Splat/Mesh Blending, Perspective Rasterization and Transparency for Point-Based Rendering

Ga�l Guennebaud, Lo�c Barthe and Mathias Paulin

Eurographics Symposium on Point-Based Graphics, 2006, Boston, United-States.

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In this paper we present multiple simple and efficient improvements for splatting based rendering systems. In a first step we derive a perspectively correct splat rasterization algorithm suitable for both efficient implementation on current GPU and the design of fast dedicated rasterization units taking advantages of incremental calculations. Next, we propose a new efficient and high-quality approximation of the optimal EWA (Elliptical Weighted Average) filtering framework. We also show how transparent point-clouds can be rendered by current GPU in an order independent way by using a modified depth-peeling approach. Finally, in the context of hybrid points and polygons rendering systems, we present a simple mechanism to smooth the transitions between the different representations. Combined to previous contributions in the field, these improvements lead to a high-quality, performant and full-featured hardware-oriented splatting rendering system.

The Mario Botsch's EWA filtering approximation. Our new EWA filtering approximation.

EWA filtering approximations: left is the Mario Botsch's approximation and right is our new approximation.

Splat/polygon transition smoothing. Left: classic hybrid rendering (look at the discontinuity artifacts). Center: the gradient is the sum of weight comming from the splatting process. Right: the previous gradient is used to smooth the transition without additionnal cost !

Transparency with complete depth-peeling. Transparency with only the first 3 layers. Transparency with only 3 layers and our blending heuristic.

Transparency: from left to right, full depth-peeling (8 layers), depth-peeling with only 3 layers without and with our blending heuristic.