Distortion
In the real world, camera lenses cannot be perfect; therefore, they introduce errors (aberrations) in the images they capture. One of the most noticeable errors, called distortion, causes the resulting image to be pulled in or pushed out, so that long straight lines become bowed.The Distortion shader applies a physically accurate camera lens distortion to an image. And because Distortion is a lens shader, it can create a severe distortion without causing the stretching problem associated similar post-rendering effects.
Procedure
In Modeler, create a flat polygon. This will be the surface onto which effect will be rendered. The animator needs to position the camera to directly face the flat polygon, so that no unwanted distortion occurs. Also, make sure that the normals of the polygon are facing the camera, or make the surface two sided.
In the surface settings for the polygon, select Distortion as the shader.
Edit its parameters.
Parameters
Amount controls how much the image gets distorted. Small values will cause only a slight bending, larger values will cause greater bending.
Type controls whether the distortion is inward (Pin Cushion) or outward (Barrel). Barrel is the type of distortion most commonly associated with wide angle camera lenses.
