Making-of: Creating fog with Thea for SketchUp


by | Apr 24, 2017 | Tips | 11 comments

In this article, we will be taking a look at the new way of adding fog in your scenes with the newly added features in Thea for SketchUp v1.5.09.540.1462 onwards. The two new options for adding and controlling fog, can be found in:

  1. The Global Medium options in the Environment Tab.
    Thea Rendering Window > Environment Tab > Global Medium > Fog
  2. The new Cloud Preset.
    Simply create & apply a new material and use the Cloud Material Preset from the Thea Tool window.

1. Making of the Pathway Scene

The first scene that we will be looking into is an exterior scene (image 1) for testing the fog option in Global Medium settings.

Setting Up the Environment…

For this specific scene, there was no point selecting a detailed background image since we were aiming for a foggy look and wanted to see the fog effect on the Street Lights too.
From the Environment Tab of the Thea Rendering window, we used a blurry HDR image in the Illumination Channel (image 2) and decreased its intensity, so that the lighting from Street Lights would be more pronounced.

Enabling Fog…

Now that we have our scene ready, we need to enable Fog. This can be done by going to Thea Rendering Window > Environment Tab. From here, we need to switch to ‘Global Medium’ and select the ‘Fog’ option from the drop-down.
There are three parameters that control Fog.
Fog Intensity, Top and Base Level (m).
As the name states, the Fog Density slider can be used to define how dense the fog will be.
The rest of the parameters control the minimum and maximum height of the fog.
Please note that the thicker the fog is, the more time it will take to calculate the image. So, it is usually good to keep the fog height to the necessary minimum.

2. Making of the Entrance Scene

In our second scene, we will be looking into a simple interior scene (image 4) that was created to test the Cloud Material Preset. The model has a few long & narrow openings that help us better seeing the effect of the fog in the interior.

So, let’s go through the needed steps in order to create the final rendering.

Creating the fog container…

The most important thing, to begin with, is the container object. Fog needs a surface that will be acting as a container and for that, we created a box that encloses the whole scene (image 5).

Creating a material for the container…

With our container surface created, we will now create a SketchUp material (image 6) and give it a name that makes sense (ex. Box-Medium). Using the Bucket tool, apply the new material to the container.

The next step is to assign the Cloud Material Preset to it, so let’s open the Thea Tool window and with the Thea Cursor, click on the Container to grab its material. From the Presets drop-down, switch to ‘Cloud’. (image 7)

As you may have noticed, the only option for the preset is the color, but we will leave it like that because we will be using SketchUp’s material settings to control the overall look of the fog.

Assigning the Cloud Material as a Container to the Camera…

The last thing that we need to do is to assign the Cloud Material that we created (Box-Medium) as a container to the camera. In this way, when the camera is being placed inside the container object, it will not give us black renderings.

This can be done by switching to the Camera Tab of the Thea Tool window (image 8). In the Container drop-down, select the material that was assigned to the container (Box-Medium). Thea will automatically assign it as a container to the active camera.

Controlling the overall look of the fog…

Everything has been setup and the scene is ready to render. The only thing missing now is a way to control the color and density of the fog. We can easily do this by editing the material from SketchUp’s material editor.

To control density, use the opacity slider. To change color, use material’s color picker. (Image 9)

Rendering the final image…

You can set up the scene by using any Render & Display setting you feel that looks best. In our final image, we used a high contrast CRF profile and increased the overall exposure by changing the ISO, f-number and shutter values so that fog looks more pronounced.

In the following animation you can see the effect of the opacity slider by giving values from 0% to 100%.