manolas
/
vcglib
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Improved a lot!

This commit is contained in:
Paolo Cignoni 2005-11-12 18:20:25 +00:00
parent fd8e9de787
commit c61676a906
1 changed files with 46 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
apps/tridecimator/readme.txt
View File

@ -6,7 +6,7 @@
Visual Computing Lab http://vcg.isti.cnr.it /\/| Visual Computing Lab http://vcg.isti.cnr.it /\/|
ISTI - Italian National Research Council | ISTI - Italian National Research Council |
\ \
Metro 4.05 04/05/2005 TriDecimator 1.00 2/10/2005
All rights reserved. All rights reserved.
@ -24,59 +24,53 @@ for more details.
--- Synopsis --- --- Synopsis ---
Metro is a tool designed to evaluate the difference between two triangular meshes. tridecimator fileIn fileOut face_num [opt]\
Metro adopts an approximated approach based on surface sampling and point-to-surface distance computation. Where opt can be:\
Please, when using this tool, cite the following reference: -e# QuadricError threshold (range [0,inf) default inf)
-b# Boundary Weight (default .5)
-q# Quality threshold (range [0.0, 0.866], default .3 )
-n# Normal threshold (degree range [0,180] default 90)
-E# Minimal admitted quadric value (default 1e-15, must be >0)
-Q[y|n] Use or not Quality Threshold (default yes)
-N[y|n] Use or not Normal Threshold (default no)
-A[y|n] Use or not Area Weighted Quadrics (default yes)
-O[y|n] Use or not vertex optimal placement (default yes)
-S[y|n] Use or not Scale Independent quadric measure(default yes)
-B[y|n] Preserve or not mesh boundary (default no)
-T[y|n] Preserve or not Topology (default no)
-H[y|n] Use or not Safe Heap Update (default no)
-P Before simplification, remove duplicate & unreferenced vertices
P. Cignoni, C. Rocchini and R. Scopigno Supported formats: PLY, OFF, STL
"Metro: measuring error on simplified surfaces"
Computer Graphics Forum, Blackwell Publishers, vol. 17(2), June 1998, pp 167-174 -- Some technical notes --
Available at http://vcg.sf.net
This simplification tool employ a quadric error based edge collapse iterative approach.
Each possible collapse is scored taking into account
- its quadric error
- its quadric boundary error
- the normal variation caused by the collapse itself
- the future quality (aspect ratio) of the triangles involved in the collapse
The simplification can ends when the desired number of triangles has been reached.
The 'Safe Heap Update' change the set of edges re-inserted in the heap
after a collapse resulting in a vertex v; this option put back in the
heap not only incident in the vbut all the edges of the triangles incident
in v. It slows down a lot.
The 'Scale Independent quadric' is useful when you want simplify
two different meshes at the same 'error'; otherwise the quadric
error used in the heap is somewhat normalized and independent
of the size of the mesh.
The Normal threshold avoid to make large changes in variation of the normal
of the surfaces, but on the other hand it prevent the removal of small 'folded'
triangles that can be already present. Therefore in most cases is not very useful.
Cleaning the mesh is mandatory for some input format like STL that always
duplicates all the vertices.
You can find some sample mesh to test in the 'Metro Sample dataset' package downloadable from sourceforge.
For any question about this software please contact:
Paolo Cignoni ( p.cignoni@isti.cnr.it )
--- General Info ---
Metro is a tool designed to evaluate the difference between two triangular meshes.
Metro adopts an approximated approach based on surface sampling and point-to-surface distance computation.
Three different surface sampling methods are implemented:
* Montecarlo sampling (pick k random samples in the interior of each face)
* Subdivision sampling (recursively subdivide each face along the longest edge and choose the sample in the center of each cell)
* Similar Triangles sampling (subdivide each face F in k polygons similar to F and sample the face in correspondence with the vertices of these polygons, internal to F)
Note that the three methods described above are used to sample only the interior of each face.
A different scheme is used to sample vertices and edges: vertices are sampled in the straightforward manner,
while edges are sampled by uniformly interleaving samples along each edge.
--- Basic usage ---
Metro is a command-line tool which allows the user to select among different sampling schemes.
A list of the command-line parameters accepted by the tool is shown in the following.
Usage: Metro file1 file2 [opts]
where "file1" and "file2" are the input meshes in PLY, OFF or STL format, and opts can be:
-v disable vertex sampling
-e disable edge sampling
-f disable face sampling
-u does not ignore unreferred vertices and sample also unreferenced vertices
(useful for sampling point clouds against meshes)
-sx set the face sampling mode
where x can be:
-S0 montecarlo sampling
-S1 subdivision sampling
-S2 similar triangles sampling (Default)
-n# set the required number of samples (overrides -a)
-a# set the required number of samples per area unit (overrides -n)
-c save computed error as vertex colour and quality in two ply files
-C # # Set the min/max values used for color mapping (useful for taking snapshot with coherent color ramp)
-L Remove duplicated and unreferenced vertices before processing to avoid
-H write files with histograms of error distribution