View Full Version : Rendered plate image not as clear as original

01-20-2007, 03:43 PM

I've got a basic vfx shot set up to render with a background image, as well as some objects with the same for a front projection to catch shadow, bounce, etc. The image that I am using comes from a video shot of the scene background.

For some reason, when I render a frame in LW, the background and the front projections are not as clear as the original plate bitmap (it's a building and the mortar lines are distinct, and the window bars and blinds show evidence of losses/slight blur).

Is there anyway to correct this? Is it because of an antialiasing effect the render has upon bitmaps? I've made sure that I turned off filtering and antialiasing and blurring in the render options.

I'm an amateur, so speak slowly.


01-21-2007, 09:49 AM
Be sure to turn off Mip Mapping in either the Image Editor (F6) or Surface Editor (F5). Mip Mapping is a method of reducing moire patterns in textures when they're farther from the camera, so they get blurrier in the distance. For front projection, you don't want this to happen, so turn it off.


01-21-2007, 10:23 PM
Thanks. I tried it and it looks pretty good (it was set on high, so I think this may have given me a marginal improvement), but I'm still getting some losses in some detail. For example, some window bars seem to "disappear" or become "dotted" after a render, even when just the background is rendered. I did notice, if this helps, that if I took the plate shot to photoshop, doubled its resolution, saved it and the used that to render the scene, some of those "bars" and other details start to show up again. I don't know if this is what I want to do or not if I'm losing something I don't know about yet (and won't find out until the end of a 23 hour render).


01-22-2007, 10:16 AM
Make sure your camera resolution matches the background plate resolution. Otherwise, you'll lose detail as LW tries to stretch or shrink the BG image to fit.

Here's an Image Filter plug-in I wrote a while ago which moves the background image into the final image based upon the (inverted) Alpha channel. Basically a live composite, which I used all the time in front-projection work. Really helped me adjust the luminosity, diffusion, etc. of the front-projection Shadow Density surfaces to get more background detail in the projected shadows without having to do the compositing pass externally.

Note that the plug-in won't even try to move a BG image which is different resolution than the camera. You'll get an error if you try.

Since the plug-in moves the BG image pixel-by-pixel without any modification (other than alpha blending), if you continue losing detail I'd guess you're losing it in your compositing app rather than LW.