Issues in terrain visualization for environmental monitoring applications
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Issues in Terrain Visualization for Environmental Monitoring Applications. Ricardo Veguilla [email protected] Nayda G. Santiago [email protected] Domingo A. Rodriguez [email protected] Electrical and Computer Engineering Department

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Issues in terrain visualization for environmental monitoring applications

Issues in Terrain Visualization for Environmental Monitoring Applications

Ricardo Veguilla [email protected]

Nayda G. Santiago [email protected]

Domingo A. Rodriguez [email protected]

Electrical and Computer Engineering Department

University of Puerto Rico, Mayagüez Campus

June 23, 2006


Walsaip

Raw Data

Servers

Computed Data

Servers

WALSAIP

WALSAIP: Wide Area Large Scale Automated Information Processing

INTERNET

Data Representation

Systems

Computational Signal

Processing Systems

Signal Data

Post-processing

Information Rendering

Systems

Signal Conditioning

System

Sensor Array

Structures

Pre-processing Stage

Processing Stage

Post-processing Stage


Walsaip vte visual terrain explorer

WALSAIP-VTE (Visual Terrain Explorer)

WALSAIP

Cyber-Infrastructure

Information Rendering System

(Visualization)

Automated Data

Processing

Data Acquisition


Data size complexity and performance

Data size, complexity, and performance

  • 3D visualization is computationally expensive

  • We want to visualize large, complex geometrical models

  • Critical for interactive terrain visualization due to the sheer size of the data sets


Issues in terrain visualization for environmental monitoring applications

Level of Detail


Level of detail lod

Level of Detail (LOD)

  • Premise: It is inefficient to use many polygons to render object that will only contribute to a few pixels of the rendered scene.

  • Conclusion: Use less detail for small, distant portions of the scene.

  • Approach: Use geometric simplification operations to eliminate redundant information while satisfying both performance and visual accuracy constrains.


Our goal

Our Goal

Review available terrain rendering LOD techniques, with interested in:

  • How to exploit video card (GPU) processing capabilities

  • Handling data larger than available memory (out of core, distributed computing)

  • Identify best approach for a future implementation of the VTE


Basic components

Basic Components

  • The initial mesh: A polygonal representation of the terrain at either the minimum resolution level (base mesh) or the maximum resolution level (full mesh)

  • Updates operations: Operation which simplify or refine a mesh.


Characteristics of lod algorithms

Characteristics of LOD Algorithms

  • LOD Granularity

  • LOD Distribution

  • Processing direction

  • Terrain Data Structure

  • LOD Data Structure


Lod granularity

76 polys

2,502 polys

69,451 polys

251 polys

LOD granularity

  • Discrete LOD: finite set of pre-computed LODs

  • Continuous LOD: further simplifies discrete LODs to produce a continuous spectrum of detail

251 polys

69,451 polys

N polys


Lod distribution

LOD distribution

  • Uniform

  • View-dependent


Processing direction

Processing direction

Top-down (refinement or subdivision algorithm)

Bottom-up (simplification or decimation algorithm)


Terrain data structure

Terrain data structure

Height fields

(Regular)

Triangulated Irregular Networks

(Irregular)


Lod data structure

LOD data structure

Quadtree: a rectangular region recursively subdivided into four uniform quadrants.

Bintree (Binary triangle tree) : a rectangular region is recursively subdivided into two triangles.


Issues in terrain visualization for environmental monitoring applications

Survey of Algorithms


Approaches

Approaches

  • Traditional Approach

    • 80’s

    • The basic unit is the triangle

    • Traditional LOD techniques generally aimed to produce the ideal level of detail

  • Modern Approach

    • 2000’s

    • Basic unit is the triangle cluster or patch

    • Concerned with maximizing GPU usage and minimizing CPU usage


Issues in terrain visualization for environmental monitoring applications

Traditional Approach


Real time continuous lod rendering of height fields

Real-time, continuous LOD rendering of height fields

  • Using a quadtree with discrete LODS generated off-line

top-down refinement

bottom-up simplification


Issues in terrain visualization for environmental monitoring applications

ROAM

  • Uses two ordered priority queues: one for split operations and the other for merge operations.


View dependent progressive meshes

View-dependent Progressive Meshes

  • a TIN-based, view dependent terrain LOD algorithm

  • Continuous LOD is produce by recursively removing triangles from off-line generated blocks of terrain.


Issues in terrain visualization for environmental monitoring applications

Modern Approach


Geometrical mipmapping

Geometrical MipMapping

Quadtree technique that work on blocks of uniform detail

Simplification based on vertex removal

Selection based on worst-case view parameters

Eliminates cracks by changing vertex connectivity at the block boundary


Triangle cluster techniques

Triangle cluster Techniques

  • Cluster: small triangle meshes optimized for GPU processing

  • Cluster are cached on the video card memory.

  • Hierarchy is used for view culling

ACL

Frustrum Occluded Cluster

Inactive Cluster

Visible Cluster

Occluded Cluster

ACL = Active Cluster List


Geometry clipmap

Geometry Clipmap

A multi-resolution mesh formed by combining nested concentric grids center about the view position

Resulting view

View culling


Conclusions

Conclusions

  • In Use of triangle cluster patches as basic rendering unit allow:

    • maximizing GPU usage*

    • better coupling of the geometry and the texture

    • out-of-core operation*

    • The ideal level of detail (an irregular mesh) is in compatible with GPU maximization (which require regular meshes)

*points of interest for the WALSAIP-VTE project


Lod and walsaip

LOD and WALSAIP

WALSAIP

Cyber-Infrastructure

Automated Terrain

LOD Generation

Terrain Visualization

Terrain Data

Acquisition


Walsaip vte status

WALSAIP-VTE - Status

  • Java and OpenGL implementation with LOD based on GeoMipMaps.

  • Future research on out-of-core data management for remote data acquisition


References

References

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  • Luebke, D., Reddy, M., Cohen, J., Varshney, A., Watson, B., and Huebner, R. (2003). Level of Detail for 3D Graphics, Morgan-Kaufmann, Los Altos, CA.

  • Fowler, R. J. and Little, J. J. 1979. (1979). “Automatic extraction of Irregular Network digital terrain models”. Proceedings of the 6th Annual Conference on Computer Graphics and Interactive Techniques. SIGGRAPH '79. ACM Press, New York, NY, pp 199-207.

  • Samet, H. (1984). “The Quadtree and Related Hierarchical Data Structures”. ACM Comput. Surv. Vol. 16, No. 2, pp 187-260.

  • Puppo, E.(1998), “Variable resolution triangulations”, Computational Geometry, Vol. 11, No. 3-4, pp.219-238.

  • Leclerc, Y. G. and Lau, S. Q. (1995). “TerraVision: A Terrain Visualization System”, Technical Note 540. AI Center, SRI International, http://www.ai.sri.com/pubs/files/778.pdf 02/15/2006

  • Reddy,M., Leclerc,Y., Iverson,L., and Bletter, N. (1998) "TerraVision II: Visualizing Massive Terrain Databases in VRML," IEEE Computer Graphics and Applications, Vol.19, No.2, pp. 30-38.

  • Williams, L. (1983). “Pyramidal parametrics”. Proceedings of the 10th Annual Conference on Computer Graphics and interactive Techniques SIGGRAPH '83. ACM Press, New York, NY, 1-11.

  • Zach, C., Mantler, S., and Karner, K. (2002). “Time-critical rendering of discrete and continuous levels of detail”. VRST ’02: Proceedings of the ACM symposium on Virtual reality software and technology, pp. 1–8.

  • X. Bao and R. Pajarola, (2003) “Lod-based clustering techniques for efficient large-scale terrain storage and visualization,” Proceedings of the SPIE - The International Society for Optical Engineering, Vol. 5009, pp. 225–35.

  • Lindstrom, P., Koller, D., Ribarsky, W., Hodges, L. F., Faust, N., and Turner, G. A. (1996). “Real-time, continuous level of detail rendering of height fields”. In Proceedings of the 23rd Annual Conference on Computer Graphics and interactive Techniques SIGGRAPH '96. ACM Press, New York, NY, 109-118.

  • Röttger, S., Heidrich, W., Slussallek, P., and Seidel, H. P. (1998) “Real-Time Generation of Continuous Levels of Detail for Height Fields”. Proceedings of the 6th International Conference in Central Europe on Computer Graphics and Visualization, 315--322.

  • Duchaineau, M., Wolinsky, M., Sigeti, D. E., Miller, M. C., Aldrich, C., and Mineev-Weinstein, M. B. (1997). “ROAMing terrain: real-time optimally adapting meshes”. Proceedings of the 8th Conference on Visualization '97. R. Yagel and H. Hagen, Eds. IEEE Visualization. IEEE Computer Society Press, Los Alamitos, CA, 81-88


References cont

References (Cont)

  • Hoppe, H. (1996). “Progressive meshes”. Proceedings of the 23rd Annual Conference on Computer Graphics and interactive Techniques SIGGRAPH '96. ACM Press, New York, NY, 99-108.

  • Hoppe, H. (1997). “View-dependent refinement of progressive meshes”. Proceedings of the 24th Annual Conference on Computer Graphics and interactive Techniques International Conference on Computer Graphics and Interactive Techniques. ACM Press/Addison-Wesley Publishing Co., New York, NY, pp. 189-198.

  • Hoppe, H. (1998). “Smooth view-dependent level-of-detail control and its application to terrain rendering”. Proceedings of the Conference on Visualization '98. IEEE Computer Society Press, Los Alamitos, CA, pp 35-42.

  • De Boer, W. H., (2000). “Fast terrain rendering using geometrical mipmapping”. http://www.flipcode.com/articles/article-geomipmaps.pdf. 02/15/2006

  • Brodersen, A. (2005). “Real-time visualization of large textured terrains,” GRAPHITE ’05: Proceedings of the 3rd international conference on Computer graphics and interactive techniques in Australasia and SouthEast Asia, pp. 439–442.

  • Cignoni, P., Ganovelli, F., Gobbetti, E., Marton, F., Ponchio, F., and Scopigno, R. (2003). “BDAM - batched dynamic adaptive meshes for high performance terrain visualization,” Computer Graphics Forum, Vol. 22 No. 3 pp505-514.

  • Levenberg, J. (2002) “Fast view-dependent level-of-detail rendering using cached geometry”. VIS ’02: Proceedings of the conference on Visualization ’02.

  • Yoon, S., Salomon, B., Gayle, R., and Manocha, D. (2005). "Quick-VDR: Out-of-Core View-Dependent Rendering of Gigantic Models," IEEE Transactions on Visualization and Computer Graphics, Vol. 11, No. 4, pp. 369-382.

  • Zhu. Y (2005), “Uniform Remeshing with an Adaptive Domain: A New Scheme for View-Dependent Level-of-Detail Rendering of Meshes”. IEEE Transactions on Visualization and Computer Graphics Vol. 11, No. 3, pp. 306-316.

  • Cohen, J., Luebke, D., Duca, N., and Schubert, B. (2003) “GLOD: A geometric level of detail system at the OpenGL API level,” VIS ’03: Proceedings of the 14th IEEE Visualization 2003 (VIS’03), pp. 85.

  • Losasso, F. and Hoppe, H. (2004). “Geometry clipmaps: terrain rendering using nested regular grids”. ACM Trans. Graph. Vol. 23, No. 3 , pp. 769-776.

  • Schneider J., and Westermann, R. (2006) “Gpu-friendly high-quality terrain rendering,” Journal of WSCG, Vol. 14, No. 1-3, pp. 49–56.


Questions

Questions?

  • Ricardo Veguilla

    [email protected]


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