D457 GMSL/FAKRA connection to a desktop PC
I am currently developing an interaction system using multiple D415 cameras to measure hand surface geometry. I am considering switching to the D457 GMSL/FAKRA cameras to reduce latency in the system.
As a beginner with limited knowledge in this area, I would like to know if simply purchasing a grabber board like this and connecting it via PCIe is the correct approach to connect the D457 GMSL/FAKRA to a desktop PC. Is there a more optimal solution for this kind of setup?
Additionally, if switching to the D457 won't significantly improve latency, please let me know.
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Hi Marocharoma For the application of scanning hand surface geometry, the data transfer speed provided by a GMSL/FAKRA connection would be unnecessary.
Your latency problem may be due to the D415 model having a slow 'rolling' camera shutter on both its depth and RGB sensors, This can cause lag or blurring if there is motion of the observed object that is faster than the waving of a human hand. Using an FPS speed of 60 can help to minimize this shutter-caused motion lag.
If the hand that is being scanned is relatively motionless then connecting multiple RealSense cameras to the same computer and having them active simultaneously can also cause slowdown, as each attached camera consumes a portion of the computer's resources.
For two cameras, a computer equivalent in processing power to an Intel Core i3 should be sufficient.
For three cameras, an Intel Core i5 or better.
For four cameras or more, a Core i7 or i9.
Camera models in the D455 class (D455, D455f, D456, D457) have a fast 'global' shutter on both the depth and RGB sensors that can handle high-speed motion.
If you do decide to explore switching to D457, a D457-supported computer product by Connect Tech at the link below would be an excellent option for a beginner. It can handle up to eight D457 on one system and it has the deserializer technology built in so that you do not need to purchase a separate derserializer board.
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Thanks for the useful comments!
I would like to ask more about the effect of delay. For example, if I compare the USB connection of the D457 with the GMSL/ FAKRA connection, can I assume that the delay time due to communication is almost the same on the order of ms?
Due to various restrictions in the system we are developing, we would like to use the D457 by connecting it to the PC I am currently using. If we purchase a deserializer board and install the driver, can we use it with the RealSense library in the same way as with the USB connection?
Translated with DeepL.com (free version)
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The D457 can be used with the RealSense library on a GMSL cable connection from version 2.53.1 onwards.
To make it work with a desktop PC, you will need to convert ("port") the MIPI driver for use with your particular desktop computer equipment and brand of deserializer board. Intel are unable to provide customers with technical assistance for this porting process, unfortunately.
Regarding purchasing a deserializer board for use with the D457, a compatible product is 'LI-GMSL2-IPX-DESER' by the company Leopard Imaging.
Other brands of deserializer can work though as long as they incorporate the MAXIM MAX9296A deserializer technology, like the Leopard Imaging board above does.
A USB 3 connection supports up to 5 Gbps (gigabits per second) data transfer rate and GMSL supports up to 12 Gbps. I do not have a comparison to provide of D457 performance on a USB connection versus a GMSL connection though. It is possible though that if a delay is taking place on the computer instead of the communications connection, the computer is going to act as a delay 'bottleneck' no matter what the data transfer rate is.
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