vray self illum and fog colour.

[super gnu]

im trying to get a nice glowy soft look to a load of geometry.

i can get the soft look with 100%refractive with a fog colour in there...


i can get a glowy effect with self illum..

HOWEVER, it seems that the self illum makes all the geometry glow, irrespective of wether it is transparent or not, so i lose the soft faded edges when i add self illum.

is there any way to make the fog colour itself self-illuminated?

[vlado]

is there any way to make the fog colour itself self-illuminated?

Not for the moment, but I'll make a note for it. It might be possible to use VRayEnvironmentFog confined to within that object - without any illumination or anything, just to use the emission color.

Best regards,
Vlado

[super gnu]

ye i tried that.. unfortunately its about 60 objects (a whole tower block) with all sorts of gaps and single sided objects in it. ive tried assigning the whole lot as a fog gizmo, but i get an unhandled exception and dump to desktop.

it would be very nice to be able to do this effect with the fog colour.. closest i can get to the effect im after is to use the alpha channel as a mask in post.. it has the correct soft edges and i can use it to mask a bright colour.. however in this case i wish to have many materials of different colours and transparencies overlaid, so a right PITA.

[vlado]

Right; it's definitely something that we need to look into.

Best regards,
Vlado

[super gnu]

great.. sounds positive.

on a related note, is it theoretically possible to have a vray fog map? like falloff, but doing what the fog colour does... i often use falloff to try to get these soft edges, but it only works properly on spheres!

[vlado]

on a related note, is it theoretically possible to have a vray fog map? like falloff, but doing what the fog colour does... i often use falloff to try to get these soft edges, but it only works properly on spheres!

Now that you mention it, you can actually use VRayDirt for a sort of a similar effect. Put VRayDirt in the self-illumination slot, check "invert normals", set the distribution to a very high value (like 100) and set the Falloff to 1.0. You may need to increase the radius a bit to get what you need.

Best regards,
Vlado

[super gnu]

ive been trying that, but have not been able to get a decent result.. maybe i should play more.

[super gnu]

ne thing ive noticed.. in the vfb, if i have say a refractive material with a dark red fog colour and self illum, the alpha channel is the opposite colour.. i.e. greeny blue. isnt the alpha supposed to be greyscale?

[vlado]

ne thing ive noticed.. in the vfb, if i have say a refractive material with a dark red fog colour and self illum, the alpha channel is the opposite colour.. i.e. greeny blue. isnt the alpha supposed to be greyscale?

Nope, the alpha transparency is a color value (otherwise you can't really composite colored objects properly). The greyscale thing I suppose has stayed on from ancient times when people tried to save memory and nobody thought color transparency was really that important.

Best regards,
Vlado

[super gnu]

you know i never considered that. so the alpha channel in png's etc is an rgb image?

[vlado]

you know i never considered that. so the alpha channel in png's etc is an rgb image?

I do not know of any format that stores the alpha as proper RGB (except OpenEXR where it can be stored as a separate channel). V-Ray converts the color to a greyscale value in the end for the sake of compatibility before writing the image. But V-Ray still generates it correctly, for the distant future day when it might be needed

Best regards,
Vlado