Projector question

[orwell84]

I am trying to build a curved screen setup with 2 projectors (Optoma es525st). I am using immersive display lite 2 to warp the visuals. The screen covers about 130 degrees over a 5 foot radius. I am happy with the coverage and positioning of the image and the warping software works well. The image though is very washed out and lacking in contrast no matter how I adjust it. The projectors should be in the ballpark for brightness and contrast ratio. I am hoping it is my temporary screen, which is made from cheap shower curtain liners that is resulting in my poor image and not something that I can't fix. Are there any good sources of information for adjusting projector image quality?

Any help would be appreciated.

Thanks.

[blueskydriver]

Hello Orwell,

First, read this information about screens here:

http://www.mycockpit.org/forums/show...803#post125803

The likely problem is that your shower curtain does not match the gain of the projectors. Go to the Optoma website to read all about your model and what the required gain values are. Also, are these new projectors you purchased or used? How many hours does the bulbs on the projectors have, as this will affect brightness/contrast? Are you in a darkened room or with other light sources on?

Finally, I'd suggest you get a new screen right away because you might spend wasted time adjusting for the shower curtain liner, and then go through this all over again when you do get a projector screen...

Best Regards,

BSD

[Mike.Powell]

I am trying to build a curved screen setup with 2 projectors (Optoma es525st). I am using immersive display lite 2 to warp the visuals. The screen covers about 130 degrees over a 5 foot radius. I am happy with the coverage and positioning of the image and the warping software works well. The image though is very washed out and lacking in contrast no matter how I adjust it. The projectors should be in the ballpark for brightness and contrast ratio. I am hoping it is my temporary screen, which is made from cheap shower curtain liners that is resulting in my poor image and not something that I can't fix. Are there any good sources of information for adjusting projector image quality?

Any help would be appreciated.

Thanks.

I think there are three major contrast killers in your setup.

A portion of the light hitting the screens is reflected into the room which diffuses and reflects a portion back onto the screens. This is often controlled with dark room paint and furnishings.

A portion of the projected light passes through the screen and is reflected by the room back onto the screen. Control this by replacing the screen with a screen which is not transluscent, or by hanging black fabric behind it.

Some of the light leaving screen A hits screen B and visa-versa. This can be somewhat controlled by using special screens, limiting the viewing position, and careful projector positioning. Pragmatically, we just live with the situation as the fix is too expensive.

"Contrast enhancing" screens can be used in some situations, but do not work in all cases. They are most effective when it's not possible to control secondary reflections from the room. Used inappropriately, they simply make the image darker with no improvment in contrast.

Da-Lite Screen company put a number of articles about screen performance and use on their website. It's a lot of material to wade through, but it does provide good information. http://www.da-lite.com/education/ Look at the "Angles of Reflections" and Angles of View" articles.

[orwell84]

Thanks very much for your help. I think you are right about my setup. I need to reduce the amount of light reflected back. My space is very small with white walls. Putting black clothe behind the curttain helped somewhat, but I need to modify everything bit by bit to reduce this. Building a real curved screen will help. Thanks again for pointing me in the right direction. I will post back about what works. This hobby send you down so many rabbit holes. at least it is fun and interesting.

[orwell84]

I was also wondering about the role of projector placement. When I first tried this set up, I had the projectors close together, toward the center of the sim pointed outward. I then moved them apart toward the side of the cockpit because it gave me larger coverage and they no longer interefered with the roof of the cockpit. They are pointed in more of a parallel direction. I'm not sure if this matters in term of image quality or not. I should include some pictures or drawings. I guess my next question is whether there are any specific guidelines in terms of projector placement with multiple projector setup. I could test it out, but trial and error with moving projectors around is real grunt work.


I was also considering screen size. Would my light problem be reduced if I used a smaller screen size ( no more than can be seen from the cockpit) with blacklothe bordering it. Why produce an image larger than can be seen from the cockpit if all it does is wash out the image with extra light? Also some other observations:
-the image looked better when flying at dawn with increased cloud cover.
-close up objects look fine, it is distant landscape that is had to see.

I think the projectors themselves work ok. One is about 1 year old with not that many hours on th bulb. The other is a refurb with a new bulb. Side by side image quality, brightness, etc. is identical. I would think if there was an issue with either one, these factors would differ.

Thanks again for the kind help. At the very least I will be able to provide some feedback on using a curved screen in a really small space (9 feet, 9 inches, with a screen radius just enough to fit in this space).

Thanks again.

[Aaron]

Hi Orwel,

There are not rules in the way you positioning the projectors. That something to do acording with your setup, short throw, cabin high, roof high, radius, shadows, etc.

The closer to the screen, the smaller the image size is and the more brightness and by the way contrast. The "grid" of the DLP's is smaller or invisible at all if the screen size is not as huge. Where you need the largest posible image, its in the lateral views because you can view below the screen through the windows frame.

[orwell84]

Ok, I am getting somewhere. I built my curved screen which surprisingly didn't produce much better results than the shower curtain. I quit for awhile and did some more research based on your suggestions tutorials, etc. I realized I had made some mistakes and missed some important things that should have been obvious. Thanks for helping me figure this out. I will write down what I learned in case someone else comes across this thread.

1. Projectors should be aligned so that the lense is pointed toward the center of the screen as close to perpendicular as possible. My projectors were hitting the screen at a very steep angle resulting in an image that went from small and bright on one side to large and washed out on the other.

2. Planning the setup on paper or in a design program makes a huge difference (I used Turbocad). I came up with a design that I never would have come up with otherwise and I was pleasantly surprised to see it work. I didn't think it would but measurements don't lie.

3. Dividing your curved screen up in your design as if it was made up of flat panels gives you a good starting point for where the projectors should go, hitting these panels as straight on and centred as possible.

4. The lense is the reference point and not the projector mount unless the lense is right in the center of the projector body.

So now my projectors are set up so that they project 2 roughly square portions of light of equal size overlapping slightly at the centerpoint. I haven't even had the time to test out the image, but I am certain it's the best I can do with what I have to work with and that image quality will improve. I will certainly let you know how it goes.

Thanks again for helping me figure this out.