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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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.
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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 ...
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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 ...
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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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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 ...
user4801
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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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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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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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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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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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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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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 ...
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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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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. ...
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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 ...
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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 ...
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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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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 ...
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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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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 ...
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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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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 ...
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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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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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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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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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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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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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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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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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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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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. ...
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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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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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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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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 ...
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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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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 ...
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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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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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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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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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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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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 ...
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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 ...
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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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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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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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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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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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