# geometry wars



## Dreadpoet (Apr 28, 2009)

I am re-examing a problem that I never got fixed and need help. I have a rather large projector (Sharp XG-V10XU LCD PROJECTOR). it is currently center focused and hung about 50' away (above the audience on our lighting beam) from our backwall which serves as cyc. I would like to move it all the way house right or house left and focus it on the same place. Where it is currently just is not feasible for having an actor, speaker, or singer on stage while it is on. 

The obvious issue this raises is that the Image will become distorted as it hits the wall at about a 30 degree angle. I do not have the keystoning ability to correct this....which stinks. For some reason, Sharp decided that anyone using this particular projector would only want to adjust it vertically, but not horrizontally.

When last I posted on this, which was a year or two ago...someone said that... 

"could also look at something like the Silicon Optix Image Anyplace http://www.flexiblepicturesystems.com/products/imageanyplace.html . This lets you manipulate the signal to correct for geometric issues in the display."

Would this act sort of like a keystone, or is this product simply going to fix the blurr that might occur when throwing an image at an angle? Perhaps you know of a product that might fix this issue. It is a great projector other than needing to have this keystone correction and needing a dampener for theatre purposes.

note: there is no other easy solution outside of keystone correction or simulating a keystone correction.


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## derekleffew (Apr 28, 2009)

There is a limit to how much any electronic image processing can actually help you, Dreadpoet. While such devices can help with shape (turning the trapezoid back into a rectangle) and focus across the image (one side sharp and the other fuzzy); they cannot defeat the http://www.controlbooth.com/forums/glossary/5549-inverse-square-law.html. The near side will always be brighter than the far side unless a graduated mask going from dark to light is used. This will seve to lower the overall brightness of the screen--meaning you would need to start out with a more powerful projector. Horizontal keystone correction of 30° is quite a lot--doubtful that Image Correction Geometry can solve this problem.

Yes, along with Gravity; Geometry, thou art a cruel mistress.


Dreadpoet said:


> ...note: there is no other easy solution outside of keystone correction or simulating a keystone correction.


Changing to Rear Projection might help. What's on the other side of the upstage wall?
OR, what about using a wide-angle lens and hanging the projector from the 1st Electric position, thus allowing the beam to shoot over the heads of performers downstage?


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## ruinexplorer (Apr 29, 2009)

The newest version of the Image Anyplace states that it can correct up to a 40 degree angle. 

Is the purpose of this to avoid the performers being directly in the projection and causing shadows? Since this projector can utilize other lenses, have you sought a replacement for either short throw for rear projection or long throw to have it at the back of your house? Yes the Image Anyplace can correct your image so that it appears that you are projecting from the front, but you end up losing the lumens as Derek mentioned.


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## museav (Apr 29, 2009)

There will be a gradation in the image brightness but due to the effective image area differing from the differences in path length distance rather than as a direct result of the distance. Basically, the the edge of the image further away will be larger, reducing the illuminance per unit area.

Since they are electronic rather than optical what devices like the ImageAnyplace do is remap the image electronically to correct for the optical distortion. Say that you have a projector and move it off to the right, the image then becomes larger on the left and smaller on the right. What the device would do is make the right side the full projector resolution, map the center of the image to a smaller portion of that full resolution and the left side to an even smaller portion. This results in an image fits the screen. However, it also means that you are using less of the full projector imaging device as you move across, thus lower resolution and less brightness in areas where the image is 'squeezed' electronically to fit the physical conditions. I was very surprised at how acceptable the result can be but whether that is acceptable depends on the application.


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## Dreadpoet (May 5, 2009)

currently, downstage of the procenium is the only area where a speaker/performer can be on stage without having light cut across the face. The further back the projector...the worse. I am going to change course and put the projector closer to the cycwall...it think I can bring it about 12-14'feet closer...this will increase the vertical angle allowing performers to be midstage. Earlier, I was thinking that I could throw it from a horizontal angle and allow actor's/performers to work the majority of the stage...extreme SL (or SR depending on where I hung it) not included. The cable drop is not going to be fun, neither is getting maintenance's help on this.


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