Natural Scene Calibration

Overview

  • This calibration relies on a mostly static scene

  • This approach works by tracking features (corners) from frame to frame

  • If the scene changes too quickly, the tracking can fail. Any data collected after this point will not contribute to the calibration

  • Camera placement and movement is critical

    • Keep the camera pointed in the direction of travel

    • Ideally, move the camera in a figure-8 pattern targeting a 3 meter diameter per loop

    • Make only one complete figure-8 pattern

    • If a figure-8 is not possible, target a single, closed loop of approximately the same size

    • Try to stay between 3 and 10 meters away from walls

    • Avoid repetitive patterns on walls and floors

    • Avoid reflective materials

    • Avoid moving objects

    • The data collect should take approximately 90 seconds

    • Rotating too fast can cause tracking to fail as features can leave the field of view before the next frame is captured.

Calibration Prep

  1. Download the latest program and firmware versions

    1. https://github.com/carnegierobotics/featureDetector/releases

    2. https://github.com/carnegierobotics/featureBasedCameraCalib/releases

  2. Install the programs

  3. Flash the firmware

    1. Firmware Update — MultiSense Docs

Running the Calibration

  1. Open FDV

  2. Comm -> Connect to the Camera

    1. Connect to the camera

    2. Choose settings

      1. Left-Right for KS21 (stereo only)

      2. Left-Aux for S27 (stereo + color imager)

  3. File -> Record Log

    1. Choose a file name for your recorded log file

      1. Ubuntu does not accept special characters in the file name (space, apostrophe, etc.)

  4. Press the record button

  5. Move the camera in the previously described pattern until

    1. The score is >80

    2. AND

    3. The log length is between 201 and 450 (indicated by the green colored progress bar)

  6. Click Stop

Fun Facts

  • The Left-Right and Left-Aux button only toggles the Aux checkbox

Processing the Calibration

  1. Open FBC

  2. Use the 3 dot menu by Feature Detector Log File to open the fdlog file

  3. Click execute

  4. Wait for the command to finish

    1. Should take at least 30 min

    2. The process is completed when the “results” tab appears

    3. If the process stops on the common tab or a numbered tab, the process has failed

Fun Facts

  • Open CALV to view the calibration’s progress

    • Open CALV

    • Click COMM -> Connect to Server

    • Click OK to accept the default settings

Loading the Calibration

Use either MultiSense Viewer or LibMultiSense to load the results

  • sfm_calib_extr_1.yaml and sfm_calib_intr_1.yaml for 2 camera systems (KS21, etc.)

  • sfm_calib_extr_all.yaml and sfm_calib_intr_all.yaml for 3 camera systems (S27, etc.)

Multisense Viewer

MultiSense Viewer

  • This option does not give feedback on a failed calibration upload attempt

LibMultiSense

LibMultiSense — MultiSense Docs documentation

If desired, confirm that the correct calibration was loaded by using either MultiSense Viewer or LibMultiSense to pull the calibration files off of the camera and compare them to the calibration that was expected to be loaded. Note that the calibration files may use different number formatting. For example, scientific vs general number formatting.