master / slave possibilities?

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percramer
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master / slave possibilities?

Post by percramer » Tue Jun 21, 2016 8:57 pm

Hi All,

i am new to Ogre and i was wondering if anybody could comment my idea :-)

So for this project i have got 3 video projectors which CAN maken up 1 large screen. And that is in capitals because they are also used separately. So each of the projectors will have its own pc and ogre on it. This is a demand of the project, so switching to 1 pc with a multi head gpu card isn't an option. It is easy of course to have them run separately and do their own things. But sometimes it needs to be 1 large screen... And now i had this idea:

Have a master pc also. All 4 pc's will load the same scene (with all it's data). The scene is the width of the 3 projectors resolution. In this master/slave mode each slave pc will have its own camera in it's local ogre scene so it will only render the correct part of the entire scene (left/middle/right). The master will then do the actual playback of the show (let's call it a show) and it will then sync info about objects to the slave's. Kind of like a multi player setup. And now for some questions :

1. Do you think this system will work at all? I have looked at remote screens over lan (so no ogre installations on the slaves), but this is a pain to get sync between the projectors if we run in de large screen mode). And there was quite a lot of lag >2 seconds.

2. Any advise on an network library for this (paid isn't a problem). I have got a lot of experience with network programming in C#, but i wouldn't want to re-invent the wheel if there is already something out there for this purpose.

3. If this is workable would that mean that i could have a person walk from the left to the right and there wouldn't be weird body jumps around the part where we move from 1 screen to another?

4. Any idea's about the delay?

The next part would be to create some advanced setup with edge blending and geometrical correction, but first see if the global idea would be workable :-) Ow and if there are people on here that are experienced with this, than i am also willing to hire them.

Regards,

Per
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frostbyte
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Re: master / slave possibilities?

Post by frostbyte » Tue Jun 21, 2016 9:58 pm

1) why not...
2) RakNet( MIT license ) is optimized for this and has a c# binding
3) if all hardware( and drivers ) is the same/similar and sync is done right any quirks should be unnoticeable
4) with your kind of setup( one Ogre per one computer/projector ) there should'nt be any latency

btw: you only need the master to sync time/cameraPos/events/distribute initial data, i don't see a need for a dedicated master computer
i suggest you sync between projectors using wireless...

remarks: this kind of set up may not work well for special effects/plugins that generate random noise/procedural stuff( e.g hydrax/skyx )
remarks2: you can post a job offering in the recruitment sub-forums
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percramer
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Re: master / slave possibilities?

Post by percramer » Tue Jun 21, 2016 10:35 pm

Hi!

thanks for the quick response. It will be kind of a simulator, so the master pc wil have to do more then just control the ogre scene data. The nodes for the projectors will be small devices, like a Pi 3 (which runs Ogre actually quite good). They are all connected through a wired lan connection, i prefer that over wifi.

You are right about the job post, i just wanted to mention the option.

I guess i have got some reading and testing to do...
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Re: master / slave possibilities?

Post by frostbyte » Wed Jun 22, 2016 3:03 am

i must admit this kind of setup made very little sense to me...
now that i know the setup hardware, it make even less sense (-:

pi 3 gpu = 24 gflops = maybe ok for very simple low-res/poly scenes
integrated hd4000 = 300+ gflops...much better...1080gtx =9000 gflops (-:
not to mention the weak pi cpu and only 100mbit/s ethernet...you'll have hard time on complex scenes( big scenes or scenes with lots of animation effects etc.. )

the pi is kind of useless in this scenerio...
sounds like you're trying to build a Rube Goldberg machinehttps://en.wikipedia.org/wiki/Rube_Goldberg_machine

anyway: you can use shared-folders for ogre resources so you don't need to send resource data with a network-library
have fun (-:
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and miles to code before i sleep..

coolest videos link( two minutes paper )...
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percramer
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Re: master / slave possibilities?

Post by percramer » Wed Jun 22, 2016 9:18 am

I understand your point about the device used, i would prefer something else also. But some parts aren't up te me and this is one of them. The playout devices must be small enough to fit into DIN rail enclosures. So this will rule out a lot of devices, but if you have got any good ones to point out then sure do ;-) I don't know if an intel atom based device will gain much, but it is worth looking at.

I can't go into much detail about the setup since it is a bit classified still at this moment. But currently they are using PI 3 devices and they are running kind of like Digital Signage devices. Without any issues or problems i must admit. It isn't real digital signage, but that is the easiest thing to compare it to. But it isn't used for a high end 3d game and high fps counts aren't needed. Results like on here http://www.raspberryconnect.com/gamesso ... berry_pi_3 are good enough. Certainly with the new hardware support for OpenGL (http://phoronix.com/scan.php?page=news_ ... 016-Update)

Ow there are some projects that are pi sized but with gigabit ethernet, like the pin64. But i wonder if we really need that amount of network processing (but that can be tested of course)
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percramer
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Re: master / slave possibilities?

Post by percramer » Wed Jun 22, 2016 10:14 am

Hmmm my reply seems to be gone... But what i said in that post is that some of the specs aren't up to me and one of them is the form factor. It has to fit in a din rail enclosure. The are currently using PI 3's in a sort of digital signage way (can't tell to much details because some parts are still classified).

But i did some more research and there might be 2 other options which i can check out :

http://www.up-board.org/specifications/
http://www.lattepanda.com

Both run win10 and have got better graphics. But since they both run Win10 the old "which 3d engine" comes up again. We also looked at waves, but since they didn't support video on linux it wasn't an option. Their 2d system looks better though.
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frostbyte
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Re: master / slave possibilities?

Post by frostbyte » Wed Jun 22, 2016 8:13 pm

ok, i understand a little better now...no need for high fps or complex stuff...
just make sure that PI can handle your scene( stress-test ), if it does handle the load than your good to go...

for sure having this mini-intel-pc is a better option from the PI but only if you don't care about the price
you can check out http://www.compulab.co.il they have all sort of configurable options with a wide range of products

gigE is good especialy for cases where you want to run the scene on PC, compress the output and send it over LAN for presentation
anyway you can improvise with the PI [url]http://www.jeffgeerling.com/blogs/jeff- ... orking[url]

if think waveEngine works on linux, mono is now open-source( MS acquired Xarmin )
Ogre3d is very focused on..well, 3d (-:
2d side was left to the community to fill the gap, but ogre users are much more intersted in 3D
for 2d+some 3D i can recommend libGDX, if you are comfi with c# and don't mind the closed source/splash/price just go with Unity (-:
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the woods are lovely dark and deep
but i have promises to keep
and miles to code before i sleep
and miles to code before i sleep..

coolest videos link( two minutes paper )...
https://www.youtube.com/user/keeroyz/videos

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Re: master / slave possibilities?

Post by syedhs » Thu Jun 23, 2016 10:25 am

I have done something similar.. and it indeed works.
Yes, it is kinda multiplayer and the master will always instruct the slave to move according to its position and orientation. Slave will need to adjust orientation and possibly position too so that the view from three monitors are seamless.
But it is quite complicated because you need multiplayer engine run nicely too. And you have to transmit the packet as 60hz - 30hz will need quite noticeable lag. And last time I used raknet, there are times when the packet simply stops maybe because due to the network traffic algorithm (I forget the correct term). I used enet and everything is flawless.

However, the better approach is to simply use single powerful computer (CPU+GPU) and use Matrox TripleHead so that it use only one DVI and the output is then send to 3 monitors - it is very straightforward and minus the hassle of setting up 3 separate computers, cables etc.
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percramer
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Re: master / slave possibilities?

Post by percramer » Thu Jun 23, 2016 10:48 am

yes i would prefer a setup with a multi head card also. I do a lot of live video events and my pc with Resolume has got 10x a full hd output and runs just perfect. BUT for this project the is not an option, in this case that decision is not up to me...

I am not a real Unity fan but they do have : http://docs.unity3d.com/Manual/ClusterRendering.html
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