PDA

View Full Version : Video Resolution



spaceball
06-14-2009, 09:16 PM
Hi I have just been making some sets for a client.
Firstly I'd like to compliment all at Newtek on what a great system you've built!
The sets are looking good, but since I don't have a Tricaster at home I can only check my work during studio downtime, so far there is just one issue - it's not really a problem, just trying to get the best results out of the system..

Here's what we noticed:
When you insert a newsreader/actor etc using the "Keyhole matte" checkbox i.e. mapping the live video 1 to 1 over the top of the bg set the picture is nice and sharp.

When you drop the actor in using the the "warp input shader" on a poly the video seems softer - a little bit blurred, definition loss in hair etc.

I'm guessing this is because the video is being scaled onto a polygon in the tricaster using opngl(?) so there is some stretching/mipmapping/bilinear interpretation etc...

Any tips for ensuring the video quality is at its best for wide, medium and close up shots?

This came to light because the client wanted the newsreader to be able to walk onto the set and then sit down at the newsdesk - when I made the LiveInput polygon big enough to allow this the video quality suffered. When I made the Polygon "man sized" again quality was nearly as good as the direct video feed. (But not perfect)

Hope some of this makes sense :)

billmi
06-16-2009, 11:25 AM
Yep, the video has to have processing done to eliminate worse artifacts that would result from the scaling/warping (aliasing, loss of single line/pixel details.) That's just a fact of life.

joseburgos
06-16-2009, 09:18 PM
Indeed.
Also just to be sure, never size the LiveSet textured object larger than full screen in camera. Rule is, if it will be full screen, make it keyhole. After that, must be less than 100% of the screen to look good.

As to walking on to the set and then walking behind the desk, you may try a trick I worked on in another thread;
http://www.newtek.com/forums/showthread.php?t=86444
What you would do is create a wide or extreme shot with the liveset input video plane next to the desk, say to the left of the desk. The scale would be small to match the extreme shot but make sure it is large enough to give the actor enough room to walk a few steps before he gets to the desk. This extreme shot will have the live video plane rotated 180 degrees. Now make the next shot a med and use keyhole for it. This will have the input video plane full screen and do the scaling in camera.
Now if you want the actor to walk on the set from the left, have him walk on the green screen from the right. He can waive and say hello and begin to walk behind the desk. Have him walk off the green screen. Now switch to the med shot as soon as the actor walks off the green screen of camera frame and then he walks back in. He really does not need to pause and should not because the switch to med will be exactly when the actor goes off frame. Now as he walks back on from left to right, he will be in the LiveSet from left to right. The trick is since the extreme shot has the video plane 180 degrees or inverted, the actor walks right to left on green screen but on the LiveSet he walks left to right. Then walks off camera frame and right back in and the new shot has the video plane normal so he walks left to right but since you changed the LiveSet shot, he just seems to have kept walking from left to right till he was behind the desk.
If this is a stand-up desk, you can use one green screen to fake a longer one with this trick.
Now if you need a chair type desk, you will need two green screens with the 2nd having the chair. Unless it's a small stool and somehow you can occlude it with something on the sets extreme shot.

Anyway my point is you can get around this with some planning. It would look natural for the person to be on camera and walk towards a desk and then the camera change and the person to walk into frame and sit behind the desk. No one would know the better.

Good luck,

billmi
06-17-2009, 12:59 PM
Now if you need a chair type desk, you will need two green screens with the 2nd having the chair. Unless it's a small stool and somehow you can occlude it with something on the sets extreme shot.

As long as the chair doesn't need to be visible in the desk shot (like a stool) you can paint it to match your green screen, or carefully drape it so that it keys out of the walking shot along with the screen.