Maybe I should have qualified my statements and said that AO is more physically-based than alpha transparency
:-) Or, maybe I was thinking that ambient light ceases to be ambient when it passes through a transmitter/reflector. It should become something like "ambient transmission" or "ambient reflection". On Mon, Apr 23, 2012 at 3:51 PM, François T. <francoistarl...@gmail.com> wrote: > well that's because AO is not physically correct, not because you are not > applying it correctly or not. > even ambiant light would get transformation through glasses, which "basic" > AO won't take in consideration. But it seems that AO cycle is a bit > different according to Bretch. > yet most of the time, people do not use AO like it should be though. IMO AO > should be used as follow : (AO*ambiantLight)+otherLights+diffuse,.... > But even like that, it wouldn't be so correct, because ambiant light going > through glasses in real life should get transform. > > my 2 cents again > > 2012/4/23 Jason Wilkins <jason.a.wilk...@gmail.com> > >> I would tend to agree with François, ambient occlusion is function of >> 3-space where ao(x,y,z) is the proportion of the solid angle around >> that point that contains geometry that blocks ambient light. All >> geometry, even transparent geometry, blocks ambient light. So, if you >> are seeing darkening on a refracting or reflecting surface it is >> because you are not combining ambient occlusion correctly, not because >> the AO has been calculated incorrectly. A refracting or reflecting >> object really does block ambient light 100% and only lights other >> surfaces through caustics (or itself through transmission). >> >> If a surface is partially refractive or reflective, but also diffuse, >> then only the diffuse part should be affected by AO. >> >> If it is because the object has alpha transparency then that is not a >> physically based kind of lighting and then there really isn't a >> "correct" answer. People might give different answers if you asked >> them should the object give AO to itself vs contributing to other >> objects in the scene. From Brecht's explanation it sounds like Cycles >> just ignores this kind of transparency for global illumination >> purposes. >> >> On Sun, Apr 22, 2012 at 5:21 PM, Brecht Van Lommel >> <brechtvanlom...@pandora.be> wrote: >> > Augustin is right, it works, but only for the Transparent BSDF. In >> > Cycles, Transparent is defined to work as, "render as if there was no >> > geometry there", which also affects AO and shadow rays. >> > >> > The case could be made that the Glass BSDF should also work this way >> > for AO rays, but it gets fuzzy then, where depending on the particular >> > settings of a BSDF it may seem a good/bad idea to make it transparent. >> > Right now there's a clear and consistent rule at least, and you can >> > control it with the light path node. >> > >> > Brecht. >> > >> > On Sun, Apr 22, 2012 at 11:32 PM, François T. <francoistarl...@gmail.com> >> wrote: >> >> As AO is geometry based, as far as I know, it is not supposed to make >> >> difference on its transparency, as at least the basic algorithm only >> check >> >> for mesh data, but not the material. >> >> >> >> >> >> 2012/4/22 Agustin Benavidez <agustinbenavi...@gmail.com> >> >> >> >>> I am pretty sure it does work with transparent BSDF, and not with >> caustics >> >>> i.e. using glass bsdf , so if you are using glass bsdf, use light path >> node >> >>> to switch to transparent bsdf at least for shadow/diffuse rays or >> whatever >> >>> ray you need. >> >>> Cheers >> >>> >> >>> >> >>> 2012/4/22 Tobias Oelgarte <tobias.oelga...@googlemail.com> >> >>> >> >>> > I made some experiments with Cycles today and I noticed that AO sees >> all >> >>> > faces as opaque, like the internal Renderer did. That means that a >> face >> >>> > with glass material (entirely or nearly entirely transparent) will be >> >>> > dark (itself) at parts close to other geometry. Should AO not have >> much >> >>> > less impact on such surfaces? Otherwise it can be hardly combined >> with >> >>> > transparent materials. >> >>> > >> >>> > Do you see room for improvement or should it stay this way? >> >>> > >> >>> > Greetings from >> >>> > Tobias Oelgarte >> >>> > _______________________________________________ >> >>> > Bf-committers mailing list >> >>> > Bf-committers@blender.org >> >>> > http://lists.blender.org/mailman/listinfo/bf-committers >> >>> > >> >>> _______________________________________________ >> >>> Bf-committers mailing list >> >>> Bf-committers@blender.org >> >>> http://lists.blender.org/mailman/listinfo/bf-committers >> >>> >> >> >> >> >> >> >> >> -- >> >> ____________________ >> >> François Tarlier >> >> www.francois-tarlier.com >> >> www.linkedin.com/in/francoistarlier >> >> _______________________________________________ >> >> Bf-committers mailing list >> >> Bf-committers@blender.org >> >> http://lists.blender.org/mailman/listinfo/bf-committers >> > _______________________________________________ >> > Bf-committers mailing list >> > Bf-committers@blender.org >> > http://lists.blender.org/mailman/listinfo/bf-committers >> _______________________________________________ >> Bf-committers mailing list >> Bf-committers@blender.org >> http://lists.blender.org/mailman/listinfo/bf-committers >> > > > > -- > ____________________ > François Tarlier > www.francois-tarlier.com > www.linkedin.com/in/francoistarlier > _______________________________________________ > Bf-committers mailing list > Bf-committers@blender.org > http://lists.blender.org/mailman/listinfo/bf-committers _______________________________________________ Bf-committers mailing list Bf-committers@blender.org http://lists.blender.org/mailman/listinfo/bf-committers