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Digital Projection of Stereo Slideshows Charts and Visuals from a Workshop given at the 2005 National Stereographic Association Convention, Dallas Texas by Prof. John Hart Program in Atmospheric and Oceanic Sciences University of Colorado Boulder, CO 80302 July 14, 2005
Charts and Images Shown at the Presentation: 1 Title
2 References (links to sites with data/products/etc.)
3 Some advantages of digital projection over traditional film-slide projection.
4 Typical costs of digital projection. Note: ProShow Gold is available from www.photodex.com
5 How to set up a system.
6 Screens - a couple of good ones.
7 Polarizing high gain screen have strong directional properties. But viewers of 3D should sit near to the central axis anyway to avoid both light loss side to side and 3D distortion.
8 The geometry (or trigonometry) of stereo seating. Screen is red, width W. For a much more extended discussion on seating AND projectors see THIS.
9 If you sit outside the edge of the screen by q (in units of W), how far can you go before there is a one stop difference in illumination across the screen?
10 Given the above, how many people can watch a screen of width W .
11 After you choose a screen width, how many lumens of projector output (quoted ANSI) do you need? For reference, an Ektagraphic slide projector with f3.5 lenses and max-bright condensor ~ 1300 lumen.
Depending on room darkening, number 1/2 to even a full stop less may be OK. (Half stop = 75% or number quoted, Full stop = 50%). But the above numbers will knock you socks off in terms of brilliance in polarized projection. 12 Projectors for 3D projection need to be easily polarized.
Also, wide format "Home Theatre" projectors (1280x720 or 16:9 instead of 4:3 aspect ratio) can work well. Of course it is best to format your material to make maximum (i.e. total) use of the pixels of the projector. 13 A stacked pair of DLP projectors (XGA, 2500 lumen Boxlights).
14 Projection geometry. Most projectors with non-interchangeable lenses have relatively small D. This leads to keystone effects. Projectors with "lens shift" fix this problem. For a more mathematical analysis of keystone errors see the Projector Shootout article.
15 Typical polarization of an LCD projector (left), or rotated 90 degrees (so green is horizontal).
16 The method of polarization rotation used in the StereoBright system (courtesy, I. Weismann)
17 Low-loss polarizers for LCD projection from www.silverfabric.com
18 Characteristics of the LCD stereo-bright system.
19 Other high performance polarizers from www.silverfabric.com
20 Steps in making various formats using Stereo Photo Maker (freeware).
All files in each of the output folders should have the same names. What they are must be described in the folder name. Example. Parallel pairs are in the parallel pair folder and have names Stereo1.jpg, Stereo2.jpg, etc. The Left Singles also have names Stereo1.jpg, Stereo2.jpg, and so on. 21 The multi-rename facility of SPM - used to set up for batch conversion.
This facility allows you to rename camera sequences (like DSC12345, DSC12346, etc.) to more useful names. You can also strip off _L tags in the Left Folder, and remove _R tags from the right folders shown above. 22 The batch conversion facility of SPM. Parallel pairs or LR pairs => just about anything.
After making parallel pairs (saved as tifs, bmps, 99% high quality jpegs) I usually back up the parallels to DVD and portable hard-drive. 23 Using ProShow (http://www.photodex.com) to generate digital stereo slideshows.
Proshow makes PC executables (and is itself a PC only program). Once the executable is started up, the show is almost guaranteed to run perfectly. As in, I've never had one fail or make a single miscue (provided your player computer is fast enough - a lot of horsepower is needed to orchestrate complicated moves and transitions at higher than SVGA or XGA resolution without flickering and skipping). Proshow computes everything on the fly in the player computer, so this means the executable files are small and manageable. 24 Steps for making a simple show.
25 A typical directory setup for use with ProShow.
26 Physical projector setups for Ken Burns (pan,scroll,zoom) stereo slideshows.
Motion effects can be done with a single computer and projector if you are doing anaglyph projection. The same mode may be useful in sending movies or computer executable files to friends and family. ProShow can output many formats, but executables are the most accurate and of the highest quality. To use Dual PC's to play motion-effect slide shows you load one side (Left) into the left player computer and the other side (Right) into the right player computer. You must start both executables simultaneously from a ProShow startup menu. I did this by simply parallel wiring a dual pole single throw momentary close switch to the right click buttons on two $6 computer mice. Open up the mice and solder the switches. When the menu windows for both sides are on the screen, position the cursors and click the switch. Works about 80% of the time. Sometimes Windows is off playing with itself. Then it double escapes and try again. 27 Zoom, Pan, Scroll of stills.
Boris Starosta made a good philosophical suggestion - use motion effects for a reason, when such enhances the sequence. I like it for some flow too - but now I use it less than I did in shows made a year ago when Ken Burns Effects were so cool I felt I had to put them into every shot.
28 Methods for making KB effects
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