Authors:
Anupam Agrawal
1
;
M. Radhakrishna
1
and
R.C. Joshi
2
Affiliations:
1
Indian Institute of Information Technology (Deemed University), India
;
2
Indian Institute of Technology, India
Keyword(s):
Terrain visualization, Out-of-core algorithms, Multiresolution modeling, View-dependent refinement.
Related
Ontology
Subjects/Areas/Topics:
Computer Vision, Visualization and Computer Graphics
;
Geometry and Modeling
;
Multi-Resolution Modeling
Abstract:
Interactive visualization of very large-scale terrain data in scientific visualization, GIS or simulation and training applications is a hard problem. The grid digital terrain elevation and texture data are not only too large to be rendered in real-time but also exceed physical main memory capacity. Therefore out-of-core management of digital terrain data is an essential requirement. Further to bring photorealism in visualization, it is required to place multiple collections of man-made objects such as buildings, lampposts etc. as well as natural objects such as trees, grass etc. on top of the terrain surface. In this paper we have proposed an integrated approach for effective out-of-core visualization of terrains populated with large collection of static heterogeneous objects. We have developed an efficient tile-based out-of-core view-dependent Level of Detail (LOD) mesh simplification algorithm for real-time rendering of large terrains. Instead of manipulating individual triangles,
the algorithm operates on clusters of geometry called blocks of aggregate triangles. Hence the amount of work CPU must perform is greatly reduced. The formation of long triangle strips for LOD blocks also solves the CPU-to-Card bandwidth problem. The tile-based multiresolution terrain geometry framework has been extended to support large satellite or aerial imagery textures. To display large collection of objects over the terrain while maintaining the real-time frame rate, an efficient object handling method has been proposed using paging technique and object instantiation. User is allowed to control the objects locations, scales and orientations. The algorithms have been implemented using Visual C++ and OpenGL 3D API and successfully tested on different real-world height maps and satellite phototextures of sizes upto 16K*16K coupled with thousands of static objects on PCs.
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