View-Dependent Textured Splatting for Rendering Live Scenes

R. Yang, D. Guinnip and S. Lai

Goal

A novel approach to render low resolution point clouds with multiple high resolution textures---the type

of data typically from real-time vision systems.

A Typical Way:Triangulation

robust 3D triangulation is a challenging computational problem, which means real-time triangulation is not yet feasible.

It can have the side effect of magnifying outliers.

Rendering Results from a Live Scene

Triangluar Mesh Rendering

VDTS Rendering

Point Splatting Rendering

Related Work

Qsplat [in Siggraph 2000]

Surfel [in Siggraph 2001]

VDTM [in Siggraph 1996]

Real-time VDTM using projective textures[in 9th Eurographics 1998]

Unstructured lumingraph rendering[in Siggraph 2001]

Two directions in Splat

Speed: rendering in real time by using multiresoltuion and LOD control techniques.

Quality : Carefully balancing points sampling density or precisely texture mapping

Visibility Issues

Projecting a three dimensional object to a two dimensional image plane, in most cases cause surface elements to overlap. Such overlapping can cause visual artifacts when occlusions and disocclusions are present.

Anti-Aliasing

Unlike most splating algorithm, VDTS uses splats that are usually much bigger than one screen pixel. As a result, anti-aliasing for high resolution textures can be handled directly by the graphics hardware.

Texture anti-aliasing

•Each splat has only one color

•Each splat is rendered with projective texture-mapping

Visibility processing

The visibility problem is equivalent to the shadow determination problem.

Fully supported by graphics hardware

Visibility Clipping

The visibility processing can be problematic at surface boundary.

In the presence of high resolution depth map, we can compare the fragment depth with the actual depth. If the difference is too large, then we know it is likely a part of extruding splat that should really be transparent.

The large circle represents one view, P and Q are splats leading to inaccuracy in silhouettes.

Results of Visibility Clipping

Bunny data set rendered with visibility clipping disabled/enabled