In the Indirect Illumination tab the only thing I changed were the Irradience mapsettings. To change these parameters you have to be sure that GI (Global Illumination) is turned on.
At first I chose a very low preset so that I could get fast render results. For the final render I changed them to high.
Here is a little trick I applied. I didn't render the whole image in one go. I first rendered out the Irradiance map separately and then changed the setting later to render from the Irradiance map. To achieve this, under Global Options "Don't render final image" needs to be turned on, to only render the Irradiance map. When the render is completed the newly rendered map is plugged in to the From File setting under Mode in Irradiance map. (Don't forget to turn "Don't render final image" off again).
After all settings were more or less final, I rendered out a pre-final image. I imported it to Photoshop and did some simple color correction, played around with exposure, sharpening filters, vignetting, camera distortion, grain, chromatic aberration etc. When I was happy with everything, I re-rendered a full resolution image, composited it again in Photoshop and exported it (Fig.07).
This is the main part of the lighting tutorial, where I will explain which methods I used to achieve the result. After looking in detail at the real-life scene I came to the conclusion that only two light sources were needed. Because V-Ray works with physically correct attributes it should therefore be possible to achieve a good, realistic result.
The first light source is a direct light. It was created within the V-Ray render settings and called "VrayGeoSun". It is responsible for the sharp shadows that come from the window blinds. To get the accurate position of the shadows it is very important to get an identical scene/model size, so the shadows fall accordingly.
In the direct light settings the light position was acquired from the correct time and date settings when the photo was taken. Therefore the light angle and intensity were the same as in the photo.
Keep in mind that you have to alter the shadow subdivisions to about 32 when rendering the final image. For test renderings I kept the value at 8 (Fig.08).
The second light source is used as an environment light, which is responsible for the white light reflections that fill up the room. It is a simple VrayRectlight, with a white light emitting.
When positioning a light, keep in mind that the arrow of the light flows in the scene, and when altering the size of the light never scale V-Ray lights because it destroys the physical correctness of light. Rather, change the light size with the U and V parameters in the corresponding light settings. With the shadow subdivision it's the same with the direct light, only set them to 32 or even 64 for the final rendering. In hand with the VrayGeoSun, a VraySkyis created which gives a realistic sky reflection in the rendered scene (Fig.09 - 10).
After the two light sources were placed, the position was locked to ensure no accidental movements. Here is the first test rendering (Fig.11).