### Abstract

In this paper we propose a novel visibility-culling technique for optimizing the computation and rendering of opaque isosurfaces. Given a continuous scalar field f(x) over a domain D and an isovalue w, our technique exploits the continuity of / to determine conservative visibility bounds implicitly, i.e., without the need for actually computing the isosurface f ^{-1} (w). We generate Implicit Occluders based on the change in sign of f* (x) = f(x) -w, from positive to negative (or vice versa) in the neighborhood of the isosurface. Consider, for example, the sign of f* along a ray r cast from the current viewpoint. The first change in sign of f* within D must contain an intersection of r with the isosurface. Any additional intersection of the isosurface with r is not visible. Implicit Occluders constitute a general concept that can be exploited algorithmically in different ways depending on the framework adopted for visibility computations. In this paper, we propose a simple from-point approach that exploits well-known hardware occlusion queries.

Original language | English (US) |
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Title of host publication | Proceedings - IEEE Symposium on Volume Visualization and Graphics 2004. VolVis 2004 |

Editors | D. Silver, T. Ertl, C. Silva |

Pages | 47-54 |

Number of pages | 8 |

State | Published - 2004 |

Event | Proceedings - IEEE Symposium on Volume Visualization and Graphics 2004. VolVis 2004 - Austin, TX, United States Duration: Oct 11 2004 → Oct 12 2004 |

### Other

Other | Proceedings - IEEE Symposium on Volume Visualization and Graphics 2004. VolVis 2004 |
---|---|

Country | United States |

City | Austin, TX |

Period | 10/11/04 → 10/12/04 |

### Fingerprint

### Keywords

- Computational geometry
- Graphics hardware algorithms
- Isosurfaces
- Marching cubes
- Occlusion culling
- Visibility computations
- Volume visualization

### ASJC Scopus subject areas

- Engineering(all)

### Cite this

*Proceedings - IEEE Symposium on Volume Visualization and Graphics 2004. VolVis 2004*(pp. 47-54)

**Implicit Occluders.** / Pesco, Sinésio; Lindstrom, Peter; Pascucci, Valerio; Silva, Cláudio T.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*Proceedings - IEEE Symposium on Volume Visualization and Graphics 2004. VolVis 2004.*pp. 47-54, Proceedings - IEEE Symposium on Volume Visualization and Graphics 2004. VolVis 2004, Austin, TX, United States, 10/11/04.

}

TY - GEN

T1 - Implicit Occluders

AU - Pesco, Sinésio

AU - Lindstrom, Peter

AU - Pascucci, Valerio

AU - Silva, Cláudio T.

PY - 2004

Y1 - 2004

N2 - In this paper we propose a novel visibility-culling technique for optimizing the computation and rendering of opaque isosurfaces. Given a continuous scalar field f(x) over a domain D and an isovalue w, our technique exploits the continuity of / to determine conservative visibility bounds implicitly, i.e., without the need for actually computing the isosurface f -1 (w). We generate Implicit Occluders based on the change in sign of f* (x) = f(x) -w, from positive to negative (or vice versa) in the neighborhood of the isosurface. Consider, for example, the sign of f* along a ray r cast from the current viewpoint. The first change in sign of f* within D must contain an intersection of r with the isosurface. Any additional intersection of the isosurface with r is not visible. Implicit Occluders constitute a general concept that can be exploited algorithmically in different ways depending on the framework adopted for visibility computations. In this paper, we propose a simple from-point approach that exploits well-known hardware occlusion queries.

AB - In this paper we propose a novel visibility-culling technique for optimizing the computation and rendering of opaque isosurfaces. Given a continuous scalar field f(x) over a domain D and an isovalue w, our technique exploits the continuity of / to determine conservative visibility bounds implicitly, i.e., without the need for actually computing the isosurface f -1 (w). We generate Implicit Occluders based on the change in sign of f* (x) = f(x) -w, from positive to negative (or vice versa) in the neighborhood of the isosurface. Consider, for example, the sign of f* along a ray r cast from the current viewpoint. The first change in sign of f* within D must contain an intersection of r with the isosurface. Any additional intersection of the isosurface with r is not visible. Implicit Occluders constitute a general concept that can be exploited algorithmically in different ways depending on the framework adopted for visibility computations. In this paper, we propose a simple from-point approach that exploits well-known hardware occlusion queries.

KW - Computational geometry

KW - Graphics hardware algorithms

KW - Isosurfaces

KW - Marching cubes

KW - Occlusion culling

KW - Visibility computations

KW - Volume visualization

UR - http://www.scopus.com/inward/record.url?scp=15944390882&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=15944390882&partnerID=8YFLogxK

M3 - Conference contribution

SN - 0780387813

SN - 9780780387812

SP - 47

EP - 54

BT - Proceedings - IEEE Symposium on Volume Visualization and Graphics 2004. VolVis 2004

A2 - Silver, D.

A2 - Ertl, T.

A2 - Silva, C.

ER -