getting the timing of exposure

[MGoto1]

I want to get the timing when D415 starts and stops exposure.

Can I get that from the pin 5 of GPIO connector?

Have you any more information about this?

[MartyG]

Assuming that exposure will start and stop when the stream starts and stops, if you want to get the exposure at that moment then you could maybe use frame metadata, with an instruction such as RS_FRAME_METADATA_ACTUAL_EXPOSURE. This instruction could be placed at the points in a script where the pipeline is started and stopped, so that the exposure value is returned each time the stream starts and stops, and not at any other time during the stream.

https://software.intel.com/sites/products/realsense/camera/rs_8h.html# a456ebb0504ac96e39b5e06e6b757395da890d92be4dc8460ef69ae3886190233e Intel® RealSense™ Cross Platform API (librealsense): /Users/mcurfman/ws/Linux_SDK/realsense_documentation/librealsense/s…

[MGoto1]

Hi MartyG

Thank you for your quick reply.

But now I want to use D415 for multiple synchronous system.

So I should use hardware trigger form D415 with the other Digital camera.

Could I get any hardware signal indicating the timing of exposure?

[MartyG]

I apologize for the delay in responding, as I was thinking very carefully about your question. If I were approaching the problem myself, I would take the exposure time from the stream of the master camera (assuming all the slave cameras are set individually to the same exposure value), since the slave cameras are following the master's lead in terms of sync timing.

[MGoto1]

Let me explain my situation about the system in detail.

The system gets depth data from D415, and gets texture from another Hi-reso-camera.

D415 will be operated free-run.

But RGB camera should be synchronized with D415.

So it is comfortable to get the trigger signal from D415 and put it into RGB camera.

Do you have any solution about that?

[MGoto1]

By the way, we use D415 at 40 units per 1 system.

[MartyG]

Could you please clarify me if all the cameras you are using are RealSense D415 cameras, please. I wanted to check because I was not sure if the RGB camera you mentioned was a non-RealSense camera. Thanks!

[MGoto1]

Our system mainly uses D415.

Now I am going to add High-reso-RGB Cam to improve the texture refine.

I know it is enough to add the timing generator and provide trigger pulse to each camera, but it is too complicated.

[MartyG]

A complication with using a non-RealSense camera in a multi-camera arrangement is interference. RealSense 400 Series cameras do not interfere with each other when positioned close together, but a non-RealSense camera may experience interference. An all-D415 setup would be much more straightforward.

You can add additional texture to a scene indoors by using the projector component of the D415, which protects a random pattern of dots onto surfaces that lack texture (e.g walls, doors, etc) to add texture detail to them so that the camera can analyze them better. Or you can use an external projector. An LED projector can produce a dot pattern that creates less depth noise than the internal projector of the D415.

If your scene is outdoor and there is strong light, the camera actually performs better, and texture detail is increased.

Cabling is not absolutely required for syncing. It is best used when micro-second precision in the syncing is required.

You may find notes from Intel's recent online seminar about multiple cameras useful to your project.

[MGoto1]

Thank you for your information in detail.

I will evaluate how much interference are there in RGB cameras.

But does the LED on D415 emit NIR wave length, doesn't it?

Is it not enough that I chose camera with IR cut filter?

OK, I will evaluate.

[MartyG]

Giving your scenario further thought, I wonder if interference would in fact occur if you were using the non-RealSense camera for an RGB stream only, with no IR projected from it, since it is just an ordinary video image and not an infrared pattern.