Dynamic Scene Graph: Enabling Scaling, Positioning, and Navigation in the Universe

Emil Axelsson, Jonathas Costa, Cláudio Silva, Carter Emmart, Alexander Bock, Anders Ynnerman
2017 Computer graphics forum (Print)  
Figure 1 : Accurate rendering of a real scale model of the New Horizons spacecraft taking measurements on Pluto. The model of about 2 m size is shown in its correct location relative to Pluto, which is about 6 · 10 12 m from the coordinate system origin with the stars of the constellation Ophiucus (about 10 18 m) in their correct 3D positions. High precision is required for computing the correct location of images on the surface of Pluto as well as correctly rendering the shadow cylinders of
more » ... h Pluto and its moon, Charon. Abstract In this work, we address the challenge of seamlessly visualizing astronomical data exhibiting huge scale differences in distance, size, and resolution. One of the difficulties is accurate, fast, and dynamic positioning and navigation to enable scaling over orders of magnitude, far beyond the precision of floating point arithmetic. To this end we propose a method that utilizes a dynamically assigned frame of reference to provide the highest possible numerical precision for all salient objects in a scene graph. This makes it possible to smoothly navigate and interactively render, for example, surface structures on Mars and the Milky Way simultaneously. Our work is based on an analysis of tracking and quantification of the propagation of precision errors through the computer graphics pipeline using interval arithmetic. Furthermore, we identify sources of precision degradation, leading to incorrect object positions in screen-space and z-fighting. Our proposed method operates without near and far planes while maintaining high depth precision through the use of floating point depth buffers. By providing interoperability with order-independent transparency algorithms, direct volume rendering, and stereoscopy, our approach is well suited for scientific visualization. We provide the mathematical background, a thorough description of the method, and a reference implementation.
doi:10.1111/cgf.13202 fatcat:yjvu4c5hhfdz5ajwemghnu6i4u