Billboard clouds for extreme model simplification

Abstract

a) (b) (c) (d) Figure 1: Example of a billboard cloud: (a) Original model (5,138 polygons) (b) false-color rendering using one color per billboard to show the faces that were grouped on each (c) View of the (automatically generated) 32 textured billboards (d) the billboards side by side. AbstractWe introduce billboard clouds -a new approach for extreme simplification in the context of real-time rendering. 3D models are simplified onto a set of planes with texture and transparency maps. We present an optimization approach to build a billboard cloud given a geometric error threshold. After computing an appropriate density function in plane space, a greedy approach is used to select suitable representative planes. A good surface approximation is ensured by favoring planes that are "nearly tangent" to the model. This method does not require connectivity information, but instead avoids cracks by projecting primitives onto multiple planes when needed. For extreme simplification, our approach combines the strengths of mesh decimation and image-based impostors. We demonstrate our technique on a large class of models, including smooth manifolds and composite objects.

Multi-Resolution Foliage Faithful to the Visual and Botanic Concepts

“…All our tree models are generated from L-system defined as Eq. (9) in which the productions from P 1 to P 4 replace apex A by a set of internodes F , leaves L and two new apices A contained in module B. Parameter it presents the deriving iteration of the L-system. Parametric Lsystem provides a convenient mathematical framework for Curves marked with ' ,' '*' are generated from our method on GPU and CPU separately, while curves marked with '+' present geometric method in Ref.…”

“…Some approaches have been developed to convert polygon models to other graphic primitives such as impostors, 8 billboard clouds. 9 These techniques generate discrete level of details and always incur popping artifacts when adapting the detail. To overcome those problems some special treatments like frame sequential interpolation 13 or using 3D textures representing parts of a dense forest to render large scenes by volume slicing.…”

“…To overcome this problem, some special multiresolution simplification methods are designed for the foliage composed of sparse non-connected leaves. Most often, imposter 8 and billboards 9 are two common methods used to represent the distant objects or trees. Later on, leaf-collapsing 10 and pruning 11 are introduced to simplify the foliage of trees with polygonal models in a progressive way.…”

“…= 10, N l = 2560 N = 12, N l Tree structures generated by parametric L-system defined as Eq (9). with different values of constants listed inTable I.…”

Speed Tree-Based Forest Simulation System

“…In the mean while geometry is divided into branches, fronds, leaves, cards, meshes and Billboards [8]. Tree-Data Middleware encapsulates data with tree as the main structure.…”