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Questions tagged [polyhedra]

84 questions
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Algorithm for randomly generating polyhedrons?

I want to randomly generate polyhedrons which need not be convex. What is the most efficient way for doing so? I can think of an algorithm for generating random convex polyhedrons, but am unable to figure out a way for generating non-convex ones.…
Aalok_G
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saving a geometry in postgis from blender

Say I have a cube or more complex closed triangulated object in Blender, how would I be able to store this in postgis? Postgis stores 3D geometry via well-known text (wkt) as a polyhedral or tin. Is there any way to get a blender object into…
Spatial Digger
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converting ply to postgis, script works but volume is invalid

I'm trying to convert a ply to a polyhedron stored in postgis. In this example I have a cube from 0,0,0 to 1,1,1 the script below brings in a geometry to postgis, it is there, no problem, however I go to calculate the volume and it gives the…
Spatial Digger
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Enumerating all basic feasible solutions

I want to enumerate all basic feasible solutions of a linear program. How can I do that with PuLP? I've read PuLP documentation, but couldn't find out how to do it. Your help would really be appreciated.
nemy
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Failing to extract volumes of difference between triangulated Nef polyhedrons derived from STEP files

Suppose to have a polyhedron representing an object A, and to want to get its concavities. An option for doing that consists in computing the convex hull CH of the object A and splitting the difference CH - A into connected components. For doing…
simonet
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PostGIS bounding pointcloud to polyhedral

I have a pointcloud which bounds a true 3D object, is there any way to go from this unstructured pointcloud to a polyhedral? Do I need to mesh/triangulate first? Does anyone know of a workflow and any functions to do this?
Spatial Digger
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why I get huge number in converting V-reresentation to H-representation in sage?

I have a set of vertices and I want to find a H-representation of them. I used sage to do that but I got weird number in the inequalities! here is my code: vert2 =…
sherek_66
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Overlap of Multiple 3D Irregular Polyhedrons in Matlab

I have a set of polyhedron each defined by a list of x, y, and z points. I would like to find the resulting polyhedron if I were to overlap the original polyhedrons together. I have used boundary(x, y, z) to find the bounding triangles of each…
user3315340
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Find the set of edges of a polyhedron, without duplication

I have a polyhedron which is defined by a series of vertices, which are vectors in R^3, and triangular faces, which are defined by a mapping of the three vertices which define the face. As an example, here is V and F V=[-0.8379 0.1526 …
shanksk
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DISTINCT clause used on non-distinct select error

I want to populate a drop down box using the one field from by data, I just want the unique values returned for a set of data from one table. Group by is not implemented in the polyhedra database I am using. Name is primary key for table and all…
user5410577
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How to compute the intersection between a convex polyhedron and another polyhedron?

The problem at hand is part of a scientific simulation concerned with 2D growth within 3D space. The 2D shape grows by adding (triangular) segments to the previously grown shape. Note that the actual segments in 3D have a thickness, thus, my code…
Merlin
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Three.js: how to create polygon/polyhedron?

Are there other ways to create polygon/polyhedron in three.js except this one? var polyhedronPts = []; polyhedronPts.push( new THREE.Vector2 ( -100, 600 ) ); polyhedronPts.push( new THREE.Vector2 ( 300, 600 ) ); polyhedronPts.push( new…
Somerussian
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CGAL::Polyhedron_3 demo - failing intersection

I started using CGAL demos to find the intersection of two polyhedra. I met a problem when the two polyhedra share some vertices and edges. The program extis with "Segmentation fault" call. I assume the problem refers to the shared vertices, since…
user3388750
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CGAL: minkowski sum along intersecting polylines

I've just started using CGAL to calculate the minkowski sum along a polyline - basically a 'glide' operation. There is a nice example of it here: http://doc.cgal.org/latest/Minkowski_sum_3/index.html#Minkowski_sum_3Glide Unfortunately, I run into…
mabl
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Exact formulae for the area of polygons and volume of polyhedrals

I want to compute the area of a random polygon and the volume of a random polyhedron. Google searches led me to tessellation and the Monte Carlo method. However I am only interested in an exact calculation and not an approximation through…
Aeronaelius
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