Note: The scene for this tutorial is provided by Chaos Group and all scene assets by www.FlyingArchitecture.com

Part I: GI Settings, Color Mapping and Portal Lighting


Step 1. First Render

1.1. Open the scene (which can be found here, size 54 MB).

1.2. Render the scene with standard setting only..

As you can see the scene renders, but only renders using Global Illumination (GI) giving you a very dark interior space.

1.3. Add the sun by selecting the V-Ray Sun from the V-Ray toolbar (). Place the sun in your scene at an appropriate angle that best fits the scene. This sun will act as a direct light until you change it in the Environment settings.

1.4. In your V-Ray Options Editor (), select the Environment rollout and open the Texture Editor button “m” in your GI (skylight).

1.5. In your GI (Skylight) settings select the rollout under the preview and scroll to “TexSky”, and under the default sky options use Sun1.

1.6. Next, in your V-Ray Options Editor (), change the setting in your “Indirect Illumination (GI)” under Secondary Bounces Multiplier to Light Cache (Light Cache has more energy and provides a brighter scene)

1.7. Now, select the “Interior View-1” lets re-render and see the result.

1.8. In the Image sampler rollout change the Adaptive DMC Max Subdivs to 1. This is going to speed up the render for testing purpose.

1.9. Because we are testing lets go to the Output tab and lower the resolution width to 600.  Select “Get View Aspect” to update to your exact  Interior View-1 aspect ratio. This should give you 600 x 322 or something similar.  This will allow us to render more quickly.

1.10. In the Irradiance map rollout set the Min Rate to -5 and the Max Rate to -3.

1.11. In the Light Cache rollout the subdivisions should already be set to 500.

1.12. Render

Now we can see what our final result will start to look like.

Step 2. Tweaking the Exposure and Color Mapping

2.1. Since the scene looks too bright, we would like to darken it a bit. There are several ways to do this. One is to decrease the power of the light. However, this will make the indirectly lit areas of the image too dark while lit regions will become properly exposed. The most efficient way is to use the physical camera to adjust the overall exposure of the scene. This will also decrease the brightness of the sun in some areas that previously appeared overbright.

2.2. In the Camera rollout, increase the Shutter Speed to 60.

2.3. In the Color Mapping rollout set the color mapping to Reinhard and decrease the burn value to 0.3. The Reinhard color mapping is a blend between linear and exponential. If the burn value is 1.0, the result is linear color mapping, while if the Burn value is set to 0.0, the result is Exponential style mapping.  By decreasing the Burn value in Reinhard we should be able to reduce the overbright areas.

2.4. Another effect that we want to have on the scene is blurry shadows from the sun light entering through the windows. To achieve that effect we have to go to the Environment rollout and click on the Texture editor button "m" near GI(Skylight) again and change the "size" to 30.

2.5. Render:

The result is quite noisy, but it does give a good idea of what the scene lighting is like. Notice that the sun is burning some areas in the render

Step 3: Better Interior Lighting with Rectangle Lights (Simple Portal Light)

At this point, the illumination is good, but we may need more natural light from the outside.  To add more light lets add a Rectangle light at the windows to act as a Simple Portal light.  A Simple portal light will ignore any geometry behind it and produce direct light from the environment. We are using the V-Ray sun as our Environment light, so the simple portal light will get its color and intensity from the sun.  

3.1. Select the Rectangle Light from the V-Ray toolbar ()

3.2. Place your plane light in front of the windows and blinds as highlighted in yellow below.

3.3. Select the Rectangle Light (be sure its direction is pointing to the interior of the room) and in Your Light editor go to the Light Portal rollout and make the Rectangle Light that you just created a “Simple Portal Light”

3.4. Render

This brightens up our scene giving us a more realistic result.  If you want to add even more light to the room, without changing the intensity of the environment, you can also add another Rectangle Portal Light behind the camera to act as a second window. The only issue here is the overall quality of the render.

Step 4. Better Antialiasing and Less Noise

In the first steps we change the quality of the render to be able to have a fast preview, while we are working with the illumination. Our goal now is to improve the setting to achieve better antialiasing, better GI and less noise in my render.

4.1. Go to the Image Sampler rollout and set the Min Subdivs to 2 and the Max Subdivs to 6.

4.2. In the DMC Sampler rollout set the Noise Threshold to 0.008.

4.3. The sun shadow has a lot of noise. To avoid that, we have to increase the subdivs of the sun light. In the Environment rollout, click on the Texture editor button "M" near GI(Skylight) and increase the Shadows subdivs to 32.

4.4. Render the scene.

Rendering takes more time now as V-Ray needs to calculate a more precise Antialiasing solution.

Step 5: Better GI Solution

The Antialiasing looks okay now, but we still have a low GI quality. For this reason we have some missing and blurry shadows. We'll deal with those now.

5.1. In the Irradiance Map rollout, set the Min Rate to -3 and the Max Rate to -1 .

5.2. Change the Color Threshold to 0.3 .

5.3. Render

We do have better shadows definition, but we can see some splotches on the render. We'll adjust the HSph subdivs to improve that.

5.4. Set the HSph subdivs to 80.

5.5. Render.

Notice that this render is noise free and the GI solution is very good. But It can seem a bit flat. To improve that lets also add some Ambient Occlusion to the scene.

5.6. Open the Indirect Illumination (GI) Rollout and turn on Ambient Occlusion (AO).

5.7. Set The Amount to 0.3 and the Subdivisions to 32

5.8. Render.

By adding some AO to your scene it gives it some subtle depth.

Part II: Rendering the Final Image


We now have to render the final image.

Step 1. Adjusting V-Ray for Larger Resolution

1.1. Set the resolution width to 1600 and select “Get View Aspect”  It should give you 1600 x 859 or something similar.

We will need to adjust the irradiance map parameters: since we increased the resolution twice, we can decrease the irradiance map Min and Max rate.

1.2. Set the irradiance map Min Rate to -4.

1.3. Set irradiance map Max Rate to -1.

1.4. In the Light Cache rollout, set the Subdivs to 1000.

Step 2. Rendering the Final Image

2.1. In the Output rollout enable "Save render output" to automatically save the rendered image. Pick the image file extension and assign a name and a path. For increased precision, you can choose a 16-bit image format (for example, a 16-bit .png).

2.2. Render

The final scene for this rendering can be found here (183 MB).

Part III: Additional Scene Lighting Image


While the unlit room looks nice sometime you prefer to show your room lit up with some artificial lights.   While we won't be going over IES and artificial lighting in this Tutorial, this scene is setup with using some artificial lighting.

1.1. First lets start with turning all the lights in the room on. Open your layers tab in Rhino and turn on the Floor Lamp Lights, IES Lights, Ceiling Light, and TV Screen.  These lights are all nested inside their respective layers.

1.2. Render

Because our scene started off naturally lit, turning on the interior lighting in the scene provides us with a nice warmly lit space.

Now that you have the basics, go through the scene turn lights off and on, enable, and disable your sun light, and generally experiment with the scene to better understand V-Ray and its rendering capabilities.
Good Luck!