stereo mode

[wezzoid]

Hi, how do I use this with the Compute Module to publish nodes for 2 cameras?

[realizator]

+1, the same question.
Raspbian supports stereoscopic mode out of the box (https://www.raspberrypi.org/forums/viewtopic.php?f=43&t=85012&sid=ec557617fabfa9942e5baeec16bf862c)

Raspberry Pi Compute module supports 2 cameras, and using a Pi devboard or ready-to-use boards like StereoPi you have native stereoscopic image.
I can help to develper by providing hardware for tests (StereoPi engineering version). @rohbotics, please contact me if you need hardware set for tests and stereoscopic implementation to your driver.

[rohbotics]

We use the same firmware and kernel as raspbian, so that side of stereoscopic processing should work.

Can you use our image (https://downloads.ubiquityrobotics.com/pi.html) , and see if you can get PiCamera to output stereo?

[realizator]

@rohbotics, it just works! :-) The only thing I did is put dt-blob.bin (device tree for StereoPi) in a boot partition to enable two cameras support.
Thank you!

[realizator]

@rohbotics, concerning @wezzoid question - how do you think, what is the simplest way to publish nodes for stereo processing?

[rohbotics]

I'll have to look into the mmal format for stereo, but the way to do it is basically publish 2 separate images and use stereo_image_proc for combining them into a stereo_msgs/DisparityImage in ROS.

A couple concerns:

• I think we will be limited to raw publishing, or will have to find a way to cut a jpeg in half to publish it separately
• Calibration, how do we save calibration data for each camera separately?

Also PRs are welcome :)

[realizator]

As an idea - you can use two cameras separately. In raspivid I use -cs 0 and -cs 1 to use cameras independently and simultaneously (in my case it is front view and rear view on a drone, not stereoscopic mode). The only disadvantage is not so good image synchronization in comparison with -3d single image capture mode.

But as first step for tests it may be Ok.
Is it possible to load and use two instances of your driver and two cameras simultaneously? Is this solve problem with separate calibration data for each camera?

[rohbotics]

Being able to do select a camera for each instance of the node would be a really good first step in supporting stereo.

I'll look into it.

[davecrawley]

Stereo is currently supported on the compute module. Can it be made to work on the RPi 3B+? CSI is able to support up to 4 cameras on the same bus so I'd expect to enable stereo cam we'd just need a different design of camera cable - is that correct or am I way off? David

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On Wed, Oct 17, 2018 at 10:08 AM Rohan Agrawal ***@***.***> wrote: Being able to do select a camera for each instance of the node would be a really good first step in supporting stereo. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#41 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ALDeVjOSubOE0se7CH2BohwWoi41zTkEks5ul2QogaJpZM4S8tkT> .

[wezzoid]

I used the picamera Python lib to get stereo working for my project (https://hackaday.io/project/159212-augmented-mekamon-robot) I put the camera in stereo mode, loaded the data in as an array, chopped it in half and published the left & right frames to ROS, basically. Doing it in Python is slow. To get around this I put the camera in top-bottom stereo mode, which means chopping the image data in half is just one 'cut' instead of one cut per row.

Here's my (amateurish) code: https://pastebin.com/RQ4DMBJj

@davecrawley the normal Pi 3 doesn't have the right pins exposed. Only the compute module allows this. Why Raspberry don't want to add a second CSI connector to their revised boards I don't know.

[realizator]

@wezzoid thank you for your sample code! It is right this example that we were looking for! I will try to combine it with @rohbotics camera selection support from his last pull request after tests.

[realizator]

@wezzoid thank you for your code sharing. After minor changes it works fine:

BTW I had tried to contact you on hackaday.io but did not received any answer. Are you still there?

[rohbotics]

@realizator That is very cool! Looks like I am going to have to pick up a StereoPi 😄

[realizator]

@rohbotics StereoPi will be available after our coming-soon crowdfunding (here is pre-launch page), but I can send you one of my current revision board for experiments right now. I just need your address for parcel.
I wrote you email to send2rohan@... but did not receive a response (possibly my message was marked as a spam). You can write me to realizator[at]gmail[dot]com
I wonder if it is possible to make stereoscopic driver for ROS like other stereoscopic cameras have. It will be compatible with original Raspberry Pi CM3 devboard and with StereoPi. Also we plan to do StereoPi schematic open source, and I hope some companies like Adafruit will help us to make this board mass-producted and available for DIY enthusiasts.

[wezzoid]

@realizator - awesome stuff!
And that StereoPi board looks VERY interesting!
I clearly haven't been checking my Hackaday, oops.