User Study of Quantized MIP Level Data In Normal Mapping Techniques

Abstract

 The standard MIP mapping technique halves the resolution of textures for each level of the MIP chain. In this thesis the bits per pixel(bpp) is reduced as well. Normal maps are generally used with MIP maps, and todays industry standard for these are usually 24 bpp.The reduction is simulated as there is currently no support for the lower bpp in GPU hardware. Objectives: To render images of normal mapped objects with decreasing bpp for each level in a MIP chain and evaluate these against the standard MIP mapping technique using a subjective user study and an objective image comparison method. Methods: A custom software is implemented to render the images with quantized normal maps manually placed in a MIP chain. For the subjective experiment a 2AFC test is used, and the objective part consists of a PDIFF test for the images. Results: The results indicate that as the MIP level is increased and the bpp is lowered, users can increasingly see a difference. Conclusions: The results show that participants can see a difference as the bpp is reduced, which indicates normal mapping as not suitable for this method, however further study is required before this technique can be dismissed as an applicable metho