Questions tagged [3d]
Questions and problems dealing with three-dimensional space, including 3D meshes and other data structures, vector math, transformations, etc.
255
questions
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1answer
54 views
Motivation behind tesselation
This question is NOT about the hardware difficulties and shortcomings of tesselation shaders
I am trying to understand the motivation behind tesselation shaders.
Why/when/where tesselation is a good ...
0
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0answers
56 views
Is it possible that a superior, undiscovered 3D rendering method exists?
As far as I know, the only options we have for true 3D rendering are polygonal rendering, ray-marching and raytracing/casting.
Why is that? Surely there must be other ways? Is there some paper ...
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0answers
44 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 ...
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0answers
40 views
Proprietary 3D Format Reverse Engineering: What Could These Numbers And Matrices Represent?
I'm trying to reverse engineer a model format from an older Russian game (Pathologic) with limited success. It is a proprietary model format not recognized by any converters/editing tools (believe me, ...
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2answers
79 views
Why do OBJ files contain so many duplicate vertices if they use indices to define faces?
I have been experimenting with loading in OBJ files into memory using tinyobj. I have also been learning and analysing the OBJ file format specification. I have some code which loads the BMW car model ...
0
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1answer
42 views
How to ensure that a randomly-generated velocity vector moves the camera forward within a valid arc?
I spawn a camera in a scene using random coordinates for x and y and setting z=0 and orient ...
0
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1answer
79 views
How does 3D graphic software adjust for distortion inherent in perspective projection?
As this question and its answers point out, projecting a sphere on a flat picture plane, with perspective projection, may result in a ellipse, not a circle, and my understanding is that the only way a ...
0
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0answers
33 views
Calculating the intersection of two volumes
What is an efficient way to calculate the volume of intersection of two arbitrary volumes described as closed surfaces? That is, with two meshes, A and B, how do I calculate the intersection of A and ...
0
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1answer
87 views
How compute new camera parameters given a velocity vector?
My goal is to update camera parameters given a velocity vector so that the camera points in the direction of the velocity vector. How should one compute the update matrix for the camera parameters?
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0answers
24 views
Convert point clouds into voxels
I have points that are obtained by sampling a mesh(which is not watertight). Now, I would like to convert that mesh into voxel?
Does anyone have any suggestions for solving this problem?
2
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0answers
56 views
Why do materials have both an ambient color and a diffuse color?
One of the first things I learned about computer graphics lighting (and light in general) is that when a ray of light hits a surface, the surface absorbs certain colors and the light retains the rest. ...
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0answers
31 views
Is there a Performance Penalty for LOD objects with different topology?
I have a fairly complex-shaped object I've modeled, and in creating the LOD meshes, I've merged some verts, deleted some and even added some after in cases where this manipulation produced an n-gon. ...
1
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1answer
124 views
How do I extrude a 2D Bezier curve representation into a 3D solid using Python?
Where P is the control point, w is weight.
I plan to extrude this 2d representation into 3d. I have a discrete 2D representation (array which has [n_points, 2, 1] for each sample) of an airfoil that ...
2
votes
3answers
660 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 ...
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0answers
56 views
Quadric Edge Collapse Decimation of an object for reducing number of its vertices damages the original shape of object
I have been using "Simplification: Quadric Edge Collapse Decimation" for simplifying my meshes to only have ~800 vertices and it has been working with a couple of meshes I tried.
However, ...
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0answers
17 views
How to extrude a face from a selected mesh in Babylon,js using the ExtrudeShape method?
I'm trying to extrude a face from a selected mesh in Babylon.js using the ExtrudeShape but can't figure out why I got flipped faces.
The bottom extrusions always comes flipped for a reason I ignore.
...
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0answers
44 views
UV coordinates calculation broken
I've tried using the classic formula of calculating barycentric coordinates.
When the plane on which you are projecting the texture is collinear to any of the base vectors it crashes with a division ...
0
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0answers
21 views
How to draw a pdb 3d structure in webgl?
I am trying to create a 3d structure in webgl using 3d coordinates from a pdb file mentioned below: https://www.rcsb.org/structure/1RE2
I don't know which one is the appropriate one, so i used gl....
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0answers
17 views
Translate the camera with Pan gesture (when it is rotated )
I am new here
I am not good in math
SO what I need is I need to translate the 3D camera with Pan gesture on 2d Screen
With below code it is working
But if camera has some Euler Angle (rotated ) then I ...
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2answers
152 views
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0answers
41 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 ...
0
votes
1answer
16 views
Plotting points along a 3D line segment
I'm trying to plot some points along a 3D line segment and could really use some help. In 2D, I've found success getting the angle of the line, the sine & cosine of the angle, and then adding the ...
0
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1answer
225 views
What software was used to make KDA - Villain?
I want to try making small clips with realistic environment with the lighting in the KDA music video...
Any ideas what kind of program to use?
0
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1answer
47 views
Calculating Material/Texture Placement from Bitmap to 3D Model
everyone!
I am currently developing a program that converts a 3D model to 2D isometric pixel art. Part of my program extracts the texture from an FBX file (as FBX files can have textures built in), ...
2
votes
2answers
111 views
Why do some videos look smoother and others don't on the same monitor
I have a Dell monitor with 60 Hz refresh rate and therefore games playing on it are not very smooth as compared to 120 hz.
But when I open videos on YouTube of the same game on the same monitor, some ...
3
votes
2answers
149 views
Mathematical Foundations of Radiative Transfer
I'm new to learning about ray tracing, but have been fairly confused by the mathematical foundations of it all. Specifically of radiometry/radiative transfer. I've internet searched a lot and skimmed ...
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0answers
41 views
3D Bouncing Cube
I'm trying to write a little program with a bouncing cube but I can't find the right x, y, z and angle for it. I have these lines:
...
2
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0answers
57 views
Atmospheric scattering band/seperation artifact
I am currently experimenting with some atmospheric scattering in glsl in my OpenGL engine.
I am experiencing a strange phenomena where a strange band / separation artifact appears along the middle of ...
2
votes
1answer
61 views
How are obj files textured?
I am a new learner in 3d graphics. So forgive me if I seem to ask something very basic. I am confused how obj files are textured. So far I have seen:
obj + jpg
obj + mtl + jpg
When I look online, ...
1
vote
3answers
97 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 ...
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0answers
23 views
0
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2answers
79 views
What exactly is it about reality that is so difficult to recreate in a 3D simulation?
I have to admit that, while watching footage of the enhanced 2020 version of the 2018 game Forza Horizon 4, when they are driving fast, I have to sometimes remind myself that I am watching a video ...
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0answers
45 views
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 ...
1
vote
1answer
51 views
projecting 3d onto 2d plane is not showing up correctly
I am trying to learn about 3d graphics from first principles, so i have decided to implement a simple thing, create a circle in 3d space & rotate it along some axis. I understand the basics theory....
0
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1answer
304 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 ...
0
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2answers
90 views
Rounding a 3D corner with Subdivisions
Following the instructions from this post on Stack Overflow, I have been able to find points A, B, and C from points V1, V2, and V3 and a radius value (code below). I would like to be able to find a ...
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0answers
37 views
Retaining hierarchy of assembly when converting STEP to GLTF
I want to convert STEP files to gLTF.
I know that gLTF suuports hierarchy of assemblies and parts.
Source: https://cadexchanger.com/blog/283-how-to-load-3d-cad-data-into-three-js-part-2
However, it is ...
2
votes
1answer
70 views
Blend Shape, Pose Blend Shape, and Shape Blend Shape
Since there is a lot of cross-section between computer vision and computer graphics for 3D pose and shape estimation of non-rigid objects, I would like to know what "blend shape", "pose ...
1
vote
1answer
33 views
Real 3D interior room from 360 images
If I have 360 images of an interior room from all different angles, would it be possible with current 3D software technology to create a real 3D representation of that room, where the camera could ...
2
votes
1answer
381 views
Detect collision for non axis-aligned bounding boxes
in my application, I needed to detect collision between 2 3D objects. To make it simple I can represent a object as a bounding box. So actually the task reduced to detect collision between 2 boxes in ...
5
votes
2answers
121 views
How to decide which way to triangulate a quad?
Apologies if this is a dumb question... but given four arbitrary (non-coplanar) points in 3D space, there are obviously two different ways to triangulate the quad that they form. One triangulation may ...
2
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3answers
282 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 ...
0
votes
1answer
82 views
Is there a term for this sort of graphics?
I'd like to try to write some C code to create similar animated graphics to these, which are from a very old Commodore 64 game called "The Sentinel". I've been researching but I can't seem ...
0
votes
2answers
79 views
Shear(?) matrix projection along Z (depth) axis
I'm creating a primarily 2d game (platformer perspective) with 2d background parallax layers. The parallax effect falls out of the fact that I'm positioning a bunch of layers in 3d and using a ...
0
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0answers
46 views
Clipping 3D Perspective matrix
I am trying to implement clipping in my simple renderer, but i have a trouble with setting the boundaries. I used the same projection matrix that is in OpenGL. The problem is, the vertices that are ...
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0answers
55 views
What's a good research topic in Computer Graphics?
I am currently trying to find topics for my master's thesis. I would really like to do something in the field of computer graphics, but I've been having trouble finding what are some current problems ...
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0answers
30 views
Principal component analysis on 3d points and other ways of capturing variance
So, I would like to do capture on 3d pointclouds of 3d models the planes/vectors where for each object we have the highest variance (i.e. for object represented by 2000 3d points I would like to get ...
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0answers
47 views
What modern C++ Unit Testing Framework do you use for highly parallel image, 3D and higher dimensional matrix processing workloads? [closed]
Most of the existing open-source libraries such as OpenCV, Tensorflow, and Pytorch use Google Test. I would like to know about strong alternative testing frameworks that thrive under a similar ...
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0answers
35 views
How to transform x-y-z red-green-blue arrows and draw them on 2D screen?
I'm making a raytracer and want to print debug arrows
Blender example:
Old version of 3d max:
How do I do the same having camera forward, up and right vector?
I think I need some kind of matrix ...
2
votes
0answers
72 views
Implementing monte carlo path traced refractions problem
I am writing a forward monte carlo path tracer with the added feature of specular refractions for transparent materials, I have managed to come this far but something is not quite right and I am ...
