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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How to slim nose using face mesh [closed]
I want to implement the nose slimming beauty effect programmatically. I was seeing the YouCam app, and they do it in a perfect way. How can we achieve that in code? Are there any techniques or free ...
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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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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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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 ...
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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 ...
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13
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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 ...
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25
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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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30
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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 ...
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60
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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 ...
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55
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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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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.
...
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Cropping a .usdz file
I have a program that is creating usdz 3D models from real world objects. I would like to be able to crop those objects in 3D space to remove extraneous nearby objects or walls. Is there a good ...
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64
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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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84
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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:
...
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31
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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 ...
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44
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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 ...
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53
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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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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:
<...
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462
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Conversion from W/cm2 ( or W/m2) to W/sr
I was reading a thread where you have comprehensively answered about radiometric units (Deriving radiance from irradiance and intensity).
My question is whether we can convert from W/cm2 ( or W/m2) to ...
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118
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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 ...
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993
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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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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), ...
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40
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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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Why is my cube triangle glitching?
This is driving me absolutely insane, I am battered and defeated
I'm following a tutorial on projection matrices and everything seems good......... except this ONE polygon. I have checked all 3 ...
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76
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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
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52
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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 ...
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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 ...
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72
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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 ...
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298
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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 ...
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125
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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.
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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, ...
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111
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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 ...
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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 ...
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190
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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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242
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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 ...
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71
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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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How to derive Field of View (FOV) angles from a 2D projection
I'm looking for some guidance.
I'm not sure if this is possible, and I'm not sure where to start.
I need to measure the FOV angles of a first-person, 3D game using only gameplay screenshots.
I'm bound ...
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What stops the auto-generated 3D worlds of Google Earth Pro from being MUCH more detailed and accurate?
I'll admit it blew my mind when I first realized that you could actually enter a "first-person mode" in Google Earth Pro, and not just view the 3D maps from a floating camera in the air. But ...
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136
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How to translate screen coordinates of a 3d point as the viewport size changes assuming camera state remains constant?
Okay, so let's say I have a point in 3d. And I have a camera state. That is, I know the camera position, the camera target and the camera up vector.
I am using the perspective projection to get the ...
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143
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Has the Stanford Bunny ever been re-imaged?
The photographic version shows much more detailed fur than the popular test image.
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148
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physics/math of lighting gradient of a 3D object
Consider a monochrome ball. The colours of the pixels is a function of the point height, the light intensity, the light angle, and the surface material (reflection).
What is the simplest formula ...
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Plane detector: information provided is convex hull and pose (transl + rot). Are the "extents" the scaling?
While calibrating a system that includes the automatic detection of planes from the SLAM output, the information about planes provided is:
1 - (x,y) pairs representing the plane's convex hull
2- the &...
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151
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Why we calculate z buffer value from plane equation $AX+BY+CZ+D=0$?
Suppose in perspective projection $(x, y, z)$ coordinate projects to point $(x_p, y_p, z_{vp})$ in projection plane $AX+BY+CZ+D=0$ where projection plane kept at $z_{vp}$ position. And the plane $AX+...
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Why does today's "Metaverse" look equally or even worse than the 1990s 3D chat worlds? [closed]
In late 1990s and early 2000, I tried out "Active Worlds" and more. They let me register an account and then walk around in a vast 3D world and chat with people/avatars. It was surreal and ...
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Historically Significant 3D Bicubic Patch Data?
The little milk pitcher / jug in Martin Newell's 1975 PhD thesis “The Utilization of Procedure Models in Digital Image Synthesis”, does anybody have the bicubic patch data for it? The teapot's data (...
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69
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Using Perspective Rendering To Render A 3D Point
I am wondering how I can use perspective rendering to render a point onto a screen. An image showing perspective rendering:
Say I have a 3d point (with x, y, and z coordinates), a point for the ...
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Which provides better intuition: THREE.Geometry or THREE.BufferGeometry?
THREE.js recently dropped support for THREE.Geometry in favor of exclusively THREE.BufferGeometry. I'm trying to decide which paradigm to teach in my computer graphics course to best provide students ...
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312
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3D homogenous coordinates versus 4D homogenous coordinates
We know that any 2D point $(x, y) $which represents as 3D homogeneous coordinates is of the form $(x, y, 1)$ which is the points of projective plane $P^2.$
If I use the same concepts for 3D points $(...
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$(x, y, 1)$ is 2D homogenous coordinates or 3D homogenous coordinates?
We know that $(x, y, 1)$ are the homogenous coordinates of a 2D point $(x, y)$. $(x, y, 1)$ has 2 degrees of freedom. That's why we should call it 2D homogenous coordinates. But many websites say it's ...
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263
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Perspective transformation is perspective projection? [duplicate]
I know that (
Reference )in transformation source and destination has same coordinates dimensions. But in projection destination coordinate system has fewer dimensions than the source coordinate ...
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