Interior Illumination by Mario Malagrino, Italy

The size must be smaller than the size of the wall that you have deleted. Don't locate it too close to your room; leave a small space between room and light. Otherwise you will "burn" the surfaces which are too close to the light. I Put around 850 CD in the slot for the Intensity. Try to make a test rendering. You should have this result of below image.



The result of the luminosity depends not only on the intensity but also on the size of the light that you create. You will notice that increasing the size of the area light you will have more or less the same effect of increasing the intensity number. The last step that you can do to improve the realism is to add a “glare” filter. This will give a glowing/shiny effect on the brightest parts of your surfaces. Try always to change settings trying to discover the optimal balance of size/location/intensity of the lights. I tried this tutorial with success also on interiors with more than 2 windows... for each window adds a small area light and a spot light.

To make a final adjustment of the Brightness/contrast/Mid-Tones of the rendering you should use the exposure control. Exposure Controls are able to adjust the output levels and color range of a rendering. Go to RENDERING -> Advanced Lightening-> choose in Exposure Control:  Logarithmic Exposure Control.


Problems, errors and solutions: If your rendering is too dark probably you must increase the intensity of your last free area light, or you must increase the size of the free area light.

-Color-bleeding effect: to avoid this effect put a lower number in "max bounces"

-To long render times: This kind of illumination requires really a long render time. To spend less time you can reduce the "max bounces" number to 1 or 2 and make a bit brighter all lights.

-The rendering is full of big dark dots: this happens if in final gather you have a low number in the samples slot. If you still have this imperfections (below image) after you have increased the number of samples try to add a bigger number in Final Gather RADIUS slot.

- How to make VERY fast test renderings: Make the rendering size small (example: 100*75 pixels).It will be for sure too small to see details, but you can clearly see if the illumination of the room is too dark or too bright.


Ps: Remember that this tutorial teaches a technique of illumination, not what values to put in the light parameter slots. Since the final result of the rendering depends by the size of the room; the intensity, the color, the size and the location of the lights, you must do many test renderings and experiments to get the correct values. I hope this tutorial was useful for you :)

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