Maya 2012 Tutorial
How to Add Refraction in Maya
Refraction causes the light to bend as it passes through an object. Materials refract light in different ways. The number that is assigned to a material's refraction is called it's Refractive Index. For instance, air has a Refractive Index of 1.0, glass is 1.6 and water is 1.3. For a complete list of materials and their Refractive Index, see Maya help or do a web search.
To render material refraction you need to enable Raytracing in the Render Options for a Maya Software render or use Mental Ray.
Add a polygon plane to the workspace by choosing Create > Polygon Primitives > Plane.
Select the plane, then right-click the plane and choose Assign New Material > Blinn.
In the Attribute Editor, blinn tab, click the checkerbox next to the Color slider to open the Create Render Node.
In the Create Render Node, 2D Textures section, right-click Checker and choose Create Texture.
Add an Octahedron to the workspace by choosing Create > Polygon Primitives > Platonic Solids (include options).
In the Platonic Solids dialog box, select Octahedron for Platonic Type. Click Create to add your new shape.
In the front view use the Move tool (w key) to move the octahedron so it sits on the plane.
Select the Scale tool (r key) and scale the plane so it is at least four times larger than the octahedron.
Select the octahedron, then right-click the octahedron and choose Assign New Material > Blinn.
In the Attribute Editor, blinn tab, set the Transparency to 90% transparent, Eccentricity to 0.1 and Reflectivity to 0.8.
In the Attribute Editor, Raytrace Options section, click the Refractions checkbox. Set the Refractive Index to 1.6.
Click the Render Settings icon and choose Render Using: Maya Software. Click the Maya Software tab and set Quality: Production Quality.
In the Render Settings, Maya Software tab, Raytracing Quality section, click the Raytracing checkbox.
Click the Render Current Frame icon to view your image. Notice how the checker pattern becomes distorted by the octahedron refraction.
Try a Mental Ray Render
To view your render with Mental Ray, change Render Using: to Mental Ray (Step Twelve). Click the Quality tab and set the Quality Presets to Production. Render your image (Step Fourteen) to view the refraction.
Also consider using the mia_material_x_passes material (instead of Blinn) when rendering with Mental Ray. The material includes several glass presets that can be accessed by clicking the Presets button.