Questions tagged [mesh]

Questions about a network of connected vertices, edges and faces to describe the shape of a specific 3D object.

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Best way for rendering Voronoi diagram from Delaunay graph mesh

I have a set of points, which I triangulate to a Delaunay graph to make a mesh. Every mesh vertex has a unique colour, and I can render it without any problem. But I want Voronoi rendering to be ...
2 votes
1 answer
31 views

How to create a mesh from a skeleton?

Say you have a topological skeleton, you want to fabricate a mesh out of it, what algorithms exist to accomplish this? I know of at least one way, which is to represent each edge as an implicit ...
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What design pattern should be used for undo/redo operations in modeling software

There are multiple ways to implement undo/redo functionality. One is using memento pattern, where you store the state of the object before running each command, and then the undo action means rolling ...
2 votes
1 answer
47 views

Inspecting gltf animation data

I am trying to load gltf data onto an engine I am making and I am noticing that something is wrong with the rotations. I want to be able to see the raw numeric values of the animation data in the gltf ...
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1 vote
0 answers
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Geodesic triangle strip algorithm

I think somewhere in the literature there is an algorithm that, given 2 points on a triangle mesh, finds the triangle strip through which the geodesic passes, but I cannot find it anywhere.
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4 votes
1 answer
699 views

How to calculate volume of any given 3D mesh

Given 3D mesh with a closed surface. (solid object without hole). I'm looking for an algorithm to calculate its volume. There are several ideas, Such as Voxelized and count voxels Point cloud and ...
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Computing vertex normals in mesh triangle soup

I am using c++. I have to find vertex normal in mesh. The mesh is triangle soup. The winding order is inconsistent. I know that it is the sum of all faces normals arround the vertex. But I don't know ...
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27 views

How can we represent a self-intersecting surface without analytic expression in computer?

Suppose we have a suface without self-intersection, then we can store it numerically using grid samples from its signed distance funtion. But what for the self-intersecting case, can we still use the ...
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Render face AR effects using Mediapipe and ARKit in one app

I am creating app to render AR face effects, like tattoo or make-up or 3D glasses. For Android I would like to use Mediapipe Face Mesh (https://google.github.io/mediapipe/solutions/face_mesh.html) and ...
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How images are represented in 3D space?

Many 3D graphics libraries like OpenGL model 3D objects like cube using a set of vertexes and 3D triangles. But I am wondering how images are modelled in 3D space so linear transformations can apply. ...
1 vote
1 answer
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3D head mesh morphing from one mesh into another using coding

I have 2 3D head images and want to morph one into the other (animation) without using blender etc. I want to do it using coding preferably using C++, C# or python(libraries are ok). I have done 2D ...
3 votes
0 answers
90 views

Watertight Mesh Representation

A watertight mesh is one which does not have holes, and for which each face has a designated inside and outside. Such a mesh can be "tetrahedralized", has a defined volume, and can be an ...
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Explanation for the brute force ray marching method

Hellos, I am new to raymarching and 3D and I use python for my coding. I am trying to make a engine for raymarching and was finding the signed distance function for a mesh. How can I get a signed ...
3 votes
1 answer
250 views

Smooth triangular mesh interpolation

I am looking for an algorithm which would smoothly interpolate triangles of a mesh (computed by Delaunay triangulation) where each vertex has some value (elevation in my case). I need it for PDAL ...
0 votes
1 answer
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Why the Bowyer's version and Watson's version of computing the Delaunay tessellation are equivalent?

Bowyer–Watson algorithm might be the most famous method for computing the Delaunay triangulation of a finite set of points in any number of dimensions. Its Wikipedia page and most textbooks on ...
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Are there English translation of Voronoï, Georges's two papers on Voronoi diagram?

1.Voronoï, Georges (1908a). "Nouvelles applications des paramètres continus à la théorie des formes quadratiques. Premier mémoire. Sur quelques propriétés des formes quadratiques positives ...
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1 answer
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What's a simple way to find connected components in a mesh?

As stated I have a triangle mesh I want to separate into connected components. One way I would assume would be to do a depth first search on a vertex and remove vertices, then repeat until the set is ...
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1 vote
0 answers
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Geodesic approximation algorithms for minimal geodesic curvature

Introduction I am building an application in which given a surface and a pair of points on it, an analytic expression of some geodesic arc (preferably the one with the shortest length), between them ...
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Mesh simplification

I want to simplify the mesh (eg reduce the number of polygons) for optimization. There are many simplification algorithms, how to find out for which model one or another algorithm should be applied? ...
1 vote
0 answers
75 views

Given a mesh, a point on the mesh, a direction and a distance, compute the face+barycentric coordinates of point at that geodesic distance

I am a beginner at graphics. I am given a triangular mesh (assume a manifold mesh). I want to sample a square on a mesh that is independent of the triangulation. I am following these steps Sample a ...
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1 vote
1 answer
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Extrude from line and find intersection points

Hey Im currently learning about geometry and vectors and was trying to build a room builder with three js. I basicly create walls from two points (p1, p2). I draw a line and extrude the line to a ...
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2 votes
1 answer
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Does automatic UV unwrapping work with an indexed face set model?

When working with Graphics APIs like OpenGL its common to use an index face set model. That is, multiple faces share adjacent / overlapping vertices by using a list of indices. Most game engines like ...
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1 vote
1 answer
109 views

What does an algorithm which handles mesh-based image morphing look like?

In recent years, the technology of Live2D has become particularly popular and I have been attempting to find any papers or articles which explain what the mathematics for the mesh-based image morphing ...
0 votes
0 answers
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ray triangle mesh intersection triangles inverted

I'm trying to render a dodecahedron triangle mesh and the triangles seem flipped or mirrored somehow. The first picture is what I should be getting, the second picture is what I'm getting and the last ...
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0 votes
1 answer
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Are vertices of each LOD version always loaded into VRAM

Are vertices of each LOD version always loaded into VRAM? I know many game engines have a LOD feature for mesh vertices and textures. I'm just wondering if all vertices and textures of all(each) LOD ...
1 vote
1 answer
75 views

How to map texture pixels to the corresponding 3D positions?

I have a mesh stored in .obj format with a texture image in .png format. For any "defined" pixel in the texture image, I'd like to compute the corresponding 3D coordinates when the texture ...
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Methods to interpolate between 2 topologically identical 3D meshes

I have 2 3D surface meshes. These meshes have vertex-correspondence and have the same topology (same edges and triangles connecting the vertices). However, the vertex positions (3d coordinates) are ...
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Cad ingesting SDK that supports STEP , Parasolid and Solidworks filetypes and Also Meshing

We have an internal CSG (Constructive Solid Geometry) format.Converting/Ingesting other CSG-based files to our internal format is straightforward. We also managed to convert some polygon (mesh) based ...
2 votes
1 answer
82 views

Catmull–Clark issue with plane corners

I implemented catmul clark based on this Wikipedia article. And it seems to work fine for meshes where the edge point count is equal to the face point count, but not for planes where the corners have ...
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Is there any open source code available for simplification of tetrahedral mesh?

I am currently working on tetrahedral meshes and I want to downsample the mesh using techniques like Qslim but there is not much about tetrahedral meshes in the literature. I try to use it as a ...
3 votes
3 answers
6k views

How can I get a signed distance (SDF) from a mesh?

I am trying to use constructive solid geometry (CSG) and boolean operators to combine various shapes and get the outer (possibly concave) hull. This seems to work okay when using primitive shapes like ...
0 votes
1 answer
41 views

Computing heat diffusion creates weird results

I am trying to model heat diffusion on the surface of a mesh. I annexed the most important bits of theory about this topic as screenshots on the question see the bottom. The crux of the issue is we ...
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2 votes
0 answers
52 views

Divide mesh according to level of detail

Background I need to remesh by OpenVDB, like what Blender remesh does: Voxel Uses an OpenVDB to generate a new manifold mesh from the current geometry while trying to preserve the mesh’s original ...
6 votes
1 answer
97 views

Existing method to automatically fill in this sort of concavity in meshes?

I am working with a PWP3D-like algorithm that renders silhouettes of a mesh in order to segment a frame of video and update an object's pose. Because it is only the silhouettes of the mesh that matter,...
0 votes
0 answers
75 views

How can I render a triangle mesh at 10bit (or 12bit or 16bit) channel depth color?

For a vision research experiment, I have a monitor that supports 10bit/channel (=30bit color). I want to render a triangle mesh in a simple scene that uses the full bit depth, and I want to save this ...
0 votes
0 answers
44 views

Under what conditions does a mesh operation cause the mesh become non-manifold and how to avoid it?

I'm implementing some mesh operations (e.g. edge collapse, edge split, edge flip etc) and need to ensure applying such operations does not cause the mesh to become non-manifold. However, I'm not sure ...
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0 votes
1 answer
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Differential or intersection of islands of 2D polygons in different layers

I have a 2D layer/section containing the 2D polygons colored in shades of green. I have another layer containing the 2D polygons colored in shades of blue. I intend to figure out how different are ...
0 votes
1 answer
28 views

Render Duplicate Miniature Scene Replica

Context I am working on project for implementing and user test a World-in-Miniature (WIM) interface for VR. A WIM essentially is a replica of the scene the user is currently in, but in miniature. ...
1 vote
3 answers
156 views

Silhouette below 3D model

There are some 3D applications which can cast shadow or silhouette below 3D models. They render pretty fast and smooth. I wonder what kind of technology is the standard procedure to get 3D model ...
0 votes
0 answers
45 views

Calculating minimal voxel size in a mesh

I am developing a script that will determine a minimal voxel size in a mesh. My first thought was to caculate the area of given face. Another approach would be to calculate minimal line length and ...
1 vote
1 answer
88 views

Is There an algorithm to remove intersections between two tetrahedrons?

I have a mesh made up of several tetrahedrons, I know for sure that there are intersections between some of them: how can I remove these intersections, without generating others? In other terms: if ...
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0 votes
0 answers
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Algorithm to select regions based on curvature on a mesh

I'm trying to understand how to implement an algorithm similar to the one used by Magics' mark surface tool, you can see such behaviour on this video. Quoting the video: "Basically with this tool ...
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2 votes
0 answers
42 views

Wrapping a point cloud skeleton with a mesh

Using Unity I've been producing sculptural forms that look like this. It's made of patterns of cubes that twist around each other. I'm trying to get it into a 3D printable format. From unity I export ...
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2 votes
1 answer
368 views

Tetrahedron orientation

I am developing a software that needs to interact with a mesh processing program, using tetrahedral meshes, however I am finding difficulties in this. The program requires all tetrahedrons to have ...
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0 votes
1 answer
615 views

Vertices, Vertex Normals and Face Normals

Using Open 3D Model Viewer, I have converted an OBJ file to an STL file. In the source file, the Vertex Normals are specified and in the destination, the face normal of the triangles are present which ...
2 votes
1 answer
143 views

What's the simplest, open, animation format?

I have an obj parser that handles triangle meshes specifically. I want to extend it (and the rest of my system) to handle animations as well. However, I don't think I am ready to tackle the glTF ...
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0 votes
1 answer
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Drawing a cube and wireframe opengl

I'm trying to render a cube and it's wireframe together using OpenGL The main function is this: ...
3 votes
1 answer
138 views

Why is the valence of regular vertices 6?

So I recently learnt that supposedly for any mesh, and pretty much any scheme, the valence of regular vertices must be 6. It seems to be related to the Euler-Poincare formula but I have not been able ...
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2 votes
1 answer
73 views

Sort half-edges around common vertex in 3d [closed]

I'm trying to figure out this problem for very long time and am no getting nowhere. I'm working on a simple 3d modeler that uses half-edge data structure. Say I have non-manifold geometry where two ...
3 votes
1 answer
62 views

Mis understanding of the Heat Method

I have been trying to understand a paper in CG for a while, called the Heat Method by Ken Many things have clicked but I don't fully understand it yet. In particular. In the following $u$ is a vector ...
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