Questions tagged [mesh]

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1answer
30 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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0answers
17 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 ...
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1answer
47 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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1answer
48 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: ...
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1answer
48 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 ...
2
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1answer
34 views

Sort half-edges around common vertex in 3d

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
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1answer
37 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 ...
3
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1answer
35 views

Algorithm for constructing doubly connected edge list in 3d

This post explains how to construct double connected edge list in 2d. One of the steps in the algorithm is to sort the halfedges around a vertex in clockwise order. However this will not work in 3d. ...
4
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1answer
48 views

Gradient descent (Not ML) on arbitrary meshes

So I am doing a gradient descent like algorithm on the surface of a mesh and I just noticed something: The above is the geodesic gradient (the distance to a single vertex) Look at where the ear ...
2
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1answer
30 views

Wondering if it's possible to 'extend' a texture beyond the mesh without altering the mesh itself

I'm in Blender and working with a pre-existing 3D model- I want to add more length to it, but I don't want to mess with the mesh- Is it possible to extend the texture beyond the mesh without changing ...
2
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3answers
64 views

How to Sample 3D Points Outside and Inside the Mesh Surface

I have a mesh of an object enclosed in unit volume cube and I would like to sample points inside and outside the mesh surface. What are the different ways of doing it? Is there any sample code ...
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1answer
38 views

Calculating the gradient of a tetrahedral mesh

How can I compute the gradient for a tetrahedral mesh (3D)? For triangular mesh, I got an answer from the following post Calculating the gradient of a triangular mesh How can I get a similar formula ...
2
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2answers
110 views

Smart half edge iteration?

In my HE implementation, half edges are stored in an array. When I iterate over the edges, I color all the HE black, and when I do an operation on an edge (e.g edge splitting) I mark both the current ...
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0answers
32 views

What method is used for baking grayscale curvature maps

I'm looking for a way to generate curvature maps like this: The map stores the Convexity and Concavity of each pixel as a value from 0 to 1, where .5 is no curvature and 1 and 0 are the extremes. I ...
2
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1answer
44 views

How do you apply a normal map to a 3d mesh?

I'm writing my own mesh renderer, and I previously was able to apply a normal map to a sphere, so I understand the basic process of applying a normal map. But my understanding is that in order to ...
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1answer
38 views

Fast and exact Geodesics on meshes, Backtracking confusion

The following is an excerpt from a 2005 paper on geodesics on triangular meshes, taken from section 3.5 In this case $p$ is a point on some arbitrary face in a mesh, $p'$ is a point on one of the 3 ...
4
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1answer
100 views

Reducing artificial rings in mean curvature of mesh

I have an isosurface/mesh (generated via marching cubes) of a micro-CT scan. Originally the surface looks very noisy, which becomes prevalent when the mean curvature is visualized: To reduce the ...
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0answers
25 views

MMP Geodesic algorithm I need clarification

I am reading the 1987 paper on Geodesics on polyhedra and I am confused on something. The paper states: If $I1==NIL$, the channel is simply that part of $f’$ to the left of $\beta_2c_2$; and if $I2==...
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1answer
48 views

Finding geodesics on a mesh?

What are some state of the art methods/algorithms to find geodesics on arbitrary manifold meshes?
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1answer
51 views

How to use PCA to reconstruct 3D Mesh?

Given a set of human body mesh {S_i}, for each S_i, the points are N*3, we can do PCA on that. We can use PCA to reduce the dimension of {S_i}, for example to k dimension. Let the main direction of ...
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1answer
45 views

chess-like rectangles on the mesh

I am new to concepts in CG. What are the red and white rectangles trying to represent in the following screenshot? The image is from the paper "MoSh: Motion and Shape Capture from Sparse Markers".
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1answer
71 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 ...
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2answers
88 views

What tris and quads need for?

I know that 3D artists make a 3D model with quads. And they advise to remesh with quads only (if it's possible). So I have some questions: Why do we use quads in CG (for games, cartoons, film, etc) ...
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0answers
47 views

Problem calculating tangent space

I am currently writing a 3D rendering engine for educational purposes. In general everything is working except that I am chasing down a problem in my cube mesh / tangent calculations that I can't find....
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2answers
144 views

Calculate normals from vertices

Assume you have a list of vertices and their connectivity information. (I.e you can find all the adjacent edges and faces to each vertex). What is a good approach to calculate a normal from this ...
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0answers
14 views

What algorithms are needed to map displacement to base mesh?

By given belows, Base mesh(vertices, faces, texture coordinates - UV map), Normal map(1024x1024 image), Displacement map(1024x1024 image), I want to make a mesh which reflects the displacement map. ...
1
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1answer
88 views

What is the reason that a boolean operation between two almost identical 3D triangular meshes fails?

I have been trying to detect defects on "before-and-after" meshes, by finding the boolean difference between them, to no avail. I tried these two Python libraries(algorithms run in C++) but their ...
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1answer
41 views

Looking for a compact file format for outputting 3D geometry with color support

I am looking for a file format to output some 3D geometry. In my case, it only needs to handle very simple shapes - uniformly spaced and sized cubes at points in space. So far I've ended up just ...
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0answers
28 views

Loop subdivision, certain areas converging towards degenerate geometry

I coded loop subdivision and ran it on a cube with triangle faces. I noticed this: I am using doubles to represent my vertex positions, I am not 100% sure these are caused by floating point ...
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0answers
58 views

Mesh boolean and amount of triangles

Inspired by BSP tree mesh operations, I've implemented an operation that takes a mesh X, a BSP tree/sequence of planes, and creates a new mesh, by iteratively slicing mesh X by these planes in some ...
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0answers
16 views

Turning layered curves to polygon mesh?

I am confronted with the problem to render 3D representations for objects marked on microscope slices. So I have a set of aligned polygons in parallel planes from tracing the outline of the object in ...
2
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1answer
52 views

How to subdivide faces with a half edge DS?

Assume we have a mesh represented as a half edge datastructure. We want to subdivide faces without introducing unnecessary vertices (i.e the new number of vertices must be exactly V + E where V is the ...
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0answers
22 views

Algorithm to reproject texture after wrapping mesh using ICP?

I was watching this video, where given a base mesh we wrap it in a scanned mesh, I can imagine how to implement something similar from scratch, but I was wondering how can I assign uv coordinates to ...
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0answers
41 views

Find the inside and outside relationship of connected components in a mesh

I extract a mesh from a method similar to Marching cubes. I want to estimate the topological relationship between connected components. For example, below, let's assume that we have 4 connected ...
4
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1answer
88 views

Saving a mesh and textures into a single file

I'm looking for a format where I could store a triangle mesh and multiple textures into a single file. Most formats only reference an external file for textures. I found that the FBX format should ...
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0answers
49 views

Bounding box of a rotating mesh

I compute bounding box of a mesh: (xMin, xMax) (yMin, yMax) (zMin, zMax) To get the bounding box, I need to go through all the mesh points and compute the min/...
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1answer
55 views

Generating the end caps of a cylinder using triangle strips for use in a geometry shader

I know how to generate the walls of a cylinder with triangle strips and the caps with triangle fans, but since I am working inside a geometry shader, I can only output triangle strips, so I am kind of ...
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0answers
37 views

Algorithms used in Wrap3?

I've just downloaded Wrap 3, and I'm playing a bit with it. I can't find any documentation about the specifics geometry algorithms used in the software. Does anyone happen to know where I can find a ...
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0answers
60 views

Apply transformation to single vertices in OpenGL in order to deform mesh

I'm making a 2D cell simulation game. The mesh for my cell is basically just a manually-generated triangle fan that looks like this. I would like to reproduce the wobbling/vibration effect on the ...
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0answers
36 views

Question about simple estimation of the discrete curvature at vertices of a mesh

In this post, Nathan-Reed gave a simple, neat, "heuristic" estimation for the discrete curvature at vertices of a mesh. In a nutshell, it computes a curvature along each edge incident to the vertex, ...
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0answers
26 views

Apply a pose to a 3D model/mesh

Assuming that I have pose information for a human, is there any ways/tools to apply that pose to a 3D model? Basically, given continous pose information say from a dancing person, I like to animate a ...
1
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1answer
39 views

Calculating normals for vertices which aren't a vertex of all neighbouring triangles

In my procedurally generated mesh in Unity, not all vertices are vertexes of all neighbouring triangles - essentially, it's a grid with cells of varying sizes. This is messing up the calculation of ...
4
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2answers
94 views

Creating a Smooth 3D Mesh from a 2D Outline

I am trying to find (or maybe create) an algorithm for creating a smooth, rounded 3D mesh given a 2D outline. I'm trying to recreate a system from a Gamecube game called Amazing Island, and you can ...
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0answers
57 views

How to render multiple shaders per mesh

I've tried looking everywhere, but I just don't get it. How is multiple shaders assigned to a mesh if you can only bind a single shader in OpenGL? Assume I have a mesh with a texture shader and now I ...
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0answers
34 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, ...
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1answer
44 views

Stecklov operator vs Laplacian operator

There's one paper published at siggraph that captured my attention : Steklov Spectral Geometry. I'm not an expert in geometry processing, but I'm trying to learn as much as I can. You can easily read ...
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1answer
93 views

What is performance better - add four materials to mesh or duplicate every vertex and use packed texture?

I am making ski jumping game (in Unity) with procedurally generated hill mesh. I want to add lines on hill like this (mesh is created by script, but I've manually assigned materials in Blender) ...
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0answers
28 views

Boundary Smoothing Algorithms

I have a 2-manifold with boundary, built with marching cubes. Are there any well-known algorithms for smoothing its boundary edges? Most of the papers I found are concerned with smoothing the surface....
0
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1answer
124 views

Pseudo rounded cube in OpenGL

If I have a cube in OpenGL, how can I have it appear like rounded? I think it's too complicated to really have the cube rounded so is there any "light trick" to have something like this: The cubes ...
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0answers
91 views

Application of parallel transport in computer graphics and mesh processing

Does anyone know what applications has the computation of a parallel transport on a mesh? I'm talking about methods such as this one