Friday, 11 December 2009

Rendering: mental ray_Adding glow to the window glass

The above image was produced whilst at GMJ Design Ltd

In our latest book, we have covered a number of ways of emulating light without the need of creating a physical light.

Production companies often adopt similar methods to reduce the rendering times and retain the overall quality.
It is worth pointing out that the usage of Ambient Occlusion(i.e. AO) as a separate pass or/and directly from Max is utterly imperative for the final shot.

The following exercise will take you through another unique methodology of achieving similar results with reduced rendering times:

Another quick way of emulating “glow”/"light" on windows, is to in fact enable the glow function on the glass panes themselves.

To do this, simply go to the main material parameters, under the "refraction" group.

1-Reduce the transparency to about 0.9 to prevent the surface from being fully transparent.

2-To add a bit of blur to the transparency, decrease the glossiness to about 0.78. Note that, these values may vary depending on one’s camera angle...and the level of transparency/blurriness intended.

3-Next,change the colour swatch from white to a warm yellow.
Also, the "fast (interpolate)" function, can be enabled for quick and fast results, as the glossiness and its samples can often slow down the renders.However,it may create artifacts.

4-Pan down to the "self illumination (glow)" parameters and enable the "self illumination (glow)" function.

5-Under the "luminance" group, change it from "unitless" to "physical units: cd/m2)". Also, pick and choose any relevant bitmap (i.e. photo) that has a prominent light source.

Note: The "unitless" function often creates artifacts on glossy reflections, therefore, to be avoided at all costs.

Depending on time in hand, one can set the glow to generate light, or not, through the FG, by checking the "illuminates the scene (when using fg)" function.
...and... “...let there be light...”!!!

The final rendered image below was achieved using this technique. I hope you like it.

I hope you have found this post interesting.

More tips and Tricks:

Post-production techniques

Tips & tricks for architectural Visualisation: Part 1

Essential tips & tricks for VRay & mental ray

Photorealistic Rendering

Creating Customised IES lights

Realistic materials

Creating a velvet/suede material 




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