Albert J. Hermann albert.j.hermann at noaa.gov
Mon Jun 14 12:58:55 CDT 2004


A few thoughts/questions about immersive viewing from a newcomer. We 
have a small project here to investigate low-cost immersive stereo with 
the AG (or even better, a simple PIG node) in conjunction with our 
Geowall. After a bit of web-surfing, we came up with a few possibilities:

Option 1 (single camera solution). Use a singe camera with a/v output, 
in conjuncion with a beam splitter attachment (e.g. the Canon Digital 
Rebel SLR in conjunction with the Loreo 3D lens-in-a-cap). This yields a 
single stereo image (like an old-style stereogram, but in video) which 
could be sent like any other single-camera video stream. There would be 
no synchronization problems with multiple cameras (as there is only 
one), but we would need to find a way to split the video frame on the 
receiving end, to feed it to the separate projectors of the Geowall (or 
use the brute force approach, of just shifting one of the projectors to 
overlap the two images)!

Option 2 (multiple camera solution) Use a couple of standard digital 
cameras with a/v output, in conjunction with a synchronizer (e.g. the 
Sync Shepherd and related devices preciously mentioned on the AG list, 
or the stereo cameras/synchronizers from Point Grey research), fed to 
two video capture cards (or perhaps there is a card which accepts input 
from multiple cameras). This yeilds two nice synchronized pictures to 
the sender's node, but what happens on the receiving end? I would think 
there would be synchronization problems, as the two signals may travel 
differently over the web. One could multiplex the two cameras into  a 
single video feed, but this again necessitates splitting them up on the 
receiving end, as in option 1). I would guess with the apporpriate 
device one could also multiplex input from two cameras into a 
frame-flipped stereo signal (or perhaps single cameras exist which 
produce this), but could the receiving node correctly unravel a 
frame-flipped video sent over the web?

I could well be missing something fundamental about the AG, which makes 
this process easier or harder than it appears. Any thoughts appreciated. 

-Al Hermann

Darin Oman wrote:

>This is way cool! We finally checked it out. The cameras are a little misaligned vertically, but I was able to adjust the window accordingly. One thing that might make it difficult for practical AG purposes is that the cameras are a little out of sync, so when there was a lot of movement, it appeared very choppy. I'm not sure how you could adjust that. We'll be playing around with this idea ourselves. One thing I'd like to try is messing with the focal point to see if you could get the image to come out at you rather than away from you.
>Cool stuff!
>On 2/9/2004 at 11:25 AM Tom Coffin wrote:
>>A couple of weeks ago the HASTAC folks were meeting
>>here at ACCESS and I was demonstrating for them the 
>>Accessgrid and Geowall technologies. During a conversation
>>at the geowall, David De Roure from University of Southampton
>>asked me if anyone had done the accessgrid on the geowall
>>and I replied not to my knowledge but it would be easy to
>>Well, time went on but I got an email from David asking
>>if I had setup the 3d ag. I hadn't but it got me to try it
>>and in under 10 minutes had it up and running.
>>Basically, took two cameras pplaced the closely side by side
>>and pushed their inputs into an accessgrid node. Then installed
>>the ag1.x pig software on our geowall machine and opened
>>vic inot our ACCESS-DC institutional venue. Then just opened
>>the two streams. Placed the right image to the right projector
>>and the left image to the left projector and bingo! 3D AG!!!
>>I have the two images up in the ACCESS-DC Institutional venue
>>and will leave up for a while. Feel free to drop in with
>>and check it out on your Geowall.
>>Tom Coffin .......................... tcoffin at ncsa.uiuc.edu

Albert J. Hermann
Pacific Marine Environmental Laboratory
7600 Sand Point Way NE, Seattle, WA 98115
e-mail: Albert.J.Hermann at noaa.gov
ph:  (206)-526-6495 fax: (206)-526-6485
WWW: http://www.pmel.noaa.gov/~hermann/

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