BumpMap2

This demo features a flat, 2D surface that uses a bump map to make it appear as if 3D structures are present.

Similar to the BumpMap1 demo, this scene features a common method used in the computer graphics community to introduce apparent surface height variation into smooth surface. However, a bump map does not actually displace the surface of the object. The input image file for this demo is attached to a flat surface, but features gradients that will manipulate the surface normal in a way that can be quantified and checked for testing. The input bump map is show below:

The scene is defined in the geometry/demo.glist file, using a pair of instances of the same OBJ file describing a 1x1 square. the OBJ is instances with two different materials, with the second featuring the bump map. The scale is used to define how a digital count gradient is translated into a unit length normal vector deflection.

To run the simulation, perform the following steps:

The image below shows the resulting radiance image from the simulation. The shading across the surface varies because the bump map manipulates the normal across the plane in a way that mimics the surface illumination variation as if the 3D structures were present. Note that since the surface is still flat, there are not any true shadows cast by these apparent surface features.

The image below is the "normal to view angle" truth image, which shows how the bump map is manipulating the surface normal. The darker values on the background indicate that the angle is small (nearly normal to the view) where as the brighter values show where the normal is being deflected to make it appear as if the surface has slope.

The final image shows the average Z intersection truth of each pixel, which highlights that the bump map does not change the location of the surface, but rather the normal at the surface.