Im currently doing an arch vis scene. I often find I have problems with knowing how bright a particular texture should be for the setup I have created.
I normally start off with a vraysun/sky. Then i set the iso to 200, F-stop to 16 and then the shutter speed to something like 250. I then set a basic white material with RGB value of 157. Is this white values correct for that kind of setup ?
Then I would like to know what RGB values would be for materials such as grass, concrete wall etc so that I can stop rendering so many test scenes and have a more flowing type of process.
Is there a list out there that says, white in Vray with a vraycamera should be set to RGB 157, grass RGB should be near values…
I think a book on color theory would help you, it helped me.
I usually set up my scenes with lights and a camera, place a box with a white material, and expose the camera until my float is around 1,1,1. I turn off clamping and I am in linear space for this.
I normally start off with a vraysun/sky. Then i set the iso to 200, F-stop to 16 and then the shutter speed to something like 250. I then set a basic white material with RGB value of 157. Is this white values correct for that kind of setup ?
I think you on the right lines with this. If you follow your logic through then you should set the ‘RGB Level’ for bitamps to about 0.61 (157/255). You should also limit the RGB values of other materials like procedurals etc. to below 157 as well.
I did a bit of reading about this a while ago. I remember reading that fresh snow is one of the most reflective diffuse materials and that reflects about 80% of light. So you’re probably not far of with a value of 61% for white paint. I settled on a value of RGB 200 for white paint. I know it’s not physically accurate but it makes lighting interiors easier with fewer dark corners. I suppose it depends on what your final output is for. Most clients want interior renders to be brighter that your average interior photogragh.
Thanks for the advice. At least I know my process isnt too far off. I may up my white values for future scenes as Ive read a number of people using around 200rgb for white…see how that works out.
Yeah, I think a book would probably help too. Im still reading vray, the complete guide…
Interesting topic Steve. I have always made sure my white materials were not 100% white, but didnt realise the theory was to go as low as rgb200 or even rgb157!
to my knowledge rgb 220 (some say around 230) is more or less the correct “white” value. / this is the physical measured white of a white sheat of paper. used very often time in realworld to get the white point.
i recommend also reading info about photography. 99% is also true for vray rendering.
Its obvious that no-one seems to use the same white value and still get satisfactory results. I think I will go with the knowledge that 80% of light is reflected from a white surface and so I guess RGB 176 will be my new white value from now on.
I wonder if that is based on a white high gloss surface or a matt white surface
I wonder if that is based on a white high gloss surface or a matt white surface
Reflectivity (or albedo) values are normally done using a totally matt surface, I think they grind the material to a very fine powder before measuring. I think you can get much higher values from a gloss surface.
I usualy put a grey128 material on all objects and make lighting. I try to get the medium grey in render out put too. Then I put 225grey for white and increase lighting only a bit. And then try to put proportional values for all materials in between.
I am sometimes confused about physical accuracy. The reflactance value is also how much light is bounced in real life- am I wrong?
So then do we need to put reflective materials (maybe even fake reflective values) so that light bounces off more and get brighter renders?
I can never decide which approach is better. And honestly I really feel mixed up. So I always give up about physical accuracy. But I do believe that it would be a nice starting point for each scene if I can be able to understand the logic.
If you use your method dont you encounter problems with exposure ? If you have the exposure set so that the rgb values are around 128, isnt your sky very dark ? (If using vraycam exposure). If you have dont affect background (when I tried), the background was pure white and the building looked very gray still even if I put the sun multiplier up to 1.4)
