Connecting stereopi to two displays?

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MWaddell
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Joined: Mon Apr 27, 2020 12:32 am

Connecting stereopi to two displays?

Post by MWaddell »

I know it's possible to connect the stereopi to a single screen (and indeed this is a strength), but I want to do a project where I connect a single stereopi (with the two cameras) to two separate screens. More specifically, I want to connect it to two of these https://www.amazon.com/Vufine-006011-We ... 36&sr=8-10

You can see someone connect a single raspberry pi camera to one of them here: https://www.youtube.com/watch?v=px2hdZJLC3A&t=1s

My question is if it's possible to connect the stereoscope to two of these things (essentially displays that you connect to via an HDMI connection)? And if so, would I experience some of the issues the stereopi is meant to address (latency, differing delays between trying to sync two cameras before the stereopi came around, etc...).

Would love some guidance!

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Realizator
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Re: Connecting stereopi to two displays?

Post by Realizator »

Usually for the VR applications (like helmets) it is used a couple of screens (for each eye), but with a single HDMI input, like this:
https://imall.com/product/90HZ-VR-LCD-s ... -294047/ru
Or round screen (magic leap?) like this: https://imall.com/product/Wisecoco-Real ... 9225940/ru
You can find more options by googling.
So you just provide a single HDMI output, and hardware splits image on left and right.
As for your mentioned screen - I did not find any solutions for "splitting" image for such a glass-related tiny monitors.
You can look at tilt5 project - they use a couple of a tiny HD projectors for their VR glasses. But, to say the true, I was not able to find some more details on hardware they use.
p.s. If you decide to go this coupled-screen way, please take into account, that RPi can give you 1920x1080 maximum resolution (but not 4K) from the cameras.
Eugene a.k.a. Realizator

MWaddell
Posts: 2
Joined: Mon Apr 27, 2020 12:32 am

Re: Connecting stereopi to two displays?

Post by MWaddell »

Thanks, this is actually really helpful. I really just need the board that splits the images into two separate screens - I can figure out how to connect the displays I linked to it fairly easily I would think. I'll keep the forum posted!

AaronD123
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Joined: Thu Jul 29, 2021 4:24 pm

Re: Connecting stereopi to two displays?

Post by AaronD123 »

Using a splitter, isn't the total number of pixels/second across both displays (left eye + right eye) limited to what the Pi can push out of a single port? So a port-maximum of 1920x1080x60Hz means that I can't have a dedicated 1920x1080x60Hz screen for each eye?

It *could* however, be 1920x1080x30Hz for each eye, while the Pi runs at 60Hz, if the graphics driver and the splitter both work that way: odd full-frames to one eye, even full-frames to the other. Or side-by-side, but that guarantees a weird aspect ratio somewhere, either out of the single port, or into each eye.

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It seems to me that the "standard" solution of using a single output and splitting it, was originally to solve a problem that no longer exists today. Or at the very least, doesn't have to exist *here*. (I'll make a concession for a phone-based VR headset, as it still requires the side-by-side single-screen solution.) But why continue to require that solution with dedicated, purpose-designed hardware? Since the Pi4 and CM4 both have dual HDMI outputs, why not send a camera to each in 2D full screen? (plus possibly an application-specific overlay)

I know it would require a StereoPi v3 to bring out the second port, when the v2 is only a year old, but for someone just entering the 3D video and augmented vision space, it seems SO much more straightforward to just plug the two glasses-mounted retinal-projectors into their two connectors like you do for the cameras, and declare the hardware to be done.

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