D435 Color and Depth Sync

[SMali10]

When the D400 series was announced, they were described as depth and color cameras that would be able to sync with other cameras of the same type.

It wasn't until after the devices began shipping that it was disclosed that the D435 would not be able to hardware sync between it's internal depth and color cameras. Only depth cameras between devices would be able to sync.

This was stated by Jesus from Intel:

https://forums.intel.com/s/question/0D70P0000069CN4SAM

https://forums.intel.com/s/question/0D70P0000069CN7SAM

As well as MartyG from the community forums:

https://forums.intel.com/s/question/0D70P0000068mcISAQ

https://forums.intel.com/s/question/0D70P0000069CNHSA2

https://forums.intel.com/s/question/0D70P0000069fOrSAI

However, this past week Alexandra from Intel stated that it was possible to have the depth camera of the D435 slaved to it's color camera:

https://forums.intel.com/s/question/0D70P000006GYNESA4

Has something changed in the firmware? Or is this a miscommunication?

Can someone from Intel please confirm whether or not color and depth sync is possible on the D435? Or if Intel is still actively working on solving this issue?

Thanks again.

[Alexandru_O_Intel]

Hello SMali10, Thank you for your interest in the Intel RealSense D435 Depth Camera. The hardware sync was added in firmware version 5.10.3. You can find more details in the thread below: https://forums.intel.com/s/question/0D50P0000490XJISA2/realsense-firmware-5103-release-notes-d435-hardware-sync-now-available More information on color depth sync can be found in the Alexandra’s comment from the thread that was linked. Best regards, Alexandru

[SMali10]

Hi Alexandru,

Thank you for the reply, and I apologize for the confusion.

My question was not about syncing the depth cameras between different D435 devices. It was about syncing the depth and color cameras of a single D435.

The issue is that Alexandra's comments contradict previous statements by Intel, and as far as I can tell there have been no announcements in the release notes that color depth sync has been fixed on the D435.

Can you clarify that it is possible to have any kind of frame sync between the color and depth cameras on a D435? If so how?

[Sahira_Intel]

Hi Sam, This is a bit of a complicated topic with a lot of subtle details. To make sure I answer your question thoroughly, I'll try to gather and reverse-engineer the firmware flows to provide a comprehensive answer for you. In the meantime, though, I can tell you that the details mentioned in this: https://github.com/IntelRealSense/librealsense/issues/2637 thread are correct in that when a single camera is streaming RGB and Depth at the same FPS and additional constraints are met (TBD) and the HW sync is activated with RGB being the master. Best Regards, Sahira Rizvi

[SMali10]

Thank you very much for the reply Sarah.

Just to confirm, this is true for the D435 and D435i? Multiple sources from Intel have said this is only true for the D415.

[JesusG_Intel]

You are right, Sam. This is true only for the D415. The D415's color and depth sensors are on the same board and, therefore, can be synchronized. The D435's color and depth sensors are on separate boards so they cannot be synced. Regards, Jesus Intel Customer Support

[SMali10]

Thank you Jesus,

Are you sure about that? Alexandru and Sahira from Intel seem to think that it is possible to sync the color and depth cameras on the D435.

If it the device does have this limitation as you have stated, I believe it is critical that Intel state so on their product page.

I can understand if there is some confusion among the Intel staff about which camera does what, but it shouldn't take two weeks and several people to get an answer. This is a technical spec as important as field of view and frame rate, and your customers deserve to know about this limitation before they purchase these cameras.

[MartyG]

Dorodnic the RealSense SDK Manager gave the following response on the RealSense GitHub site back in October 2018: "As far as I know D415 allows Depth+Color sync to another Depth+Color. D435 allows Depth to Color sync, and Depth to another Depth sync, but not Color to another Color, so at least one (or both) of the color sensors will not be synced. Perhaps firmware / hardware people will be able to find a solution in future update, but for now it is a limitation". 

[SMali10]

Thanks Marty!

Jesus can you please confirm if Dorodnic is correct?

[JesusG_Intel · Accepted solution]

Hi Sam, I apologize that I was mistaken. Sahira's answer, and Dorodnic's, above applies to the D435. Dorodnic is always correct :) Regards, Jesus

[SMali10]

Thank you Jesus!