Questions tagged [3d]

Questions and problems dealing with three-dimensional space, including 3D meshes and other data structures, vector math, transformations, etc.

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6 views

How can I detect if an edge has flipped during the UV unfold process?

I'm writing my own UV Unfold operation (similar to Maya's Optimize UV tool or 3DS Max's Relax Tool). My code works great 90% of the time but in some instances, I'm getting faces and edges that flip ...
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41 views

Help with understanding the look-at function (the view matrix)

I've been reading this article about the look-at function. I don't understand the part when they're trying to inverse the matrix N. They say that R is orthogonal because all its row and column ...
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19 views

How do I automate projecting a 2D vector image onto a 3d curved surface plane? [closed]

I am creating a workflow consisting one or more tools to wrap or project 2D vector images onto a 3D surface plane. The process is as follows: Convert image in a vector format (any format compatible ...
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1answer
71 views

How can i create a 3D Sphere(earth) using OpenGL, GLFW, GLAD, GLM?

Please help me out with this thing and currently i am a little more than a beginner so please tell me in that context. i don't need any obsolete methods for creating this like using GLUT or GLEW.can ...
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1answer
4k views

How to derive a perspective projection matrix from its components?

This has been haunting me for several days now. I want to find the component that makes up of this 4x4 perspective projection matrix, with $l$(left), $r$(right), $b$(bottom), $t$(top), $n$(near), $f$(...
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2answers
265 views

Was Evans & Sutherland CT5 really created in 1981?

A few days ago I found a video on Twitter showing the Evans & Sutherland CT5 Flight Simulator system. It was labeled as 1981 footage and looked really amazing. The first time I saw similar 3D ...
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2answers
88 views

Programmatically generating bin files for GLTF models

I have a need to generate a series of GLB files. I have a base template for a GLTF file which I have to derive off of. The models thus generated will only have varying textures on them. The base mesh ...
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1answer
49 views

What are the i,j,k components of a 3d mesh on plot.ly (online)?

A 3d Mesh on plot.ly online graph maker (https://plot.ly/create/#/) takes 3 mandatory variables (X, Y, Z) and 3 optional variables (I, J, K). I understand that if I want to draw a cube that I then ...
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1answer
57 views

Vulkan: efficient way to update VBO mesh vertices?

I would like to change/add/remove some mesh vertices in existing VBO's (while deforming and remeshing 3D objects) . With OpenGL I would have to reload whole vertex VBO's. I suppose with Vulkan there ...
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19 views

Newby - which computer language for video to video &/or 4-D to video

First post on forum. What's the simplest language / package for computer graphics that will do what i need? I have two projects in mind: One is to input a video (eg. from youtube) and process it ...
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80 views

Why don't I see tile-based 3D graphics?

As we know, tiles can make it quicker to update large portions of the display at once, as compared with a bitmap. To put, say a letter, on the screen, the Commodore 64 typically does two writes (the ...
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55 views

Using octree for cheking intersection of ray and meshes

I wrote the code for checking intersection of ray and meshes on scene. It consist of two parts - broad phase and narrow phase. In broad phase I build an oriented bounding box around each mesh and ...
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1answer
43 views

Export Model Textures Per Face

(Note that as far as attempts go, I can't find anything that helps me) I have a 3D polygon, and for simplicity's sake it's going to be the one below: It is textured using the UV map below: Side ...
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58 views

Programmatic rendering of 3D animations

Many years ago I used POV-Ray to render some 3D animations. I liked POV-Ray's Scene Description Language (SDL) as I could generate the required files programmatically using other languages (e.g. Perl)...
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1answer
56 views

Rendering 3-D point clouds obtained from depth maps as a 2.5D video

Suppose I have code to generate a bunch of frames, each of which is a depth map(I have access to the matrices which represent depth) which in turn is used to generate a point cloud. One frame would ...
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1answer
96 views

qt - view geomview (.off ) file

I want to open a .off file and view the content 3d model using libQGLViewer, qt-creator. I don't know how to display the 3d model after opening its .off file. ...
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2answers
204 views

3ds max: Z-fighting when working with Large Objects

I had a z-fighting/z-clipping issue with a scene containing some very large objects yesterday in 3ds max. It can be seen in the image below: For some reason downscaling the scene significantly (a ...
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4answers
1k views

How to build a 3d model from 2d pictures

I have a series of MRI images. I want to build a 3D model out of it, which not only presents the surface, but also contains the inside structures. What kind of photogrammetry based method can realize ...
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2answers
155 views

Unfold a 3D mesh to a 2D plane

I'm trying to unfold a 3D mesh onto a 2D plane. My general idea to do this, would be to cycle through all the faces of the meshes and perform a hierarchical transformation. So I would start at the ...
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1answer
127 views

Why do animated CG characters always feel fake?

Why do animated CG characters always feel fake? Usually if a CG character is an animal (or humanoid creature), they tend too look kinda off. Their movement tends to look oddly smooth or lightweight, ...
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2answers
101 views

transformation from cartesian coordinates to spherical coordinates without calculations

Given this graph in the 3d cartesian coordinates i should figure out the spherical coordinates representation but without the use of calculations . I've been trying to solve this the whole day but i ...
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1answer
29 views

Can you generate your own HDRI maps without using photos?

For example, preparing a scene in Maya using standard lights and rendering out a panorama? Could they also be made from scratch in photoshop using 32bit color? Is there a reason why people don’t ...
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0answers
52 views

Intersecting Frusta

I am trying to determine whether two frusta intersect in 3D space and to quantify this intersection as a percentage of one frustum volume (eg. 100% intersection meaning that the two frusta occupy the ...
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1answer
54 views

If you can use subdivision surfaces for 2D curves

I've seen how subdivision surfaces are good for 3D curves/modeling, but haven't seen anything on if it's good, or even usable, in 2D. My question is just that, if (a) you can even use subdivision ...
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1answer
65 views

Problems with Subdivision Surfaces

It sounds like Subdivision Surfaces are better than NURBS but not as good as T-splines. I would like to know some of the disadvantages of Subdivision Surfaces, what they can't do or what they do ...
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0answers
37 views

Convex hull around polygon for cave mapping

For the purpose of mapping caves, we survey new passages so that we take main polygon (survey from point A to point B) and on each "node" (survey station A in example), we shoot multiple "splay shots" ...
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2answers
156 views

How to get the 3D position for the point with (0,0) UV coordinates?

I have a 3D triangular mesh(vertices, indices, uv coords) that I'm rendering to the screen. Let's assume that the UV mapping is one-to-one. I'm trying to find a way to find the 3D position of the ...
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1answer
157 views

Rendering Fluid Simulations?

I've read about Lagrangian and Eulerian fluid simulations and here's what I take from their methods: Lagrangian - Simulating fluid particles by calculating displacement for each particle Eulerian - ...
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1answer
114 views

3D scene construction and change of coordinates

My book says: After a scene has been constructed we transfer object descriptions to the viewing-coordinate reference frame. This conversion of object descriptions is equivalent to a sequence of ...
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1answer
76 views

Overlaying a grid on to a height map

What is the method used in overlaying a grid (agonostic of the grid type) on to a height map? It seems it's some sort of projection, but what are the technical details in how to implement it? An ...
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2answers
271 views

How can I draw this style of grid?

I'm trying to write code (in any language) to render this 3D grid, matching the look and colors as closely as possible:
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1answer
538 views

How can I use 3d animation to create a character that uses sign language?

I performed a quick search on programs that translate natural language to sign language (through a 3D animation character). Here are examples: IBM SISI ProDeaf (which is an android app) My question ...
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1answer
60 views

How to rotate a shape in another 3D software so that the rotation matches with the rotation in Blender?

I import a mesh in Blender, export it with setting axis_forward='-Z', axis_up='Y', import in NVIDIA's FleX, rotate it and store it on disk; I call this mesh ...
2
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1answer
67 views

What is the equivalent of rotation matrix in Euler angle space for Quaternions?

I have to load a mesh in Blender (which uses Z and Y as up and forward axes), modify it and export it (with setting up and ...
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1answer
3k views

How to convert Euler angles to Quaternions and get the same Euler angles back from Quaternions?

I am rotating n 3D shape using Euler angles in the order of XYZ meaning that the object is first rotated along the X axis, then Y...
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1answer
69 views

How to compute A and B in projection matrix

I'm trying to compute a projection matrix to transform from view space to NDC with a near clip plane at -1 and far plane at +1. The general form of this matrix (disregarding aspect ratio and focal ...
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1answer
73 views

How to randomly draw Quaternions within a specific range of Euler angles for rotation?

I am pretty new to Quaternions so please bear with me. I want to draw random Quaternion samples so that their Euler angle equivalent would range within [-30, +30] ...
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1answer
73 views

How are the three plane equations derived in the NVIDIA's CG Tutorial chapter 8?

I'm reading the chapter 8 of the Cg tutorial and I could not understand 8.4.1 : Because all these coordinates lie in the plane of the same triangle, it is possible to derive plane equations for x, ...
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2answers
964 views

Generate mesh from pointcloud data

Given point-cloud data : For example. position + color and normal. What will you use to generate mesh of this data and keep reasonable quality for real time cases ? Additional info to consider: ...
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1answer
77 views

how to draw mesh equal distance from irregular shape geometry bounding box

I am given an irregular geometry shape with its vertices, bounding box information. How to draw a smooth mesh equal distance from that irregular geometry shape's bounding box? Please refer to the ...
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1answer
294 views

Merge multiple Point Clouds into a single 3D object [closed]

I am testing the Intel RealSense D435 camera and have been able to create multiple Point Clouds (.ply) of a certain object. Each Point Cloud is taken in a different viewing angle of the object. Now I ...
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2answers
119 views

Relatively new to OpenGL, need guidance/tips on an assignment with interactive user input

I'm currently taking a Computer Graphics class at university, and have been given an assignment which involves loading an obj file and manipulating it with keyboard and mouse controls (eg. arrow keys ...
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1answer
64 views

How to raytrace triangular faces when camera is not at origin?

I've watched the Pixar In A Box, Maths of Rendering Tutorial on Khan Academy. I've started writing a raytracing program and have come to the point where I must solve for ...
2
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1answer
91 views

Z-buffering implementation with small triangles

For research purpose, I have to implement z-buffering algorithm to render 3D face models. But I got a problem that the triangles are too small to be rendered (i.e. there is no pixel covered completely ...
3
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1answer
78 views

Infinitely long 3D model

Let's say that I want to render something like Dimmadome's hat, a hat which has the height of infinity. A quick answer to this would be to place the top side of the hat high enough for the crown(...
2
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1answer
232 views

Light field rendering for 3d software?

Is there any 3d software that supports rendering an artificial scene to a light field image? With that I mean an image capturing light from more than one point in a scene, more lika a spherical ...
3
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0answers
33 views

Possible approach for product mockup creation including distortion created through perspective

I am not an expert in 3D nor computer graphics. Please forgive me if I use wrong wording. High level problem description: For an online shop, I would like to create mockup images of apparel (t-shirts,...
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2answers
115 views

Is there something wrong with a column camera matrix?

I am writing a simple ray tracer. I was working on my camera matrix when I encountered a problem. When I changed the look vector, so that it headed down, the image, which was supposed to go up, ...
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2answers
54 views

If a 3D scene is rendered onto a hemispherical display, will there still be warping near the edges?

When a 3D scene is rendered to a 2D display, the image is distorted near the edges of the display. If a 3D scene is rendered onto a hemispherical display, will there still be warping?
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5answers
491 views

Is there a standard specification for 3D graphic representation?

I'm reading a book on computer graphics, and at some point, it shows a 3D model, created from a .dat file. Here are a few rules for the .dat file creation: Made of a list of vertex positions / faces ...