Automatic LOD selection

Abstract: In this paper a method to automatically generate transition distances for LOD, improving image stability and performance is presented. Three different methods were tested all measuring the change between two level of details using the spatial frequency. The methods were implemented as an optional pre-processing step in order to determine the transition distances from multiple view directions. During run-time both view direction based selection and the furthest distance for each direction was tested in order to measure the performance and image stability. The work was implemented in the Frostbite game engine and tested using data from DICE. The result is a method that generates transition distances by calculating the spatial frequency of the exclusive or comparison between the silhouette of a ground truth mesh and each level of detail. The transition distances generated using the automatic LOD selection tool was evaluated using visual empirical tests and performance measurements comparing the performance of a scene using automatic generated distances and manually selected distances. The tests shows that the resulting method produces good transition distances for meshes where the reduction is visible in the mesh silhouette. The values might need a bit of tweaking in order to account for other image artifacts than silhouette changes but provide a good guidance to the artists.