Setting up a cloudy environment
In this tutorial, we will see how to change the environment lighting in the scene.
Environment lighting describes the way your scene is lit from a very far distance, as opposed to the light emitted by the scene objects themselves. It is a very convenient way to simulate a sky light for outdoor scenes, but can be also be used in other situations.
You should have already exported your scene with SketchUp or Rhinoceros to an ocxml file. If not, load a SketchUp file or follow Exporting a Rhinoceros scene to Ocean 2014
You may also load the scene file exported at the previous tutorial : cloudenv-start.ocbin
Modifying the default environment
The Rhinoceros exporter created a default environment, generally called uniform or skylight. You may find it in the object list toolbox.
Using an HDR environment map
HDR environment maps (envmaps) are high dynamic range, spherical pictures of the environment, and are widely used in computer graphics for realistic lighting. Ocean accurately computes the lighting produced by these environment maps, each pixel being virtually used as an independant light source.
In this example, we will reproduce a cloudy sky environment, using this one.
The HDR envmap can be used as an environment, by setting the environment type to envmap:
The base child node is a spectrum, and is set by default to a 6500K blackbody. Just click on it and set the gain parameter to 1E-4. This setting changes the overall lightness of the sky, it is not very important as the default camera adjusts its gain automatically in post-processing steps, but starting with plausible value is better.
Then click on the image child node and set it to the path of the HDR image (nantes-overcast.exr)
Finally, click on the "Apply" button at the bottom of the edit window.
Now select the overcast environment in the render settings toolbox.
You may now start the render and obtain the following picture after a few minutes:
In the next tutorial, you will see how to use existing packaged materials in your scene : Using external library materials in your scene