Glass Rendering Tutorial with Vray in 3dsmax
by admin
Author: Jan Rybar
Software: 3dsmax, VRay
Our work is primarily artistically oriented – we are given plans and sketches, and we are entrusted with the task of making great imagery and movies. Occasionally however, based on the evolution of our software (renderers), clients are requesting for more realism-based images. Architecture in particular, is always about the use of correct materials and while lots of new buildings, mainly offices and public spaces, have large glass facades, you need to deal with creating realistic glass.
Just recently, we wrapped up a huge reconstruction project for a skyscraper in NYC and the client asked us to simulate several versions of their facade design. This meant we would have to translate technical data to our renderer (in this case V-Ray). I would like to take this opportunity to point out just a small fragment of our daily work and while it is nothing secret or special, it is still not too obvious a factor for most people.
Most modern glass panels are built from several sheets of glass and each sheet has different properties. It means that if you want to simulate reality, you need to model based on real specs (i.e. glass sheet has thickness and between sheets there is some certain space, usually filled with a special gas). Then you need to set up your materials according to the technical data you’ve received. In this tutorial, I will show you a table where I got the glass transparency and exterior reflectivity (I also have interior reflectivity but it wasn’t really affecting final result so I just skipped it). The basics of what I’ve done is having the glass change its values based on the angle at which you are looking at – and it is for all main properties of glass (transparency, reflectivity).
In the image above, you can see the basic material of my glass sheet. In the final version, I have more than one sheet used to build the whole glass panel and it is analogically the same process. What affects the changing values based on angle is FALL-OFF map in Max, but I need more control over it…so to speak. You can modify the fall off curve in the map itself, but it is very rough and I needed to be exact because otherwise it just won’t work properly. So the work does a remap of the Fall-Off map with a Gradient map and then everything becomes easy and pretty straightforward. There is one step in-between and it is to convert the values from the technical sheet to what you need in Max which is shown below.
There is also one small issue in regards to the color of glass that you usually get in “L.a.b.” color space – it is just another color space and you can convert these values in Photoshop easily, see below.
And the color itself then goes to FOG color in our V-Ray material.
Lastly, you need to apply all material to the correct sheets in your model and then you’ll get perfect interpretation of a real glass panel.
Tip:
To work properly, you should work in Linear Color Space with lighting by HDR or Physical Sky.
That’s all and I hope this can help someone.
Ok but what are you using in bump map to distort the reflections as they are on a skyscrapers?