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Advice for projecting an HD image onto a CIRCULAR screen

post #1 of 6
Thread Starter 
Hi everyone and thanks for the help,


Im making a video projection for a music festival. It is to be projected onto a big circle screen. the circle will be 12 feet across...


My project is done in after effects. I've rendered out the video in the following format
-HDTV 1920 x 1080
-16:9 Aspect Ratio


I have also added a circle mask which lies bang on in the center of the video.



My question basically is, will this circle fit perfectly onto the 12foot across screen? I will be projecting using an HD projector, but is there any kind of math/calculations I need to make to ensure that my crop circle that I apply to the video actually matches the screen circle?



Sorry for sounding like an idiot, its my first ever projection project. I'm a graphic artist but I have no idea about hardware like projectors... smile.gif



David
post #2 of 6
Since you asked this in the CRT projectors forum, are you using a CRT projector (as opposed to a more portable digital LCD or DLP projector)? If you are, there are geometry adjustments that can easily be made. to compensate for the curvature of the screen. If it's a digital projector, things could be a bit trickier and depend more on the specific model of projector you have.
post #3 of 6
Quote:
My question basically is, will this circle fit perfectly onto the 12foot across screen?

that would depend on the zoom lens and position of the projector.
post #4 of 6
Thread Starter 
thanks for the reply.

I think maybe i worded it all wrong. The circle screen is not curved. its a flat screen like any projector screen only shaped like a circle instead of rectangular. The reason why I'm confused about whether the image will fit is because of aspect ratios? But I think I'm just being stupid now, because surely I just have to calculate the aspect ratio of the circle screen and see that it matches that of my video circle...?


thanks again.
post #5 of 6
Quote:
Originally Posted by liebermand View Post

thanks for the reply.
I think maybe i worded it all wrong. The circle screen is not curved. its a flat screen like any projector screen only shaped like a circle instead of rectangular. The reason why I'm confused about whether the image will fit is because of aspect ratios? But I think I'm just being stupid now, because surely I just have to calculate the aspect ratio of the circle screen and see that it matches that of my video circle...?
thanks again.

Okay, I see what you're saying. You'll want to fill the entire circle? Aspect ratio is still somewhat relevant: measure the maximum width and the maximum height (if it's a true circle and not an oval, they will be the same). Since the projector projects a rectangle, you'll have some wasted projected "area" not projecting onto the circle but you can adjust that in your video source if need be.
post #6 of 6
Thread Starter 
yep thats what i thought...


the 'dead' area in my projection is anything outside the the circle crop that i applied to the video i made. the circle crop is a uniform circle so i take it all that's left to do is find the correct distance between the projector and the screen right?
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