U g I n f o r d e s I g n e r s

V-Ray for SketchUp
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Even if the Environment lighting is set to the desired level for the final scene, you will still wind up 
having to adjust it based on the materials and other lights that will be added to the scene. Very 
often the camera got moved during this process and the quality and brightness are not what you 
were expecting. Even though the interior lighting is under control, once the camera is pulled out 
from the box, you will get the bright white rendered result as the image on the left
.
It will still be necessary to add light in the room, adjust the brightness and render as image on the 
right.
V-Ray for SketchUp
62

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Clasification of Light bounces
Direct light- This is the light which is calculated directly from a light source. If GI were not enable, or if 
there were no engine selected of either primary or secondary bounces the rendered image would be the 
result of only the primary bounces. It is not necessary to specify an engine for these calculations as these 
are done through standard raytracing. Environment light is not considered a form of direct light.
Primary bounces- this the light which is the first bounce after the direct light hits a surface. Usually these 
bounces have the greatest effect on the scene in terms of the indirect lighting, as these bounces retain a 
significant portion of light energy. Environment light is calculated as a primary bounce.
Secondary bounces- this is all of the light which bounces around the scene after the primary bounce. As light 
bounces around a scene, its intensity, and therfore its affect on the final illumination, becomes less and 
less. Because of this secondary bounces can all be calculated through a single method. With exterior 
scenes these bounces have a relatively insignificant effect on the final result, however with interior 
scenes the bounces can become as important as primary bounces. 
It is important to remember these classifications when evaluating an image’s quality, and adjusting settings 
to either achieve better or faster results.
In order to calculate indirect light within V-Ray a render engine must be specified to compute those 
calculations. Each engine has its own method of calculation and each with its own advantages and 
disadvantages
V-Ray uses two render engines to calculate the final rendered image. Open Indirect Illumination control 
panel under Options. There are Primary Engine and Secondary Engine options in the panel below. 
There are four options for Primary Engine: Irradiance Map, Photon Map, Quasi Monte-Carlo and Light Cache. 
Default is set to Irradiance Map.
There are three options for Secondary Engine: Photon Map, Quasi Monte-Carlo and Light Cache. Default is set 
to Quasi Monte-Carlo or you can select None to not use this Engine.
When switching between different engines, the control panel
s
will also change according to the assigned 
engine.
Choosing different Render Engines