily be the same in the IR image... which could be a challenge. How we solved it in our lab, use a heated metal circle to calibrate the image in all positions. The circle center can be seen in the IR image and easily detected in the RGB image.

StevenPuttemans gravatar imageStevenPuttemans ( 2016-04-13 04:32:20 -0500 )edit

That's interesting! How do you heat the ring? Once for the whole calibration or all the time in a continuous process?

Mathieu Barnachon gravatar imageMathieu Barnachon ( 2016-04-13 05:58:29 -0500 )edit

We actually performed 2 steps

  1. A warm calibration, there is a current placed on the copper disc, which heats up the disc to a desired temperature. So it stays warm the whole time.
  2. A cold calibration, for this we placed a dinner plate inside the freezer for some hours, and after taking it out, it could be used for calibration for about +- 5 minutes, so we stockpiled freezed plates.
StevenPuttemans gravatar imageStevenPuttemans ( 2016-04-13 07:20:10 -0500 )edit

That's cool! Do you have some images to share? Also, I'm wondering if you manage to hook the OpenCV calibration process with your disc or if you really on another tool? Because I'm wondering if the calibrateCamera function works with a single point per frame. Anyway, thanks for sharing!

Mathieu Barnachon gravatar imageMathieu Barnachon ( 2016-04-13 07:34:14 -0500 )edit

Well it is not my work and the guy who did it cannot share the process since the system has been commercialised. And he did it in Matlab, but just saying that it is possible :P

StevenPuttemans gravatar imageStevenPuttemans ( 2016-04-13 07:40:37 -0500 )edit

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Asked: 2016-04-11 14:12:30 -0500

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Last updated: Apr 12 '16