# 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.

## Before starting¶

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

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 editor

Create a new environment by clicking on the button in the toolbox, and name it overcast

## Using an HDR environment map¶

Open the new environment, and change its type to 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.

There are many commercial HDR envmaps available for purchase. We provide you a few low resolution envmaps for download :

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.

You may now start the render and obtain the following picture after a few minutes:

## Next steps¶

In the next tutorial, you will see how to use existing packaged materials in your scene : Using external library materials