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williamb
01-13-2007, 03:19 AM
Hi
How can I have an image world environment…so as to get reflections coming of an object (logo) and keep a alpha transparent background?

What I have is a logo…and I have filmed a scene painting a house. I want the logo to reflect that scene…works wonderful when I use image world…but that gives me a background image.

The logical solution is to just put in the background video I tend to use…but for some reason…it flickers when I render.

All set to even field. Background image is RTV uncompressed. I render even fields (PAL) and yet it flickers! Tried rending RTV…AVI..AVI newtek25

Please help…I should have this finished by now…thanks

williamb
01-13-2007, 03:31 AM
By the way...it sort of works if i project the image from a spot light...but maybe not as desirible.

Lightwolf
01-13-2007, 09:25 AM
Just load in a black background image (any size, 16x16 pixels will do). This will overwrite the image probe.

Cheers,
Mike

avkills
01-13-2007, 10:39 AM
Just load in a black background image (any size, 16x16 pixels will do). This will overwrite the image probe.

Cheers,
Mike

Will that still give him an Alpha channel?

I was going to suggest just using a spherical reflection image in the surface properties. Maybe use a flat plane and have it unseen by the camera would work also.

-mark

Lightwolf
01-13-2007, 10:47 AM
Will that still give him an Alpha channel?

Yes, none of the background "items" (gradient backdrop, backdrop plugins like Skytracer, Image World) actually change the alpha. However, since the RGB is usually pre-multiplied, you get problems when compositing a rendered image with an (transparent alpha) RGB of anything but black.


I was going to suggest just using a spherical reflection image in the surface properties. Maybe use a flat plane and have it unseen by the camera would work also.

Both would work. The advantage with using a central location such as the backdrop is that you can swap out the reflection image on a per scene basis, without needing to save different objects (one per reflection map used).

There's many ways to skin a cat as they say ;)

Cheers,
Mike

avkills
01-13-2007, 10:49 AM
Good points Lightwolf. Good to know about the background items not messing with the alpha. Thank you for the information on that titbit. :D

-mark

Lightwolf
01-13-2007, 10:52 AM
Good points Lightwolf. Good to know about the background items not messing with the alpha. Thank you for the information on that titbit. :D

Anytime, my pleasure.

Cheers,
Mike

williamb
01-15-2007, 09:26 AM
Hey thanks guys
Had a good play around all works well...used the surface options as i only had one surface...works perfectly.
Cheers
William