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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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1 vote
1 answer
36 views

Vertices are mapped to UV coordinates, but how does the shader access the UV data?

So in every mesh, the vertices can have UVs, and UVs are a way to store data for each vertex. Basically, at the time of rendering, when the shader runs, it's a way to check some arbitrary data for ...
3 votes
1 answer
803 views

Difference between a spherical camera and a trackball camera

A spherical camera is pretty easy to define. We have an anchor point C the camera always looks at and a relative position P where the camera is, which can be expressed in spherical coordinates, ...
1 vote
0 answers
26 views

How to morph a enclosing mesh according to the enclosed mesh?

I am quite new to meshing and mesh manipulation. I am working on a problem consiting of meshes $A$, $B$, and $C$. The mesh $C$ completely encloses the meshes $A$ and $B$ as shown in the attached ...
0 votes
2 answers
196 views

how to check if all the faces face outward

Situation: I am using Open3D python,The mesh generation algorithm ( like ball pivot, poisson reconstruction ) are dependent on normal direction. I used ...
1 vote
1 answer
141 views

Constructing half-edges table from triangle list without hash

Motivation I am trying to refine a mesh such that each triangle gets subdivided into 4 triangles, but I want the vertices to be shared. For that purpose I need a half-edge data structure so I can ...
0 votes
1 answer
61 views

Create a tight frustum around a 3D model bounding volume

Tight frustum I intend to create a tight frustum around a 3D model: I have these variables: Inputs: 3D model bounding box or bounding sphere or bounding volume. To be determined: Eye distance and ...
0 votes
2 answers
116 views

How to extract region inside a loop on sphere

The input is a sphere(defined by radius and center) and a loop defined by a set of points(unordered, illustrated in cyan in the image above) that satisfy the implicit function of the sphere. How can I ...
0 votes
1 answer
1k views

Rotation of meshes in PyTorch

I am doing some project on object reconstruction and I need to rotate an object in PyTorch during the training to make sure I am augmenting the data properly. My data consists of points and it's ...
0 votes
1 answer
152 views

Procedural generation of genus $k$ tori triangle meshes

I am looking for code or pseudo-code for the generation of genus $k$ tori triangle meshes. I want to get something like in the image here. Book/paper references, code, github links, etc. are all ...
1 vote
0 answers
64 views

Piecewise smoothing of a mesh?

Kobbelt et al. published a paper some 20 years ago where they specified how solving Poisson equations on the positions of a mesh lead to removing noise. This can be used for reconstructing mesh ...
0 votes
0 answers
111 views

Can STEP files contain polygon data? How do I get a smoother mesh out of a STEP file?

I am trying to work with a .STEP file I have received. Upon opening it in CAD Assistant, I find its surface as jagged lines, like a low poly model. When I export it as OBJ from there, the edges and ...
0 votes
0 answers
63 views

How can I understand the logic of Fast Point Feature Histograms (FPFH) descriptor?

I have been using FPFH features quite a lot in global registration and key-point extraction a lot, I also looked pcl page that tries to explain what it is, but fails to give detail to reader in my ...
0 votes
0 answers
46 views

How to transform face mesh?

We can use ARcore to create custom textures and 3D models for Augmented Faces, like the augmentation of a Fox ears. But aside from augmenting 3D objects, can we "transform" facemesh, for ...
1 vote
0 answers
52 views

How to find point on mesh at a minimum distance from ray

I'm searching for an efficient data structure and algorithm to compute the minimum distance between a ray and a set of meshes in 3D. What I expect as a result are the coordinates of the nearest point ...
0 votes
1 answer
38 views

How to measure distortion of a parametrization?

If you have a map from a mesh into the 2D plane. How do you measure its distortion? I know that theoretically what you do is express the differential map of the transformation then use SVD to figure ...
0 votes
0 answers
24 views

Volumetric mesh processing: impact of facet removal on connectedness?

I am working with volumetric meshes - meshes that have vertices (0-cell), edges (1-cell), facets (2-cells) and volumes (3-cells) - and I'm interested in removing facets without breaking connectedness. ...
0 votes
0 answers
86 views

Floating point precision in 3d modeling software

I'm working on a simple 3d modeling application. I'm using 1 meter as unit of measurement. When working with small triangles where an edge length is around 1 centimeter (0.01 units) or less, I started ...
1 vote
1 answer
215 views

How to get the accurate number of triangles of an wavefront obj model?

I am confused by a 'wavefront obj' file's true triangle number. For example, I downloaded the Rungholt scene from McGuire's Computer Graphics Archive. ...
1 vote
0 answers
86 views

LOD/culling algorithms with procedural meshes

I am experimenting with procedural meshes. Those are generated at runtime in a compute shader. I'm getting to the point where those geometries are big enough to require some sort of culling/LODing ...
0 votes
1 answer
57 views

What technique can I use to swap thousands of models per frame?

I need to render a lot of objects that swap their model from frame to frame. Currently, I am putting every model into a single vertex buffer and giving every vertex an id. I store the same id in the ...
0 votes
0 answers
69 views

How would you represent a mesh with tris and quads?

My understanding is that, while subdivision algorithms like Catmull-Clark can work for any polygonal mesh (including triangles) it's preferable to start with a quad mesh. Currently my rendering engine ...
2 votes
0 answers
53 views

Stitching 2 boundaries together

Let us say we have 2 boundaries of 2 meshes that are roughly aligned, for example 2 generalized cylinders (sweeping surfaces) with a small gap in between. And let us say we want to connect them to ...
4 votes
2 answers
2k views

What is the difference between a "meshlet" and just a small mesh?

Obviously, conceptually, a meshlet is just a small mesh. But what is the reason for making the distinction then? I'm assuming it has to do with how they are implemented. In a meshlet architecture, ...
2 votes
1 answer
146 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 ...
1 vote
1 answer
192 views

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
213 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 ...
4 votes
1 answer
522 views

Algorithm to map a triangular mesh onto plane preserving angles and distances from one vertex

I have a 3D triangular mesh representing cortical surface of a brain. I also have one vertex of interest. I would like to unfold a neighborhood of this vertex in such a way that both the angles (their ...
14 votes
2 answers
24k views

Programmatically generating vertex normals

I'm working with Kinect face api, it provides an array of vertices and indices for triangles which is to be rendered to make the face image. The no of vertices and their order in array as well as the ...
1 vote
0 answers
41 views

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.
32 votes
2 answers
25k views

What is the simplest way to compute principal curvature for a mesh triangle?

I have a mesh and in the region around each triangle, I want to compute an estimate of the principal curvature directions. I have never done this sort of thing before and Wikipedia does not help a lot....
0 votes
1 answer
217 views

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 ...
4 votes
1 answer
2k 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 ...
0 votes
0 answers
40 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 ...
1 vote
1 answer
356 views

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 ...
4 votes
0 answers
616 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 ...
3 votes
1 answer
830 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
153 views

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 ...
0 votes
1 answer
712 views

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 ...
0 votes
1 answer
3k views

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: ...
1 vote
0 answers
26 views

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 ...
1 vote
0 answers
118 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 ...
1 vote
1 answer
59 views

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 ...
2 votes
1 answer
100 views

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 ...
1 vote
1 answer
184 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
72 views

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 ...
1 vote
1 answer
102 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 ...
0 votes
1 answer
230 views

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 ...
4 votes
3 answers
12k 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
0 answers
150 views

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 ...
1 vote
1 answer
107 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 ...