icon in the shader’s property editor.
Creating a Reflection/Environment Map
Reflection mapping, also called environment mapping, can be used to simulate an image reflected on an object’s material, but without needing to use raytracing (actual reflection). It can also be used to add an extra layer of environment-based reflection to an object’s reflective, raytraced surface.
The illustration on the left shows an insect’s eyes with its reflection property activated: notice the flower’s reflection in the eyes — this is raytraced reflection.
The illustration on the right has a reflection map (clouds) in addition to the reflection property (flower). The reflection map is an environment shader that reflects a texture (in this instance, clouds) in the surface’s reflective areas.
Reflection Mapping and Raytraced Reflections
You can define whether reflections are Raytracing Enabled or Environment Only from the surface shader’s property editor.
1. Select the object whose reflective surface you want to modify.
2. Choose Modify > Shader and click the Transparency/Reflection tab.
3. For the Reflection options, set the Reflection Mode:
• Raytracing Enabled reflections are slower to render on the object’s surface because they are actually computed for everything around them. This includes the environment map which is combined with the raytraced reflections.
• Environment Only reflections are much faster to render on the object’s surface because they are simulated based on a specified texture which is defined in an environment shader. There are no inter-object reflections calculated when this mode is active, only the reflection map appears on the object’s surface.
Environment shaders are used mainly to create an environment that completely encompasses a scene. To simulate this environment, an environment shader can be applied to a geometric object or to a scene’s render pass so that all reflective objects are affected by the global environment map.
Creating a Global Background Environment
The most common use for an environment shader is to create a background that is visible from any camera angle at any distance and reflected on the surfaces of objects in your scene. To do this you apply an environment shader to a render pass.
To give a scene an environment map
1. Select the pass for which you want to generate the background environment and open its Render Pass Property Editor [Properties Reference].
2. Click the Pass Shaders tab.
3. In the Environment stack window, click Add to select an environment shader from the shader library. See Environment Shaders [Shader Reference].
The Environment shader maps an image in a spherical, cubic, or cylindrical shape around the scene. This shader can also be used to light a scene with a High Dynamic Range (HDR) image (see Using Environment Maps to Light a Scene).
4. Click OK when you have chosen a shader—it appears in the shader stack list.
5. To give the shader a texture to use as an environment, select the shader from the stack window and click Inspect. This opens the shader’s property editor. For more information on how to use a particular environment shader, click the icon in the shader’s property editor.
Creating an Environment on an Object
Rather than create an environment that encompasses an entire scene, you can work on a smaller scale and create a specific environment for a single object. The object is usually reflective and is given its own environment map to speed up rendering.
To give an object an environment map
1. Select the object to which you want to apply an environment shader. Make sure that you have applied a material to it.
2. From the Render toolbar, choose Get > Shader > Environment > Environment Map or More... to open a list of environment shaders you can use. See Environment Shaders [Shader Reference].
3. When you have chosen a shader—it is connected to the material node’s environment input.
4. The shader’s property editor opens where you can give it a texture to use as an environment. For more information on a shader’s parameters, refer to its help topic by clicking on the 
in the property editor.
Using Environment Maps to Light a Scene
You can light your scenes with images using the Environment shader. Like other environment shaders, this one surrounds the scene with an image. However, this shader has a set of parameters that allow you to control the image’s contribution to final gathering and reflections.
Although you can use any image to light the scene this way, you will get the best results using a High Dynamic Range (HDR) image. That’s because HDR images contain a greater range of illumination than regular images, making them better able to simulate real-world lighting.
For more information about using HDR Images in Softimage, see Using High Dynamic Range (HDR) Images.
To light a scene using an image
1. Apply an environment map to a render pass or the selected object as described in Using Environment Map Shaders. Use the Environment shader.
2. When the Environment shader’s property editor opens, click the lock icon to keep it open as you continue working.
3. Open the mental ray Render Options Property Editor for the pass you want to render with the environment.
4. Click the Final Gathering tab, and select Enable. Make sure to copy these settings to the active render region to preview final gathering in the render region (choose Render > Regions > Region Copy > Current Pass to Active Viewport).
5. From the Environment shader’s property editor, select an image clip to use as an environment map. Click the New button to create a new clip from file or from an existing image source.
6. From the Environment Mode list, choose the appropriate mode for mapping the image:
- Spherical maps the image spherically around the scene.
- Cylindrical maps the image cylindrically around the scene.
- Cubic Strip takes an image in which the faces of a cube are laid out horizontally, side by side, and maps it in a cubic shape around the scene.
- Cube Cross takes an image in which a cube has been unfolded to look like a cross and maps it in a cubic shape around the scene.
- Cube Cross Sideways is a cubic cross, but rotated 90 degrees.
7. Adjust the Background parameter to control the degree to which the image appears as the scene’s background.
8. Adjust the Reflections parameter to control the intensity of the reflected environment map. Higher values create brighter reflections.
9. Adjust the Image parameter to control the intensity of final gathering lighting.
10. Adjust the Transformation settings, if necessary, to transform the environment map image.
Creating an Image Based Lighting Render Pass
To speed up the process of lighting your scene with an image, you can use the Image Based Lighting render pass preset. Creating a new render pass using this preset automatically applies the Environment shader to the pass and enables final gathering in the render options. Of course, you can modify the pass to alter the image based lighting effect or limit the number of objects that it affects.
For more information about render passes and how to customize them, see Passes & Partitions [Rendering].
To create an image-based lighting pass
1. From the Render toolbar, choose Pass > Edit > New Pass > Image Based Lighting.
2. When prompted, specify whether you want to use an existing image clip or create one from file.
- If you use an existing image clip, a dialog box appears containing a list from which you can select an image clip.
- If you create a new image clip, a browser opens in which you can select the file with which to create the clip.
3. Once you select an image clip, a new render pass, called HDRI by default, is created and set as the current pass.
4. In the pass property editor adjust the pass settings.
5. Click the Pass Shaders tab and adjust the Environment shader settings (as described previously) until you’re satisfied with the results.
6. When your pass setup is ready, render the pass.
Autodesk Softimage v.7.5