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View Full Version : Shader: Glass is too hard!!


Andrei2k
05-05-2003, 12:00 PM
I am using maya renderer on glass and need it to not be black-like in my scene.....ambience turned up makes it look less real and the envchrome tweaking has got me nowhere....plus the whole 'grid' on env chrome i dont particularly like and want to use pics but where i put them in sky , floor, horizon etc doesnt do much.


Most importantly i need it to look goon in the following scene no matter what happens. Please help I've been struggling for months......

Ronald
05-05-2003, 12:51 PM
first of all, dont use the envchrome texutre ! use an image instead projected on a sphere (pe. use ur bg-image). your glass looks too dark. get lost of the diffuseamount and set it to 0. refraction should be 1.33. you can set your transparency so it get a little (just a tiny bit) blue or green. try to use mentalray insted of the mayarenderer!

ronny

alexx
05-05-2003, 01:28 PM
be sure to have a propper environment..
otherwise the renderer will reflect/refract the black from the background.

if needed, create a sphere larger than everything and map your background image to it.
that should do the trick

cheers

alexx

Andrei2k
05-05-2003, 01:49 PM
I've tried the mental ray render but this thread is a replica of my problem as well that i can't fix......

http://www.cgtalk.com/showthread.php?s=&threadid=58053

mapping the bg to a sphere will only work if using mental ray obviously but will those other settings help the maya renderer? if the black inside mentalray issue can be fixed in the thread mentioned.ill be more than happy to use MR.

alexx
05-05-2003, 02:00 PM
ah ja.. one thing:
be sure your image plane has
"visible in reflection and visible in refraction"
turned on..

would be best to cam-project some of the objects like the tea pot and so, to get realistic reflections..

quick test:
http://bigott.gmxhome.de/pics/glass.JPG

cheers

alexx

scene file if you like:
5.0 scene (http://bigott.gmxhome.de/pics/glass.mb )

alexx
05-05-2003, 02:13 PM
same with mental renderer (you need high reflection ray amount to get rid of the black lines)

http://bigott.gmxhome.de/pics/mentalGlass.JPG

Andrei2k
05-05-2003, 02:58 PM
You are amazing!!! Man oh man my new best friend! so all the setting i can just check in the file for both......i see....so the rays you had to set to 8 Man where can I get more of the lowdown about the way light works versus what all these million render properties do as examples....I watched a mental ray video but it only taught me like general ino win min.max and photons not increasing rays to get rid of black in middle of glass......there isnt a non 'Einstein read' book out there is there? Like how did you learn the nitty gritty.....practice or more? Sorry with all the q's but I'm sure others like in that thread would be impressed by your wisdom also because im sure im not alone to realistic rendering problems even though ive used maya for 3 years.....Thanks a lot you saved my life.:beer:

alexx
05-05-2003, 03:14 PM
emm.. thanx :)

well: no.. the mental ray settings are not in that file i think..

but it was nothing but changing the renderer to mental and increasing the reflection samples.

concerning my "wisdom": that is mostly trial and error..
i might have some experience after about 5 years of maya now as a TD for a small bunch of ppl (finding where problems are and so on) but mostly i did all that by clicking some stuff and seeing what the render becomes like.. (naja.. not only but quite a huge amount)
i never really dealt with that glass issue before some hours ago to be honest.
and i really think there is something strange going on in mental ray.. but i am not really familiar with that one - so it might be as well that i am missing some fundamentals there :)

:beer:

alexx


edit: the file link above now directs to a file with both maya and mental settings in

Andrei2k
05-05-2003, 09:27 PM
I am comping the glass into After Effects and the problem is that I cant render it right without the image plane on and I dont want the image plane to render.....when the image plane is off the glass look weird when comped because the alpha is just white or 1 all around.....can i retain the alpha transparency and the overall look with just rendering the glass?

Again sorry about this but its the last issue that arose.......its the last I promise :love:

Ronald
05-06-2003, 08:06 AM
you can render a seperate matte-passe by just getting rid of the image plane and render ur glass with a surface-shader on it (renders faster and u dont need any transparency in your alpha). then just get into compositing and use this as your alpha!

greetings

ronny

alexx
05-06-2003, 10:43 AM
since you need the refractions of the backplane you have to render it.
but you can turn off the primary visibility of it.
like that you will get the glass with the right reflections/refractions but the correct alpha (of course with no transparency in the glass itself..)

be sure, your image plane has the right settings (frame aspect). otherwise the render will not match the background perfectly in comp.

cheers

alexx

Andrei2k
05-07-2003, 04:38 AM
Thank you both for the info and Ronald you are the man with the plan that shader trick worked perfectly thanks!!!

This is the most helpful glass thread ever and it will go into history books as so :buttrock:

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