On‐the‐fly generation and rendering of infinite cities on the GPU

Abstract

Figure 1: Infinite cities with highly detailed, context-sensitive buildings can be generated in real-time on the GPU using a parallel shape grammar. The visible 28 km 2 of the city contain up to 47 000 buildings. In full detail, these buildings would expand to 240 million rules, producing 2 billion triangles. Generating an initial view with adaptive level of detail (7 million triangles) from scratch takes 500 ms. Exploiting frame-to-frame coherence, we update the geometry for successive frames in 50 ms on a standard PC, even if the viewer moves at supersonic speed. AbstractIn this paper, we present a new approach for shape-grammar-based generation and rendering of huge cities in real-time on the graphics processing unit (GPU). Traditional approaches rely on evaluating a shape grammar and storing the geometry produced as a preprocessing step. During rendering, the pregenerated data is then streamed to the GPU. By interweaving generation and rendering, we overcome the problems and limitations of streaming pregenerated data. Using our methods of visibility pruning and adaptive level of detail, we are able to dynamically generate only the geometry needed to render the current view in real-time directly on the GPU. We also present a robust and efficient way to dynamically update a scene's derivation tree and geometry, enabling us to exploit frame-to-frame coherence. Our combined generation and rendering is significantly faster than all previous work. For detailed scenes, we are capable of generating geometry more rapidly than even just copying pregenerated data from main memory, enabling us to render cities with thousands of buildings at up to 100 frames per second, even with the camera moving at supersonic speed.

Procedural feature generation for volumetric terrains using voxel grammars

“…Shape grammars have also been modified to run on massively parallel architectures. A GPU-based shape grammar algorithm was created by [27] in order to create infinitely large cityscapes. They utilised the parallel algorithm found in [28] and a set of rules to generate geometry for realistically planned cities.…”

“…This makes the assumption that the entirety of the geometry data is available for rendering, if it is required. One of the concepts [27] introduced was their method of visibility pruning. This completely skipped evaluation of any rules that would create buildings outside the view frustum of the current camera, eliminating the generation of any redundant geometry and reducing GPU memory usage.…”

A Survey of Algorithmic Shapes

“…Recent work by MARKUS STEINBERGER et al shows how to overcome this problem in a GPU implementation [47]. Furthermore, the same authors presented methods to interactively generate and render only the visible part of a procedural scene using procedural occlusion culling and the level of detail [48].…”

Built by Algorithms – State of the Art Report on Procedural Modeling –

“…Recent work by MARKUS STEINBERGER et al (2014) shows how to overcome this problem in an GPU implementation. Furthermore, the same authors presented methods to interactively generate and render only the visible part of a procedural scene using procedural occlusion culling and level of detail (Steinberger et al, 2014b) The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XL-5/W4, 2015 3D Virtual Reconstruction and Visualization of Complex Architectures, 25-27 February 2015, Avila, Spain…”