Quadtree Lod Crack
- The Cause of Crack Quadtree LOD algorithm is a part simplification method, each terrain piece has different resolution after it being dealt with.
- A New Quadtree-based Terrain LOD Algorithm Quadtree LOD algorithm will reduce the total number The Cause of Crack Quadtree LOD algorithm is a part simplification.
91 The Improvement on Terrain LOD Algorithm Using Quadtree Jian Wu1,2, 1,2Yanyan Cao1, Zhiming Cui, and Xiaojun Wang1 1 The Institute of Intelligent.
A New Quadtree-based Terrain LOD Algorithm Jian Wu, Yan-yan Cao, Zhi-ming Cui, Crack Elimination Algorithm Quadtree LOD algorithm will reduce the total.
Looking for an example on quadtree based LOD terrain
Ages ago 10 years I wrote a quadtree based terrain renderer, that directly reads Terragen-1 files. You need to supply a prerendered surface/illumination texture. The whole thing never was meant to be something serious. The first iteration of the code started as a keep me from boredom during a lengthy train trip, within about 6 hours. Then I added to it LOD and some other goodies.
I ve put the code as it was on my harddisk on Github, enjoy:
https://github.com/datenwolf/codesamples/tree/master/samples/OpenGL/qt_terr
This thing renders the terrain using immediate mode. Turning this in a vertex array based renderer is left as an exercise to the reader.
GPU-Aware Hybrid Terrain Rendering, 2012C. Dick, J. Krüger, R. Westermann Munich, Saarbrucken, builds on
rasterization and ray-casting in every frame simultaneously
to determine eye ray intersections
shifts workloads flexibly between the triangle setup stage and the
parallel execution units, depending on the GPU capacities
As is frequently the case with modern papers, there is no algorithms
or pseudocode or shader code, just a high-level overview of the approach.
Continuous Distance-Dependent Level of Detail for Rendering Heightmaps
CDLOD, 2010by Filip Strugar, originally
journal of graphics, gpu, and game tools, 2009
GPU-based rendering, quadtree based, smooth geomorphing based on
predictable detail across LODs.
Supports dynamic loading/paging of large datasets. No skirts.
Supports all graphics hardware with Shader Model 3.0 and above.
Demo and complete DirectX source code is available under a free
GPU Ray-Casting for Scalable Terrain Rendering, Eurographics
2009C. Dick, J. Krüger, R. Westermann Munich, Utah
The authors started with an existing terrain rendering system, which
handles very large out-of-core datasets using a quadtree, and replaced the
rendering portion with a GPU-based ray-casting algorithm. There are
many complex multi-pass operations, e.g. to exploit occlusion. It
performs well in certain cases with very high-resolution data with multiple
height samples per on-screen pixel, but poorly compared to normal
rasterization with higher screen resolutions and lower DEM resolutions.
No known public implementation.
Based on a terrain rendering system described in this paper:
Patches for GPU-Based Terrain Rendering,
WSCG 2007Yotam Livny, Zvi Kogan,
Jihad El-Sana Ben-Gurion University
Yet another approach using a quadtree, with the unusual approach of
handling each quad as four right triangles, each whose resolution is chosen
to match its neighbor, with a triangle strip running down the seam to stitch
Claims to balance computation load among the CPU and GPU and dramatically
reduces the communication between them, sending elevation as a vertex
texture via Fragment Buffer Object extensions FBO.
Integrates paging of elevation from disk and texture LOD as well.
Survey on Semi-Regular Multiresolution Models for Interactive Terrain
Rendering, 2007R. Pajarola, E.Gobbetti, 2007
A survey paper giving an overview of all the various semi-regular
terrain LOD approaches: models based on tiled blocks and nested regular
grids, quadtrees and triangle bin-trees triangulations, as well as
cluster-based approaches LOD error metrics and system-level data
management aspects of interactive terrain visualization, including dynamic
scene management, out-of-core data organization and compression, as well as
Rendering using Spherical Clipmaps, Eurographics 2006Malte Clasen and Hans-Christian Hege Zuse Institute Berlin
using GPU-based geometry clipmaps to handle spherical planets, using an
ambitious, novel approach which pushes a GPU to it limits
spherical coordinates centered at the viewpoint produce concentric rings
of detail of increasing size, so unlike nearly every other LOD approach,
there are no problems with gaps between adjacent areas of differing LOD
however, this requires doing plenty of math on the GPU, including trig
functions, and a vertex texture lookup which is as of 2006 only available
the bottleneck is the vertex texture lookup, which the authors feel might
be solved in future GPUs by a unified shader architecture
GPU-Friendly High-Quality Terrain Rendering Journal of WSCG
2006J. Schneider, R. Westermann Technische Universität München
divides the terrain into a flat array of 257x257 tiles, uses ribbons of
zero area polygons to fill the gaps between tiles
GPU programming is used to decode vertices as 9 bits X, 9 bits Y, 14 bits
re-use of vertices and progressive transmission of vertices and indices
for less bus traffic and better GPU cache behavior
paging is done with complex memory management, implemented as a mixture
LRU and a tightest fit TF strategy
the primitive used is indexed triangle fans
Terrain Rendering Engine TRE : Cell Broadband Engine Optimized Real-time
intriguing paper on a unconventional approach:
ray-casting simpler than ray-tracing using the Cell distributed-processing
architecture to achieve realtime framerates
the special hardware consists of a Cell Broadband
Engine CBE with one dual-threaded Power Processor Element
PPE with eight SIMD Synergistic Processor Elements SPE
interestingly, there are no triangles involved at
all in the rendering, just rays and heightfields
Streaming and Rendering of Large Terrains using Strip Masks, 2005describes a very simple paging approach using a simple grid of tiles, each
containing a simple strip mask
boundary gaps are filled using a texture shadow plane which has the
ground texture repeated just below the terrain
although crude, this works fairly well for very light devices such as PDAs
Rendering Procedural Terrain by Geometry Image Warping. Eurographics
Dachsbacher, M. Stamminger University of Erlangen-Nuremberg
describes a way to use the GPU to do most of the work with both CLOD and
one very interesting step is the calculation of an importance map which
factors distance, frustum and terrain surface characteristics
the procedural detail is a fairly straightforward noise function
no known public implementation
clipmaps: Terrain rendering using nested regular grids. Siggraph
applies the concept of texture clipmaps to regular grid elevation,
using the GPU to smooth the transitions between detail levels
simplifies purely on distance, so it doesn t fit high-contrast terrain
well, but polygon count can be pushed so high on modern hardware that it
the clipmap construction allows compression, so that they can claim a
memory usage of only 0.1 bytes per heixel, or less.
using GPU-based geometry clipmaps, 2005, A.
an extension of the previous algorithm to
perform nearly all computations on the GPU itself, thereby reducing CPU
the technique is easy to implement
although it requires an NVidia GeForce6-class card, and there is no
this paper also appears in the GPU Gems
Terrain Rendering Using Geometry Clipmaps, Nick Brettell, 2005
Nick implements the Losasso/Hoppe paper,
as well a several others, and compares their relative strengths and
weaknesses. However, there is no public implementation.
Planet-Sized Batched Dynamic Adaptive Meshes P-BDAM, IEEE
Visualization 2003Paolo Cignoni, Fabio Ganovelli, Enrico Gobbetti, Fabio Marton, Federico
Ponchio, and Roberto Scopigno of
claims: a batched host-to-graphics communication model which outperforms
other adaptive tessellation solutions, guaranteed overall geometric
continuity, exploits programmable graphics hardware, a compressed out of
core representation and speculative prefetching for hiding disk latency
the tessellation structure is topologically like a normal RTIN, but the
vertex locations are allowed to leave the grid for more efficiency
significant pre-computation is required
BDAM - Batched Dynamic Adaptive Meshes for High Performance Terrain
The open-source project RATMAN
contains an implementation of BDAM see
C-BDAM - Compressed Batched Dynamic Adaptive Meshes for Terrain Rendering,
long list of claimed features and benefits: simplicity of
data structures, overall geometric continuity for planar and spherical
domains, support for variable resolution input data, management of multiple
vertex attributes, efficient compression and fast construction times,
ability to support maximum-error metrics, real-time decompression and shaded
rendering with configurable variable level-of-detail extraction, and runtime
Real-time Terrain Rendering using Smooth Hardware Optimized Level of Detail,
pdf B. D. Larsen, N. J. Christensen, Technical University of Denmark
based on a regular grid, quadtree of triangulated tiles, with a hardware
vertex program to do geomorphing on each vertex
there is no significant difference in the framerates with or without
morphing which indicates that the morphing feature does not cause a
performance penalty when vertex programs are implemented in hardware
each tile is loaded into a display list, created as needed based on LOD of
surrounding tiles, rather than created each frame, to further cut down on
CPU usage and improve triangle throughput
their implementation enforces the constraint that two adjacent tiles may
their test implementation uses OpenGL and the NVidia vertex API on a
Algorithm: CLOD for Height Fields, 2001
Henri Hakl, University of Stellenbosch
based on frame-coherent ROAM, with an alternative geometric structure:
claims: better for triangle strips, fewer split and merge operations
uses 4 LIFO buffers instead of priority queues
T-junctions are avoided with ad hoc splits that are not
inherent in the geometric structure
Visualization of Large Terrains Made Easy, 2001
Peter Lindstrom, Valerio Pascucci, LLNL, in Proceedings of IEEE
mentions, and draws on, virtually every CLOD paper to date, including
Lindstrom s previous work, ROAM, Hoppe s papers, and interestingly,
prominent use of Jonathan Blow s nested spheres.
the two main innovations claimed are an efficient memory indexing
scheme for better paging performance, and a new split/cull/stripping
claims that previous approaches have been overly complicated, and
offers a new way which is simple and easy to implement, yet still
Terrain Rendering at High Levels of Detail pdf, 2000
presented at GDC 2000 by Jonathan Blow
summarizes the Lindstrom-Koller and ROAM approaches, then proposes a
major improvement in how to treat the ROAM error metric, by looking at
the variance as a spherical isosurface around each vertex
best understood by looking at the illustrations in his slides for the
lecture; browse all his writings
the benefit applies only. to frame-coherent ROAM implements
Jonathan discusses his approach vs.
Real-Time Generation of Continuous
Levels of Detail for Height Fields 1998
by Stephan Röttger, W. Heidrich,
Ph. Slusallek, H.-P. Seidel University of Erlangen-Nuremberg
uses a quadtree which corresponds to the height grid
very low memory requirement height value 1 byte
recommends using triangle fans, centered around each parent vertex, as
an efficient way to render a vertex quadtree
is available which is very fast and extensible to paging of large
ROAMing Terrain: Real-time Optimally Adapting Meshes, 1997 primary paper by
Mark Duchaineau et al, from IEEE Visualization 97 Proceedings
features claimed:optimizes flexible view-dependent error metrics,
produces guaranteed error bounds,
achieves specified triangle counts directly,
uses frame-to-frame coherence to operate at high frame rates
new site now has extensive implementation notes and Unix source.
Right Triangular Irregular Networks ps, 1997
Gregg Townsend at the University of Arizona
uses 12 bytes/vertex, plus the grid of elevation values, so typically
uses a sophisticated storage approach which avoids having to allocate
includes an example program with complete, functional source codethe sample program is designed to illustrate the LOD
it isn t optimized for rendering speed, e.g.. they generate
Articles and Presentations Describing Algorithms
Large Terrain, 2010 by skytiger A completely modern approach which uses a vertex shader to transform
world-space positions into texture-space, sample the height map using VTF
Vertex Texture Fetch and displace the height of the mesh, then use
on-the-fly interpolation to smooth the result.
The result: Uses almost no CPU, no CPU-to-GPU bandwidth, and is very
GPU friendly. There is no need for quadtrees, octrees, clipmaps, roam or
There are demonstration videos but no source code.
Rendering Massive Terrains using Chunked Level of Detail Control pdf Thatcher Ulrich, presented at the at the Super-size it. Scaling up to
Massive Virtual Worlds course at SIGGRAPH 02
a quadtree of chunks, where each chunk is a rectangular, precomputed
section of optimized geometry, and skirts to fill cracks rather than force
from the paper, advantages of this approach:
Low CPU overhead and high triangle throughput.
Efficient use of triangles within aggregates.
Texture LOD integrated with geometry LOD.
Easy to integrate with out-of-core storage.
Efficient, smooth vertex morphing; no vertex pops.
Low CPU load, even when viewpoint moves rapidly.
Non-trivial preprocessing required.
Uses more triangles than a primitive-level algorithm, for the same
Some data size overhead, depending on lossiness of preprocessing.
Continuous LOD Terrain Meshing Using Adaptive Quadtrees, 2000
Gamasutra article by Soul Ride
his approach uses a single quadtree of 3x3 blocks, with the LOD
computation performed directly on each block
the tree of blocks approach allows for memory to be used sparsely,
only where needed, instead of a single monolithic vertex array
it s handling an area of 64K x 64K meters, yet allows the finest grid
data to be 1m x 1m in selected areas
memory usage is typically around 12 bytes/vertex
Real-Time Dynamic Level of Detail Terrain Rendering with ROAM, 2000
Terrain Rendering Using Geometrical MipMapping, 2000
flipcode article by Willem H. de
a quadtree LOD approach, like Röttger s but has less detail about how
LOD levels are managed to avoid cracks
introduces a very direct analogy of texture MipMapping to terrain LOD,
Visualization of Large Textured Terrains, 2005Anders Brodersen, University of Aarhus
Claims to extend Boer s GeoMipMaps with efficient paging of large
textures. However, the texture handling is barely described one small
sub-section in section 5 of the paper. No known public implementation
Landscapespresentation at GDC 2001 by Glenn Corpes
includes a description of a regular-grid LOD algorithm which:
makes heavy use of precomputed vertex buffers, for each possible
deals with edge conditions by storing each possible permutation
the precomputed LOD only varies by a maximum of. 5 on adjacent
cells - this condition is assured by walking through the map and
dragging the LOD of high detail cells neighbors up.
A Fast Algorithm For Large Scale Terrain Walkthrough, 2001 pdf
Zhou, Jiaoying Shi, Zhigeng Pan
contains a good overview of the other papers on the subject
briefly describes a CLOD approach which prevents cracks by allowing
Real-time Continuous LOD for PCs and Consoles . ppt, 2000
no longer online presented at GDC 2000 by Louis Castle et al. Westwood Studios
based on Röttger s paper above, extends it with:
Simplified quadtree subdivision: fewer subdivision tests and
Linked quadtree storage: rather than in a height-field-sized
what they call a optional detail map is considered a fundamental
requirement variance by other algorithms
the detail map is a rather crude workaround for the problem that
their split metric is based only on distance
Large Scale Terrain Visualization Using The Restricted Quadtree
Renato Pajarola, IEEE Visualization 98
the approach looks very similar to Lindstrom-Koller 96, cleaned up a
little and fleshed out, and made unambiguously top-down
Fast Multiresolution Surface Meshing postscript,
M. H. Gross, R. Gatti, O. Staadt, Proceedings of the IEEE
a very math-intensive paper which uses a wavelet approach
doesn t use RTINs, but rather a lookup-table of special cases to
Terrain LOD algorithm is a dynamic and local dough sheet subduction algorithm. On the basis of the research on traditional quadtree algorithm, this paper proposed a.
Official Full-Text Publication: The Improvement on Terrain LOD Algorithm Using Quadtree on ResearchGate, the professional network for scientists.