Using the NanoFlash anaglyph option with 2D monitors & grids??

[Bruce Schultz]

Maybe I'm a little off-base with this question, but I was watching a Transvideo 3D monitor the other day with definable distance grids enabled, (this was on Alister Chapman's Hurricane 3D rig in Burbank, CA) and I began to wonder. Could a similar but far less expensive 2D production video monitor which had the same definable internal grid system be used by utilizing the Nano Flash anaglyph output to "see" parallax. Obviously you can feed the NanoFlash anaglyph output to any 2D monitor, but the ideal would be to have the grids enabled and set at a definable distance, say 4% between each vertical line so you could set background divergence at 2% by using 1/2 the distance between the lines.

The Transvideo 3D monitor has this grid capability, but at a very high purchase price ($12K USD). I'm curious if there are other on-board sized 2D monitors which have the same dynamic grid distances ability. If there are such monitors, that would create another affordable on-camera 3D monitoring system thanks in no small part to the innovative developments from the Convergent-Designs NanoFlash team.

[Bruce Schultz]

Well I guess this isn't interesting anyone, but FYI I've installed a very low-tech answer to the grids problem. Following a conversation with a good friend and fellow CMLer Mark Weingartner who advised that I just measure out a piece of camera tape the width of the monitor screen and using basic mathematics compute 2% grid lines (this turned out to be 4.5mm distance between markings) placing the tape at the top of the monitor screen to measure distant background disparity.

It works, it's a bit of a kludge, but it works. I can easily see the background disparities and control them at 2% by keeping them between two markings. Grids generated by the monitor would be best, but necessity is the mother of invention . . .

[Alister Chapman]

I think the issue is that not many monitors can generate a user specified grid :o(

You could also print a grid onto some acetate and place it over the monitor. Perhaps there is a market for someone to produce a clear plastic disparity ruler with different scales for different common monitor sizes. The stereographer could then wear this around his neck as a "badge of office" while wandering from monitor to monitor to spot check the disparity. I guess if you were really clever you could produce someting like a slide rule where you can dial in the monitor diagonal and the percentage scale would then be correct.

[Bruce Schultz]

That's pretty much what I ended up doing with a piece of green camera tape and Sharpie markings calculated out at 2% which translated out on one particular monitor to 4.5mm between lines.

I remember an engineer friend building a tiny chip into BetaSP viewfinders that generated safe grid lines many years ago. I'm going to contact him and see if this is something that could be generated in-line to the incoming HDSDI signal for any monitor.

[Alister Chapman]

I suppose if you could find a monitor that can give two different safe areas, with one being programmable you could generate a pair of lines at the frame edges with the desired spacing. Either that or a user definable box of the correct dimensions.

[Tim Dashwood]

I tend to just use a ruler to check positive parallax. We have other high-tech tools available but when it all comes down to speed on set I just pull the ruler out of my pocket. Of course bigger monitors are better.

To determine the maximum positive parallax just

1. divide the width of your on-set monitor by the width of your target viewing screen in a common unit (inches or centimetres)
2. multiply the result by 2.5 inches or 6.5 centimetres (universally accepted average interocular)

So if I was shooting for a 30 foot wide screen (360 inches or 900cm) and my monitor was only 22 inches wide (56cm) then I would divide 22 by 360 giving me 0.06 (the on-set monitor is only 6% the size of the theatre screen) and then I would multiply 2.5 by 0.06 resulting in 0.15 of one inch or a little more than 1/8th of an inch (4mm).

This is one very good example of why big monitors are important on set. The Transvideo, Cinedeck and our proprietary analysis tools can zoom in to show you the background positive parallax but it is always best to at least have a 46" monitor and a ruler close to a 3D set. In the same situation (shooting for a 30' screen) the maximum positive parallax on a 46" monitor would be 1/3 of an inch.

[Pavel Houda]

You are so knowledgeable Tim, that must be why, when I was passing a 3D production crew the other day, they used something like 46 inch main alignment monitor: YouTube - yt3d: 3D Production on the Beach of Waikiki , or better yet: YouTube - yt3d: 3D Production on the Beach of Waikiki - 3840x1080x2 . Happy New Year All!