LuxBlend tutorial: creating a simple interior scene

From LuxRender Wiki

by Pinko (Luca) / translated by Francesco Ceccon

With this simply tutorial I'll try to explain the making of a simple interior scene using Blender as modeling program and LuxRender 0.5 as photorealistic renderer.

creating the model

For this tutorial I'll use one of my models. Let's get started.

First I create a cube of the following dimensions: x=6, y= 6, z=0.05

Then I make the walls and make the openings of doors and windows.

When I'm ready with the structure I start making the shutters:

Then I make the baseboards, the furniture and all the objects that must be in the final scene; at this point I make the ceiling and the other structure that may be visible in the “Camera” sight, like the hint of balcony.

Usually when I'm creating a scene I add the ceiling last, so that it doesn't block the view of the other objects.

The final scene showing from various sides:

Then I choose the best shot for the “Camera” sight.

Next I'll start with the definition of the materials.

materials

Usually I prefer to assign materials right after having modelled a single object, but this is just a personal preference. ;)

The first material I define is the “Wall” material and I always use a dirty white “Matte”

Then I make the floor material, in this case it's a parquet, so I use a plastic material with a texture for the “Diffuse” channel and grey for the “Specular” channel because the parquet has a medium specularity. (Specular could be pure white for a complete reflection or black for a dull surface)

This is the preview of “parquet” material ;)

Another material one always encounters in interior renderings is glass. LuxRender has many presets for transparent materials like glass, silicon, hydrogen, water and petrol.

I always use the following settings for the glass material:

This is the table with the preset of transparent materials:(To see this view click the preset button in the IOR section)

Of course you have to assign the appropriate textures to all materials in the scene. In this example I have to define the shutters material. I use an aluminium material, fortunately LuxRender has many metallic materials available.

This is the aluminium we are going to use in the scene.

In the scene there are a lot of materials, from here on I'll only show images of the settings I used.

orange furniture

green carpet

white plastic

black plastic

arm chair

Now we are going to define lights.

lights

In the scene there are two types of lights: a sunlight and the "mesh light" (also called emitter) of the lamp near the television.

To get the sunlight to work, create a sun lamp object in Blender and set the environment type to "sunsky" in LuxBlend's Cam/Env tab. The position and the angle of the "Sun" element of Blender defines the angle and the intensity of LuxRender's sun.

The next image is an example of sunlight and artificial light.

When you use two different lights the meshlights's "Gain" controls its intensity compared to the solar light. In a nutshell if you increase the gain of the artificial light the solar light will appear less strong. Next there are three example images:

The reason for this behaviour is that LuxRender will automatically try to find the right exposure for the scene. When the emitter strength is increased, the scene would be overexposed if the same exposure would be used, so the program compensates by making everything darker.

It is very difficult to give absolute tips about the light strenghts, you have to find this balance in empirical way.

portals

We have to add two portals to our scene.

This is necessary because we have some openings that let in sunlight. Portals helps LuxRender in the computation and increase the speed of the render process.

Now I'll try to briefly explain portals. The simplest way is to cover the door and window openings with planes that are slightly bigger than the opening itself.

Next you have to assign a new material to these planes, for the sake of simplicity we are going to name this material "PORTAL". Then we select this material in the exporter and assign the "portal" material type to it.

Now we can selecte the render preset and start the rendering.

Personally I use the Medium-low MTL/Path Tracing (RECOMMENDED) because I think it has a good time/quality ratio.

Next you can see two example, in the first scene there is only the sunlight, in the second there are both sunlight and the artificial light (meshlight/emitter).

Ciao Luca. :)