Transparency problem!!

[tallvi]

Hi

I am having a problem with the alpha when i use mib-transparency.It is not giving me proper alpha.

can someone help me with how to go about it??

Cheers

tallvi

[Fugitive]

Have you enabled the pass custom alpha channel in render globals? plus you may also need to set your colorclip to RGB.

[elan]

how do you set u'r color clip to RGB? i overcame that problem by mapping a ramp tp the trans channel, but i don't understand u'r terms

[Fugitive]

Image Data type and colorclip attributes can be found in Mental Ray Render Globals > Framebuffer Tab > Primary Framebuffer...Pass custom alpha channel attribute can be found under Custom Entities

[tallvi]

I have done all that you proposed but still not getting the alpha properly.I am using Maya 7.0.Can u pls help?? Can u explain step by step how i go about it??

[elan]

Have you enabled the pass custom alpha channel in render globals? plus you may also need to set your colorclip to RGB.

Hi fugitive,
Thanks and finally i found where colorclip is. Though i've used gamma and data type, i never noticed color clip. Ok let me come to my doubt, problem was solved when i turned the color clip to RGB, but if i go by the mayahelp, they say "rgb should be used if the alpha channel is considered less important than preserving the RGB color and intensity. alpha mode is intended for alpha compositing, where the alpha channel is more important than the absolute color value to preserve correct transparencies". So i tried rendering with alpha in colorclip and i got a bad alpha(what comes with RAW mode), So how does alpha mode actually work?

1 more doubt, do v have to keep color clip to RAW if v r rendering a floating point image(32 bit)? (that's how i've done before). If so, what if i have a semi transparent surface & i need alpha for it(because alpha comes in RGB mode only)?

- Vimal. S

[mattMR]

hello,

for me I had trouble with alpha, when I tried to make a shadows passes for shave and a haicut... and I found a solution make my picture with the framebuffer at rgba 4x32(float) and my color clip at raw, and all customs shaders I used will be good in alpha, so you can try it also...

ps : custom alpha passtrough was enabled to work

>matt.

[elan]

Hi mattMR,
i think just for an alpha problem we don't have to waste a lot of render time rendering in 32 bits, the method that fugitive said is working fine. just change the colorclip to RGB. but somebody answer me why ALPHA to colorclip is not giving me good alpha?