Multiple Camera Support of D4 VPU / RGB Calibration on D430 Module
1. When changing a custom RGB camera on an Intel D430 module, is it possible to set the intrinsic & extrinsic parameters of the RGB camera? If possible, where and how? Is it possible only on the CPU of the host computer, not on the D4 VPU stage? I prefer to set/initialize those parameters on the D4 VPU.
2. Can I connect multiple D430 modules on one D4 VPU chipset board? Based on website information, it says "x5 multi-camera support". If it says multi-camera here, can I connect FIVE D430 modules via Mipi? Or is it talking about five(?) cameras (L / R IRs, L / R Imagers, and RGB camera) in ONE D430 module?
If I can connect five D430 modules to one D4 VPU chipset board, how does it process for each depth in what order, and what are the pros and cons? The advantages I expect are bandwidth, heat, and price.
3. Does the Intel ROS wrapper have to launch each node per D430 camera? Or can multiple cameras be handled by one ROS node? If possible, how many cameras are handled by one ROS node? If so, does it publish each msg for each camera? In what order and how? If multiple cameras are processed in one node, is there any expected load?
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1. A RealSense integrator who was constructing their own design from individual parts said "From my understanding these (the imagers) are just standard MIPI CSI-2 camera modules (OV9821 and OV2740), so any modules with similar spec (MP/s, etc.) should work".
The free public version of the calibration software for the 400 Series cameras can only calibrate extrinsics though. To calibrate both extrinsics and intrinsics, an OEM version of this software is required. The easiest way to obtain this software is to purchase the $1500 USD "OEM Calibration Target" system from the official RealSense Store. This large-scale calibration board, which is aimed at engineering departments and manufacturing facilities, is designed for calibrating multiple RealSense cameras and enables connection to cameras through a remote Linux server.
https://store.intelrealsense.com/buy-intel-realsense-d400-cameras-calibration-target.html
Camera calibrations can be written to flash memory storage on the the camera hardware. The data sheet document for the 400 Series cameras states that the EEPROM where the calibration data is stored is on the Depth Module, not the Vision Processor D4.
2. Usually, one Depth Module board is paired with one Vision Processor D4 Board. I have not come across setups where multiple Depth Module boards are associated with a single Vision Processor D4 Board. The product brief for the D4 suggests that it is talking about connection of up to 5 MIPI CSI-2 camera imager modules, not five complete cameras.
https://www.mouser.mx/pdfdocs/Intel_Vision_Processor_D4_ProductBrief.pdf
3. The links below have guides to using the 400 Series cameras with ROS using 2-camera and 3-camera setups. I hope that these will help to answer this question.
https://github.com/IntelRealSense/realsense-ros/wiki/Showcase-of-using-2-cameras
https://github.com/IntelRealSense/realsense-ros/wiki/showcase-of-using-3-cameras-in-2-machines
For expert advice on ROS, I recommend posting your questions on the RealSense ROS GitHub forum by visiting the link below and clicking the 'New Issue' button.
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I have follow-up questions.
1. When changing a custom RGB camera on an Intel D430 module, how can I set the intrinsic & extrinsic parameters of the custom RGB camera on the D430 module?
Why is "OEM Calibration Target" system too expensive? Even though I purchased Depth Module D430 + Vision Processor D4 Board Bundle (10 Pack), do I need to purchase the OEM software as well to calibrate each RGB camera sensor per module?
Is the EEPROM the flash memory storage on the camera hardware module to store the intrinsic & extrinsic parameters of the custom RGB sensor and depth sensors?
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The cost of the OEM Target Board is mostly the cost of manufacturing the physical board. As far as I know, the only other way to get the OEM software is if you have a Non Disclosure Agreement (NDA) relationship with Intel, which can be difficult to qualify for. So the OEM board is the easier way to obtain the software.
I believe the reason why the free version does not support intrinsics calibration is that Intel believe that calibrating the extrinsics has much more effect on the camera image than changing the intrinsics does.
I have not heard of anyone who was constructing their own camera from the Depth Module and D4 feeling the need to purchase the OEM Target board too, unless it was for the reasons of calibrating multiple cameras or using the OEM system's ability to connect to cameras remotely via a Linux server.
According to the data sheet document the EEPROM on the depth module stores the calibration data, yes. RGB can be calibrated if the device supports it. My understanding is that the firmware driver detects a D430 without RGB as 'D430' but identifies it as 'D435' if an RGB imager is detected as being connected.
Details of how the Dynamic Calibrator handles RGB calibration can be found in its PDF user guide. If you search the document for 'rgb' then it makes it easy to browse through all the parts where RGB calibration and the writing of its data is discussed.
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