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# 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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45 views

### Generate camera trajectory with cameras' lookat following shape

I am trying with no avail to create a camera path that follows a lemniscate shape as shown in the figure. I do it in 3D but just set the vertical dimension (y) to a fixed number so really is 2D. the ...
22 views

### How to I convert FLAME model parameters (for the face) into 51 arkit blend shapes [closed]

['dynamic_lmk_bary_coords', 'hands_coeffsr', 'allow_pickle', 'lmk_faces_idx', 'f', 'J_regressor', 'hands_componentsr', 'kintree_table', 'hands_componentsl', 'joint2num', 'hands_meanl', '...
14 views

### Querying a point to find the tetrahedron it lies inside in 3D

I have a set of non-intersecting packed tetrahedrons in 3D space. What is the most optimized way to find the tetrahedron inside which a query point lies? Edit: I tried some data structures and ...
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34 views

### Measuring sphere angles to triangle

I'm looking at using multiple importance sampling for path tracing, and doing some lighting calculations relating to spherical lights. I'm trying to decide, given a triangle and a point on that ...
• 103
1 vote
42 views

### Automating equirectangular horizon detection in 360 images

I would like to programatically identify pitch and roll numbers that will level the horizon on each frame in a series of equirectangular 360 panorama images. Here's why. I recently ended up with a ...
• 111
1 vote
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### How to create a more photorealistic ocean?

Photorealism has many elements. Take, for instance, the figure 1 below, a shot from Dune Part One movie. Figure 1 The process of production of a image such as this one, is laborious and involve more ...
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142 views

### Preferred GPU API to use for Steam Deck, Windows, Linux and MacOS support

Good people of the graphics SO community, I am new to Graphics programming or GPU programming in general but I have been a game dev enthusiast for over 4-5 years. I started learning about Graphics ...
• 101
71 views

### Curvilinear triangle grid

I'm trying to figure out how the Adobe Illustrator's Inflate effect works. Basically, it converts a vector graphics object to a 3D mesh and displaces its vertices proportionally to how far they are ...
77 views

### How apply 3d transformations on 3d Mesh vertcies

I have This 3D mesh class , I use helixToolKit SharpDX to display the mesh and transformations , but i want to apply these transformations to the vertcies dirctly so the mesh can be exported with ...
19 views

### How to extract points corresponding to faces from cube map projection (CMP) of panorama from point cloud data

I am working with the standford2d3d dataset http://buildingparser.stanford.edu/dataset.html which contains panoramas of various scenes and a .mat file of the point cloud information of all the scenes. ...
47 views

### Problems with distributed ray tracing and particle system

based on the ray tracing stunning effect, I'm considering a resilient distributed ray tracing implementation, I've just finished a basic computer graphics course, and I'm currently working on directX ...
166 views

### Understanding spherical harmonics code

I am trying to understand the function computeColorFromSH, which is a part of the differentiable gaussian rasterizer used by the paper 3D Gaussian Splatting for Real-Time Radiance Field Rendering. I ...
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### how can I estimate the depth of an object with a bound box from just a few images where i moved it?(knowing how much i moved)

how can I estimate the depth of an object with a bound box from just a few images where i moved it?(knowing how much i moved) For testing purposes I have a cube and a camera perpendicular to it and I ...
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124 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 ...
21 views

### How to retrieve a mask for a partially filled 3D Truncated SDF based on its ground truth?

I am trying to create a mask which is required for a 3D inpainting task. My data contains 3D truncated SDF grid of size 64*64*64 with a truncated value of ...
64 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 ...
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47 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 ...
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1 vote
53 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 ...
• 111
32 views

### Object appears in unintended parts of the screen when using manual WorldToScreenPoint

Hy guys I'm new to 3d graphics and i lack some Linear algebra knowledge. I tried to recreate Unity's worldToScreenPoint method with kotlin on android. I copied some code from their forum and wrote ...
98 views

### HTML Canvas not drawing

I'm working on a 3D Renderer with the canvas element and JS but currently the cube I made is not rendering. I currently have it set to just render a wireframe of the cube and am hoping to render the ...
73 views

### Rotating a set of cameras to look at a rotated object

I'm trying to use Instant NGP on a synthetic image dataset. I have image sequences of a moving object with the following information: I have the object's xyz and the camera's xyz positions in a void. ...
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38 views

### 3D engine projection distortions

I'm trying to write my own 3D engine using Python and Pygame. I have successfully implemented rotation and projection matrices to display 3D models. However I am so far unable to implement translation ...
72 views

### Patchy patterned artefacting in depth buffer

I am writing a polygon rasterization renderer. Some meshes render flawlessly, but some produce strange artefacts in the depth buffer. These artefacts do not just appear when I save the depth buffer ...
92 views

### How to setup a 3D camera

I'm trying to figure out how to setup a 3D camera in WebGL. This is my first swing at 3D so a lot of the matrix stuff is new to me. Code The code can be reviewed in this CodePen: https://codepen.io/...
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1 vote
230 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. ...
• 135
1 vote
67 views

### Unknown array of floating point numbers. View matrix?

I want to control the camera in an old game using head tracking (TrackIR, opentrack, etc.), such control was not provided by the game engine. I'm trying to find the camera coordinates and rotation ...
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241 views

### Creating a UV Map for a 3D Cone

I have the following problem I am currently facing. I am creating the vertices for a cone based on the number of segments and the radius of the base and top. This is done as follows: ...
• 167
40 views

### Optimized 3D rendering using dots and/or line segments of different sizes in Scratch

I'm developing a 3D rendering engine in Scratch, which is a block-based visual programming language. It does not have any support for bitmap rendering, but there is a "pen" plugin that lets ...
1 vote
47 views

### How to display real time 3-D orthogonal vector rotations?

I'm an embedded developer here with very little experience in computer graphics. I'm currently working on a GUI that can display a calculated inertial solution at run time. I have hardware that can ...
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 ...
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287 views

### Why are the transformations of an object calculated on CPU?

If I understood correctly this is the process of rendering an object: Array of 4d vector defining points 3d points(with the fourth component 1) representing object's vertices in object/local space: <...
2k views

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### Glowing objects in a raytracer? How it works?

My raytracer has a point light source, it works as it should, illuminates the scene, but there is a problem, it is not visible, I would like to add glowing objects to the raytracer, for example a ...
2k views

### How to convert from world coordinates to camera coordinates

In the world coordinate system, there are objects with rotation values rx1,ry1,rz1 and position values px1,py1,pz1. Similarly, ...
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1 vote
36 views

### help with libgil tutorial (python binding)

could you please give me some guidance on following this libgil tutorial? https://libigl.github.io/libigl-python-bindings/tut-chapter0/ The problem: When I do the first example (two yellow triangles), ...
40 views

### Approximate compass bearing of a normal

Let's say I have a 3D model that represents a small real-world space; it could be bounded by a 10" by 10" by 10" box. I know the real-world compass bearing for an observer in the center ...
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93 views

### Trouble getting a raytracer camera representation for different aspect ratios

I am trying to make my camera representation work for images whose aspect ratio isn't 1 (640x480, 1920x1080...), but I am having some trouble getting it to work. The camera model is pretty simple, as ...
• 101
66 views

### Camera Perspective of 2D X/Y Plane

I'll start with the coordinate system I'm trying to use: If I were standing on the ground, facing north, the x axis is a line moving from the west to the east (positive X is east). Positive y is ...
• 101
71 views

### Starting from a basic glTF (such as a static sphere or plane) exported from Blender how can I add an animation manipulating its JSON?

I'm working on a glTF, precisely I'm trying to animate a "static" mesh exported from Blender directly acting on its JSON. In doing so, I'm following the logic used in this tutorial , where a ...
83 views

### Identifying an openGL 3d model

I currently have an application that uses openGL in order to render a 3d model of a car. I would like to change the car models but I have no clue what format my application uses. The current format of ...
668 views

### Is a line drawn using vectors, triangles or polygons within OpenGL? [closed]

Trying to understand how OpenGL generates what is seen as images & graphics and these questions come up. Are 3D lines (which should be drawn using vectors) drawn using triangles or polygons? Or ...
152 views

### Point a normal vector towards a point in 3D-Space

Given a normal vector in 3D-Space, how can I rotate the vector, such it points to a point in 3D-Space. I tried couple of ways doing this, which ended up looking completely wrong.
1 vote
40 views

### What is the proper term for 3D models which are similar but not necessarily the same size, orientation, face-count/tesselation, etc?

Sup[pose I have a model of a unit cube (12 faces) aligned to the three axes, and another model of a cube divided into thousands of faces and hard-coded in a random orientation. They are both cubes, ...
• 341
190 views

### Finding Camera projection matrix from known input and output

Lets say I have a rectangle with known coordinates in 3D scene, and I'm projecting it using pin point camera to the plane (screen). You can imagine it deforms on the screen per camera transformation ...
212 views

### View rotation matrix

Im unsure about how I could describe what im trying to achieve in few words or a title so ill go on to describe it. So I have voxel, in 3D space, represented solely by its center. The voxel though, is ...
292 views

### Convert one triangle to another in matrix4x4?

The context openGL instances learning. I want to transform a reference triangle to another one. So final goal is to have one triangle and the instance being a transformation of that initial triangle. ...
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1 vote
361 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 ...
1 vote
72 views

### What fields should a camera class have?

For a good and scalable project structure, what fields would you add to a camera class, apart from its position and orientation? Should I add the near and far planes? Or should that be global, what ...
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