Re: 3 Channel OTW display
Angus Dorbie (dorbie++at++sgi.com)
Thu, 08 Apr 1999 17:09:01 -0700
Joaquin Casillas wrote:
>
> Angus Dorbie wrote:
> >
> > > Bemis, Suzie CEI-TACCSF wrote:
> > >
> > > We currently have performer running our front view OTW for a cockpit.
> > > I want to add two channels for side views. Is this as simple as
> > > creating two channels and offsetting the views from the front-view
> > > eyepoint? And just updating the two new channel views when the front
> > > view is updated?
> >
> > Yes, or you could simple chan share the position, they need to share the
> > same scene and sharing stuff like LOD & earth sky (with fog) can also
> > help. There are a few other tricks which are less well known like making
> > sure that localviewer lighting is enabled in the light model to minimize
> > lighting discontinuities across channels.
> >
> > >
> > > Is anyone familiar with the ONYX 2 and the IR graphics? Do we need
> > > the multi-channel option hardware to send the two new channels to the
> > > new displays? Or is the hardware built-in? Or is my question too
> > > vague and requires more information?
> >
> > You can get 2 channels from a basic system or if you go for the channel
> > option you can get 8 channels. You always have the video bandwidth to
> > drive 3++at++1280x1024_60Hz but obviously you'd need the 8 output DG for the
> > 3 channels.
> >
> > Ensuring the right graphics channel is output to the right video channel
> > is simply a matter of opening viewports in the right areas of the
> > framebuffer to match the channel layout you create using the ircombine
> > program.
> >
> > Cheers,Angus.
> >
>
> Hello. We are also managing a 3 channel display system (150º FOV, 3
> projectors, curved screen). The projectors need an overlap area to blend
> the edges of the adjacent channels, and we are not sure about the
> correct way to achieve this.
>
> One approach is to overlap the channels from performer code, letting the
> left and right channel to have a heading offset smaller than the fov for
> each channel.
Yes. This is correct and is what SGI does in it's own Reality Centers
which use SEOS PORDAS displays.
> Another approach is to overlap the video channels with
> ircombine, and have the performer channels with the same heading offset
> and fov.
No, the geometry is wrong. It's nice & easy to set up because you only
need 1 channel but it probably produce the wrong result.
> ..... We think the former is more correct than the latter, although
> if it would be possible to achieve the correct effect with the second
> approach we would be saving some extra drawing.
>
> Any suggestion would be greatly appreciated.
Both of these require distortion correction in the projectors, you will
go through an alignment process.
I'll be giving a very brief talk about this topic during the ITEC
friends of Performer.
Cheers,Angus.
--
"Microsoft's system was like a forest that hadn't had a controlled
burn in decades, just waiting for one person with a match to turn
it into a disaster. Melissa was Microsoft's fault. They left their
system wide open to this sort of abuse, they knew it could happen
and did nothing." -- Bruce Perens
For advanced 3D graphics Performer + OpenGL based examples and tutors:
http://www.dorbie.com/
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on Thu Apr 08 1999 - 17:09:06 PDT