View Full Version : MR transparency problem

09 September 2004, 02:36 PM
Hi, I'm creating an outdoorscene for a museumproject I'm working on. It has 2 spheres for the finalgather-bit, one for the backgroundimage (sky-image attached, no influence on the finalgather)and one for the control over the color used in the finalgather (little bit smaller, yellow). Works perfect, except one thing in the transparency of the trees in the background (just a plane with a transparant image, paint effects -> oakforest) :

Anyone has an idea how to fix this ?

09 September 2004, 08:04 PM
looks like this is a job for the raytype shader....

09 September 2004, 08:35 PM
What type of shader are you using for the trees? If it's anything other than a lambert, make sure it is a lambert, you could be getting spec highlights on the alpha. Also, change your Shadow Atenuation to 0.

09 September 2004, 10:15 PM
I had the same problem, took a photo acroos the street of a project I'm working on, now maybe I'm making the alpha channel incorrectly but all I did to get it working properly was to save the image as jpeg, then crop the sky fill with black, invert selection and fill that with white save that as a jpeg and save that as the mask.If anyone knows what I'm going wrong please let me know, I tried cropping the sky on a transparent layer and saving as a tiff with an alpha channel but it didnt work for some reason:scream:



09 September 2004, 01:24 PM
Only solution here, though not ideal, to take just one sphere for the finalgather rays and which has the airtexture. Project is coming along fine too....bless Maya's instancer haha !

Problems solved :

09 September 2004, 06:22 PM
if you are using Maya 6, try to use the IBL feature:shrug:

09 September 2004, 11:41 AM
The iblsolution didn't really work, after more then half an hour rendering I switched the render off, since it didn't even begin at the finalgather process yet.

The problem with MR is with transparency it seems. It doesn't allow tifs, psds or gifs to be used and pngs are rendered partially good (with/without alpha map for the transparency)(it renders some parts of the image correct with transparancy, but most is just nontransparant)

Really frustrating so far, again.

09 September 2004, 04:02 PM

To get beautifull outdoor illumination with 2 spheres, 1 for the background image and 1 for the finalgather color on all the objects, but without :

- weird black spots in your rendered image after the fg
- weird transparancy problems with imageplanes/objects with transparancy near the edge (where the spheres are).

This is what you need to do :

- create 2 spheres with 2 different lambert materials
- make sphere1 1 unit bigger then sphere2
- for sphere1, turn off 'primary visibility' / 'casts & receive shadows' in his render stats (attribute window)
- for sphere2, turn off 'casts & receive shadows' / 'visible in reflections & refractions'
- sphere1_lambert, set color to 0, incandescence to the desired color and diffuse to the desired value. This will control the final gather in your scene.
- sphere2_lambert, give the color the desired skytexture, set diffuse to 0 (very important to avoid the weird black spots) and turn up ambient color to the desired color. This will affect what you see in the background.

Cheerz, after 1 week of stress and frustration, it was almost just a matter of reverse the diffuse and ambient color values.

09 September 2004, 11:39 AM
And finally -> turn Scanline->openGL to On, helps to get rid of the transparency probs too!

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