nisus Posted August 23, 2004 Share Posted August 23, 2004 Hi All, I have made a glass material like this: - mental ray material - surface: glass (lume) - shadow: glass (lume) When I render without caustics, the material is ok (transparant shadows), but when i turn on caustics the glass is transparant, but the shadow is not. I have added several shaders in the photon slot, but could not solve this problem. Anyone got a clue how to solve this? rgds nisus Link to comment Share on other sites More sharing options...
William Alexander Posted August 24, 2004 Share Posted August 24, 2004 Nisus, Could you post an image. What you describe almosts sounds like the caustic photons are getting trapped, or die before they exit the glass materials mesh. What are the the settings-ie decay, caustic radius, max trace depth settings. Upping the refactions (trace depth) may help and making sure the "sum" is equal to the reflection/refraction total. Did you check ingnore normals in the Lume Glass settings, and is the I.O.R value correct? Is mental ray render dialog saying anything wierd in reference to storing caustic photons, like x photons stored but no shader to release to? All I can think of at the moment, short of some coplaner faces maybe trapping photons. Cheers WDA Link to comment Share on other sites More sharing options...
alaburb Posted August 24, 2004 Share Posted August 24, 2004 First, you should check that in the properties of the glass you have 'generate caustics' switched on. Easy to forget... Next, cruise over to CGTalk and research the MRay shader forum. Its a gold mine. Jeff sorted me out when I had a similar problem with Mental Ray glass.... http://www.cgtalk.com/showthread.php?t=104578&page=85&pp=15 Link to comment Share on other sites More sharing options...
nisus Posted August 25, 2004 Author Share Posted August 25, 2004 Hi all, Tnx for the replies. wda: all settings are default, except the decay that i've put to 2. ray depth is set to 6 / 6 / 12... IOR correc, gonna check the normal thing in the lume glass... alaburb: all objects generate and receive caustics ;-) My main problem is what shader to place in the photon shader map slot... I've tried both the photon (base) and the transmat photon, but honestly... I have no clue what they do... I've upped the energy for now and have 'some light' coming through the glass for now... doesn't look like caustics though... rgds nisus Link to comment Share on other sites More sharing options...
alaburb Posted August 26, 2004 Share Posted August 26, 2004 Just checking.... Theoretically there should be no difference btwn Mental Ray material and simply using the Mental Ray connections rollout at the bottom of a standard materials parameters. However, I have only been able to get results with the basic photon shader if I put it into the photon slot of a standard material (likewise, unlock the surface and sadow maps here and apply glass lume for both - as you would for the MR material). Anothehr thing to remember is that the RGB values in the BasicPhoton->Transparency should be set at 100 each. Moving the sliders will only allow you to max it at 1 (which still looks white btw) you will have to type in the value. Hope this helps. I am sorry, but I am still not very clear on this stuff myself.... If you post the scene we can probably help more... Link to comment Share on other sites More sharing options...
enigma Posted June 29, 2005 Share Posted June 29, 2005 try these...Mental ray material....Surface: place Dielectric material 3dsmax(instance to photon slot) or u can simply place glass lume on the surface. Shadow slot select shadow transparency. I'm pretty sure it'll work out well with caustics. Link to comment Share on other sites More sharing options...
vizwhiz Posted June 29, 2005 Share Posted June 29, 2005 Nisus and All i put up a blurb about starting a Mental Ray forum, yes/no? so That all of This useful Info could be somewhat collected into 1x place just an Idea i am reading ALL MR messages doing 2006 VIZ Tuts at nite i am just not getting The desired results yet That are possible still learning, lurking in The shadows Till i can get something To Post Thanks mental Randy Link to comment Share on other sites More sharing options...
Thox Posted August 2, 2005 Share Posted August 2, 2005 I know this is an old thread, but I recently had the same problem, transparent glass, but no transparent shadows. I looked here and on the CGtalk forum for a solution and tried various methods. I was just about to turn off caustics and use Jeff Pattersons method http://forums.cgsociety.org/showpost.php?p=1506191&postcount=1271 and then noticed a little check box in caustics "Opaque Shadows when Caustics are Enabled" which was checked. Unchecked this and it worked a treat. Just thought I would share. Thox Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now