Calibration Requirements and Validation for Accurate Depth Measurement with Intel D435 Cameras on AMR
Hello Intel Community,
I am developing an Autonomous Mobile Robot (AMR) and have integrated four Intel RealSense D435 cameras for depth perception. Accurate depth measurement is critical for tasks like obstacle detection, navigation, and mapping.
I have a few questions regarding calibration:
- Is intrinsic calibration necessary for the D435 cameras?
- If yes, which calibration types should I focus on? Specifically, on-chip calibration, dynamic calibration, focal length calibration, or OEM calibration?
- What specific aspect of depth measurement or camera performance does each of these calibration methods affect?
- How can I validate if my camera intrinsics are perfectly calibrated? Are there any benchmark techniques or validation methods to ensure accuracy?
- How often should calibration be performed, and do factors like lighting, temperature, or camera mounting affect calibration requirements?
Additionally, since I am using four cameras simultaneously, should I be concerned about interference or inconsistencies between the cameras? Any suggestions for managing multiple cameras effectively would be greatly appreciated.
Thank you for your support and insights!
Best regards,
Vybhav Raghavendra Devarakonda
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Hi Spam Raghavendra Thanks very much for your questions!
1. The free (non-OEM) version of the Dynamic Calibration tool only calibrates extrinsics, so a healthy calibration can certainly be achieved without calibrating the intrinsics. To calibrate both intrinsics and extrinsics, the OEM version of the DC tool that is bundled with the $1500 USD multicam Calibration Target Board product is required. This product is targeted at engineering departments and manufacturing facilities though, and for most users the free version of DC is perfectly fine.
2. Dynamic Calibration / OEM Calibration can enhance the accuracy and depth image quality of the camera. On-Chip improves depth quality. To calibrate depth measurement accuracy, the Tare Calibration tool should be used instead of On-Chip. Focal Length calibration can correct depth distortion caused by an imbalance between the camera's left and right sensors.
3. If you use the On-Chip calibration tool then it provides a 'health check' score value that informs you how well the camera is calibrated. You can keep repeating the On-Chip calibration until you are satisfied with the score and then save it to the camera hardware.
The On-Chip tool only calibrates depth, not RGB, and it calibrates intrinsics. To calibrate both depth and RGB, it is necessary to use the Dynamic Calibration tool.
You can also easily reset the camera to its factory-new default calibration values in the RealSense Viewer tool.
4. A camera can become mis-calibrated and require recalibration if it receives a physical shock such as a hard knock, drop to the ground or severe vibration. Usually the camera does not need to be regularly recalibrated, but if you wish to establish a regular recalibration then once a week should be fine.
5. Multiple RealSense 400 Series cameras (including D435) do not interfere with each other when used in a multicam configuration. They can though interfere with non-RealSense devices nearby that use infrared.
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