A vr cluster made of Raspberry Pi. Performance, Cost, is it the good choice ?

[Kosen]

Good afternoon VRGeeks.

I'm actually thinking to build a VR cluster for a school project.
The idea is to use it to do real-time simulation and interaction between multiple user.
Unfortunaty I don't I elknow if the a Beowulf cluster made of Raspberry Pi can handle it.
I know it possible to do everything I want with anything, the main problem will still be the price ^^.
Is it worth it to use a bunch of RPi do so. I also thought to use low cost solution, with high graphical capability such as old game console (Playstation 2 / Xbox).

thanks for your help

Kosen

[Kosen]

I struggle a bit to post, sorry for the misspelling you can found

[Jan Ciger]

On Thu, Jun 13, 2013 at 9:32 PM, Kosen <remi.c...@gmail.com> wrote:
> Good afternoon VRGeeks.
>
> I'm actually thinking to build a VR cluster for a school project.
> The idea is to use it to do real-time simulation and interaction between
> multiple user.

Why exactly do you need a cluster? What sort of application is this
going to be for? The only case where clusters are used for VR is when
you need to power multiple displays from a single simulator (e.g. a 6
sided CAVE, you often have 3 machines driving 2 sides each + one
master). Another possibility are large simulators (think military
battlefield sim) where there are many networked machines each
dedicated to different tasks, e.g. user input, image generation,
opposing force AI, control stations, etc. (so not really a cluster as
such, more a network of interconnected machines). You *do not need* a
cluster to do a multi user VR per se (think a multiplayer game - every
user has their own PC/console, but they aren't clustered).

Clustering Raspberry Pis is not going to be of much use - it would
certainly be educational, but that hardware does not have sufficient
horsepower nor memory to do some meaningful 3D, most Linux distros
available for Pi don't even have support of hw accelerated OpenGL/ES.
Clustering won't help anything there, because cluster helps you by
splitting a computational workload between two (or multiple) CPUs over
network, then you must merge the results back together. It is not
useful to speed up driving of a single display. Furthermore, the
development would be quite complicated due to the need to
cross-compile everything for ARM. I think you would be a lot better
off with something else.

Also forget the old PS2/XBox - there are no meaningful development
tools for those and the hardware is extremely limited by today's
standards. You could put Linux on the old XBox, but then you will only
have an extremely slow PC with no accelerated 3D. For PS2 I believe
that there isn't even a way to develop custom code for it unless you
have the official development kit. There was Linux available for it
from Sony, but again it was extremely limited and the official support
is long dead for it.

Depending on your exact needs, I would rather look on one or two good
PCs. These can easily support multiple simultaneous users and the
development would be a lot simpler, because you could use standard
tools. I understand that you budget is limited, but if you add up the
cost of all the time, effort and tools you would need to make your
project work with something like a cluster of Pis or XBoxes, I am
quite sure that the PC would come out cheaper in the end.

Regards,

J.

[Kosen]

Sorry for answering in late.
The main idea is to gather two field of study who interest me (clustering and VR).
I saw some cluster running onto RPi therefore I thought it's was possible to use the H264 chip to do something.
Thank for your answer I will consider them.

[Jan Ciger]

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On 06/22/2013 01:00 AM, Kosen wrote:
> Sorry for answering in late. The main idea is to gather two field
> of study who interest me (clustering and VR). I saw some cluster
> running onto RPi therefore I thought it's was possible to use the
> H264 chip to do something. Thank for your answer I will consider
> them.

There is some work being done to get proper accelerated driver for
X11/Wayland + OpenGL/ES on RasPi using the VideoCore API, but I don't
think it is really usable yet. I think Qt has some sort of support for
it too, but I am not sure whether it is usable for graphics or only
for playing video.

You can program the OpenGL/ES stack directly if you want to work on a
really low level, but that is a pretty complex thing to do, especially
on a very low end platform like that. Unless you have a lot of
experience working on an embedded hw, I don't recommend going there.

Also, keep in mind that Raspberry Pi *does not* and will not support
normal OpenGL, only OpenGL/ES. So most 3D engines you may be thinking
about using are not going to work, because they don't support
OpenGL/ES on bare (no X11) Linux system.

Regards,

Jan


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