vray.info
chaos group forum
Reflective Values
posted by Jon Reynolds
archived on 11.3.2003
pure aluminum /polished/ 80 - 87 %
polished aluminum 65 - 75 %
matte aluminum 55 - 75 %
aluminum painting 55 - 65 %
steel 25 - 30 %
INOX 80-90%
polished chrome 60 - 70 %
high polished copper 60 - 70 %
high polished brass 70 - 75 %
light oak /polished/ 25 - 35 %
dark oak /polished/ 10 - 15 %
wood chipboard 25 - 40%
white paper 70 - 80 %
granite 20 - 25 %
lime stone 35 - 55 %
polished marble 30 - 70 % (depending on color)
light stucco 40 - 45 %
dark stucco (rough) 15 - 25 %
concrete /rough/ 20 - 30 %
bricks red/new 10 - 15 %
glass 5 - 10 %
silver mirror 80 - 88 %
high polished mirror 92 - 95 %
white tiles 75 - 80 %
white enamel 65 - 75 %
white lacquer 80 - 85 %
Reflections/refractions 101
posted by Flipside
archived on 17.1.2004
Ok, some clarification about reflections/refractions:
Reflection color: it replaces a number for the amount of reflection. White is fully reflective, black is non reflective at all. By using color instead of greyscale you get colored reflections (of course).
Fresnel: polygons facing the viewpoint will reflect less than polygons facing more away from the viewpoint. For example on a sphere, the edges will reflect more than the middle part. All materials actually have this property, so in theory you should always check this option. The ratio of amount reflection between the polygons facing away and polygons facing towards you, is controlled by the IOR. The lower you go, the less reflection there will be on the polygons facing towards you. So for glass, you should use 1.3-1.5 for IOR, but of course this also affects the look of the refractions! Metals for example are not transparant, so you can play with the ior as much as you like. They are however very reflective also on the polygons facing towards you, so you need to use high IOR values (15 for example), or you could just leave the fresnell unchecked, so that all polygons will reflect an equal amount.
Glossiness: the blurryness of the reflections. 1 is not blurry at all, 0 is very blurry.
The look (or the accuracy) of the blur is controlled by the subdivs. The higher the subdivs, the smoother the blur will be, but the longer the rendertimes! Usually you can use 3-8 subdivs (if you don't use the interpolation, see further down). An important factor here is also the AA settings. if you use good settings, the look of the blurred reflections will be better of course. So it's difficult to predict how your blur will look like if you test render with AA turned off. If you adjust the subdivs value while AA is turned off, you will most likely end up using way too high values in your final rendering when AA is turned on.
Interpolation is a way to speed up the calculation of glossies. It uses prepasses like with the irradiance map settings to calculate the glossies for a low resolution image first and then figueres out where it needs more 'attention' to further calculate more detail in the glossies. When using interpolation, you need to increase the subdivs drastically! Also the interpolation settings are very important here. The parameters are the same as for the irradiance map. Refer to vray.info or this forum for more info on these parameters.
Imo, the interpolation method isn't usefull in many cases, but sometimes you can benefit a lot from it. It depends on many factors like the shape of the surface, the amount of detail that is required etc... Sometimes you need to increase the interpolation settings so much, that you better don't use it and simply use low subdivs value. Especially for reflection glossies, I rarely use it.
Max depth is the number of times a ray bounces before reflection calculation stops. The old example is when you stand between two mirrors and you can see yourself an infinitive amount of times. You can limit this amount in vray by using the max depth value and this can speed up rendering.
The exit color is the color vray assigns to the ray when it reaches the max depth value.
All the same can be transposed to the refraction settings. The IOR of course controls the amount a ray is bent after it goes through a transparant surface.
The fog color is used to make thicker parts of a transparant object darker then thinner parts. The fog multiplier controls the amount of the effect, just play around with this, you'll notice the effect immediately. This usually requires low values (0.05 for example) otherwise your object will turn black.
Affect shadows will make your shadows colored, depending on your fog color and multiplier. Actually, these are fake caustics!!! This is very important to realize, because for this reason, when you turn on caustics for any object in your scene, the affect shadows option is neglected!!! Otherwise you would render double caustics (the real ones and the fake fog ones). Altough an option to not neglect the 'affect shadows' while using caustics would be great...
For more info about refraction glossies, refer to richard rosenmans excellent tutorial yo ucan find here:
www.richardrosenman.com/vray_absorption.htm
Mmmm that's kinda it I think. Also remember that glossy reflection replace the highlight setting you're used to in max materials. These are fake highlights. Also here, I would appreciate a fake highlight option for vray materials!
Vray Frame Stamp Variables:
%vrayversion
%filename
%frame
%rendertime
%computername (host computer name)
%date (current date)
%time (current time)
%camera (name of camera, if camera view, empty otherwise)
%w (image width)
%h (image height)
%ram (total physical memory present)
%vmem (total virtual memory present)
%mhz (cpu speed)
%cpu (cpu id)
%os (operating system)
Newcomers Basic Setup
posted by Michael Watkinsarchived on 18.6.2004
For those of you who are new and just want a starting point here is a basic setup I might use for an external scene.
AA to adaptive and leave it at its default settings (not saying it the best. just giving you a starting point)
you then want to turn on your indirect illumination.
Use irradiance map for now and set min max to something like -3 -1
nrm thresh clr thres and dist i usually set to 0.3 for all. (these things are explained in the help file as to what they actually do)
secondary bounce put the multiplier to 0.75 and maybe something like 8 bounces would do nicely. maybe 10
Environment rollout
turn on the override max and set the multiplier to 0.5 and not so blue. a very very very very light blue might look a little better.
Add a direct light to your scene and put its multiplier to 0.6 and turn on shadows and choose vray shadow.
These are the basic starting point settings i use then i start to customise. I will usually start ballancing light in the scene by changing the multipliers of the direct light and the vray environment light. when ive gone as far as that takes me i can then further ballance light and dark in the color mapping section.
Keep in mind its a basic setup. Before exploring other settings, 1st explore the ones I gave above. I would suggest exploring your Irradiance map settings 1st. raising and lowering the values to see the outcome. Then move onto your AA settings. And finally fool around with the color mapping. Once you have mastered these to be able to setup your scenes relitivly by instinct you can then move on to the other finer detailed settings.