Decapod 1.0 Camera Calibration Instructions

Owned by Jonathan Hung
Last updated: Jun 15, 2011Version comment
3 min read

Left-Right Camera Instructions

Attach Cameras

  1. Attach cameras to a stable structure or frame that can be fixed in place.

Connect Cameras to Decapod

  1. Connect USB cables from the cameras to the Decapod system.
  2. Turn on the cameras.
  3. Press "Test Cameras"

Camera Support Test

  • If 0 supported cameras detected: Connect a pair of supported cameras. (identical models).
  • If 1 supported camera detected: Connect another camera of the same model.
  • If 2 supported cameras detected and identical models: Proceed to test capture.
  • If 2 supported cameras detected and not identical models: Connect two cameras of the same model.
  • If 3+ supported cameras detected: Only 2 cameras of the same model are supported at the moment.

Failure case:

  • If 2 cameras are supported, but there's an error ...

Test Capture

  1. Place your book into the cradle / surface.
  2. Aim the cameras so they each face a page.
  3. Click "test capture"
  4. Correct orientation
  5. Correct page order

Camera Positioning

  1. With cameras aimed at each side of a page spread, press "take picture".
  2. Review the test shot.
  3. Adjust your camera positioning to capture as much of the page as possible without introducing wasted space.
    • Each camera should be in the same relative position.
    • Do not use a camera's zoom function, reposition physically instead.
  4. Once satisfied with the results, lock camera into place (be careful not to shift anything).
  5. It's important to not move the cameras once your work has started. If the cameras do shift, please re-run the recalibration process.

Work in Progress Wireframe

Notes

  • We want positioning the cameras t6he last step as to avoid any accidental movement of cameras.
  • Camera positioning current requires connection to a Decapod system and the cameras are supported. Otherwise the user will have to find their own method to capture images.

Issues with Left and Right Camera Setup

To ensure good results when capturing with independent left and right cameras, the following conditions should be true:

  1. Each camera sensor is on a parallel plane to the facing book page (otherwise there will be perspective warping).
  2. The page surface is flat (otherwise there will be page warping).
  3. Each camera sensor is positioned so that the output image produces text sizes that are essentially equal in both images (otherwise there will be variable font sizes which will affect OCR and glyph generation).

It will be difficult for a user to achieve these three requirements without a fixed and stable structure upon which the cameras are mounted.

Scenario: Two tripods and two cameras

  • Manually adjust the tilt of the cameras so it is on the same plane as the book surface.
  • Manually adjust distance of camera to book surface so that text sizes are the same from both cameras (requires trial and error, and comparing output images from both cameras).
  • Manually flatten the book by holding down the pages, or by pressing the pages flat with a hard surface.
  • Once the optimal setup is accomplished, the cameras, tripods, and book must not change position or orientation.

(warning) The above image only depicts two axis (camera pan and camera distance).
Not depicted:

  • Camera pitch (the 3rd axis)
  • Book cradle setup with cross-shooting cameras. This adds additional variables like adjusting book angles, and curling caused by page weight / gravity.

In this scenario, there is a heavy user burden to ensure the physical set up is just right.