Interior Illumination by Mario Malagrino, Italy

Dear Architects and interior designers, this is one of my tutorials that I wrote for my students of the Florence Design Academy. This tutorial is about the illumination of a room which is illuminated by sunlight coming through a window (ideal for living rooms, kitchens and bed-rooms).

There are many different illumination techniques that I teach for an interior-rendering. This one is quite easy. We will use 2 different kind of lights. One is the "MR spot light" and the other is the photometric "free area light”. Before we begin it is very important to inform you that we will use "mental ray" as render engine (3d studio Max 8).Mental ray is a very stable render engine, and it allows having very realistic renderings. Since we are using Mental ray for this tutorial it is very important to use "real measurements" for all the interior/furniture’s that we have to create. Otherwise the result will not be optimal. It would be important to have already a bit experience with the mental ray settings since this tutorial will not explain all settings.

The first light ( mr area "spot" light ) must be located outside the room. You must move the target of the light trough the window and place it inside the room.



Let's see a few settings. Select the light and go to the modify panel. Over there check "shadows on" and select ray traced shadows (this is necessary whenever you will make renderings with mental ray).

I put in the multiplier slot 0.8, but this doesn't mean that you must have the same number since later we will add other lights which will influence the brightness of the room. Change the colour to a very bright orange-yellow colour to simulate the sun rays colour.

In “Area light parameters” (modify panel) you have the possibility to make the shadow softer increasing the size (hight, width) of the light. To give the impression that outside the room the environment is very bright ( like in the final rendering -image D-) you must create a big white self-illuminated box in front of the window. After this step select the "mr area spot light" and exclude (In the Exclude-panel from the modify panel) the self illuminated box from illumination + shadow casting. Otherwise it will create a shadow in the room. Try now to make a rendering.... It will be quite dark...

Image A - First Rendering only with mr area "spot" light + Final Gather enabled

How can we make more realistic our rendering? Let's go to the "render scene panel". Choose indirect illumination. Now check the Final Gather box. Put a low number in the Samples slot (50) to make a quick test rendering and see the difference. It will be similar to image A. For higher quality you must increase the number of samples. In my rendering I put 600 (this will take more render time). Don't put more than 1000 samples. You don't need such big numbers for a final rendering. Try to go up with the number making small test renderings. First try 150...than 250... than 400 etc.


Let's increase the realism of the rendering. Still under final gather there is a slot called -trace depth- "max bounces" where we can increase the number. Let's put 4 (never use more because it will take really really too much render time). This option sets the number of times diffuse light bounces are calculated for a single diffuse ray. In other words: it allows us to have the same energy that we can see when sunlight is illuminating a room. Now you should have more or less the result of image B (next page). Let's add a new light.

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