Questions tagged [3d]
Questions and problems dealing with three-dimensional space, including 3D meshes and other data structures, vector math, transformations, etc.
211
questions
1
vote
0answers
29 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 ...
1
vote
0answers
45 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 ...
0
votes
0answers
22 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
50 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 ...
0
votes
0answers
51 views
Consistent Video Depth Estimation from Monocular Lens to approximate LiDAR?
If the iPhone had LiDAR sensors, it would be possible to generate a 3D point cloud that you could theoretically use to furnish a 3D AR reconstruction of your surroundings. E.g. you could create an AR ...
0
votes
1answer
42 views
Is it viable to create computer graphics via terrain scanning?
Couldn't find any resources on this, so I'll ask here.
For example, I want to create a game model of a mountain peak.
I took lots and lots of drone footage, almost from every side, photography ...
-1
votes
1answer
93 views
When do people need to work directly with a graphical API (eg: Direct3D) instead of using already made software?
I had this doubt in my head for several months and have been unable to find an answer anywhere on internet.
I know what OpenGL, DirectX, Vulkan, Metal, etc... are, I already know what they are used ...
0
votes
1answer
45 views
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 ...
0
votes
0answers
34 views
When do I need to use a triangulate function?
I have some misunderstanding about the modeling pipeline. In my mind pipeline are:
Concept
Sculpt
Retopo
Baking
Rigging
Setting
Animation
Game engine or cartoon/movie
...
I read many articles about ...
0
votes
2answers
78 views
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) ...
0
votes
0answers
15 views
How to create a 3D volume model from vtkImageData?
How can I create and save a 3D volume model from a volume image vtkImageData?
Some people recommend vtkImageDataGeometryFilter, so I tried the following:
...
1
vote
1answer
65 views
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 ...
0
votes
1answer
61 views
glBindImageTexture returning INVALID_VALUE
I am currently having an issue with OpenGL as I am trying to load some vector information into a 3D texture. Currently, I am developing in OpenGL 4.6 which should support Image bindings.
this my ...
0
votes
0answers
50 views
Mathematics in Computer Graphics
Can you please recommend some topic for research work related to mathematics in CG?
(Maybe something like "Affine transformations in CG")
0
votes
1answer
44 views
Keep constant number of visible circles in 3D animation
I have created a 3D animation with a perspective projection of white circles moving randomly in a fake 3D space projected on a 2D computer screen (GIF 1).
Since I need to keep the same number of ...
0
votes
1answer
25 views
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 ...
0
votes
1answer
55 views
constant pixel width for any scale
I have a standard 3d camera/projection/model setup that renders rectangles with a WebGL shader.
Users can zoom out and fly anywhere.
I want to make sure that regardless of the scale, width of the ...
0
votes
1answer
68 views
Graphics engines during the sixth console generation
From my understanding game developers used mostly proprietary, in-house graphics engines during the sixth console generation (Xbox, PS2, GC, DC) on a game to game basis. Why didn't standard engines ...
0
votes
0answers
53 views
What is it that really prevents photo-realistic, real-time, digital 3D simulations?
Ever since I was a small child, seeing the amazing 3D visuals that developed in the 1980s and 1990s, I was certain that photo-realism was "just around the corner". In the year 2020, I certainly ...
1
vote
1answer
73 views
Defining “inside” and “outside” of a 3D space
I am not sure if this is the correct SE to ask this question. However, lets say I have been given 3D models of several enclosed spaces.
I want to populate spaces with, lets say, planes flying through ...
0
votes
0answers
15 views
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 ...
1
vote
2answers
45 views
Y axis inversion in 3D rasterization
What is the correct way to invert the y axis during the 3D projection?
I see a lot a people doing:
...
0
votes
0answers
30 views
After making any 3D model using Opengl how to export it's data in .dae file?
I'm trying to make simple 3d modeling program in c++ with Opengl. So I don't know how to transfer/convert/export or save data of 3D model in .dae file.
NOTE:- 3d model is made using Opengl ...
1
vote
0answers
90 views
Intrinsic Matrix vs Perspective projection matrix
I was going through the camera matrix explained in the wikipedia article and understand how the matrix K \begin{bmatrix}f_x&s&x_0\\0&f_y&y_0\\0&0&1\end{bmatrix} is built. The ...
0
votes
0answers
46 views
Estimate 3D cube pose after camera rotation
I have some photos of 3D cube. I also know the 3D pose of the cube in each photo (yaw, pitch, roll).
I want to estimate the new pose (yaw, pitch, roll) of the cube after performing 2D rotation to the ...
0
votes
1answer
46 views
Understanding the near clipping plane
I don't understand something about the near clipping plane. It's there to avoid the division by $0$ but when we compute the pixel coordinates, we just need to multiply by the clipping plane to clip ...
1
vote
0answers
84 views
BSP tree rendering
As a little project, I'd like to implement a BSP merging algorithm for Boolean operations on solids. But to even tell whether it works, I need some way to render the BSP tree. In other words, I have a ...
0
votes
2answers
266 views
What are “Triangles” in 3d modeling?
In 3d modeling, there is some "triangle count" which determines complexity. I am not sure but I think cubes have 12 triangles or somethong. But I see NONE. They have squares, no triangles! Can someone ...
2
votes
1answer
87 views
How can I raycast with chunks?
I am attempting to implement chunks/octrees to speed up my render times. However, sometimes the walls show horizontal or vertical lines (rays hitting the inside of voxels?) or some blocks disappear ...
0
votes
1answer
58 views
Why is the z direction away from the screen/viewer?
I wonder what is the reason that when z increase, the objects appear far away and when z is negative, the object is behind the camera?
4
votes
3answers
91 views
Visualize the interpolated unit quaternion on the surface of the unit sphere
My major is mechanical, please forgive me for asking questions that may seem trivial to you.
First, I'm reading the following paper:
Dam, Erik B., Martin Koch, and Martin Lillholm. Quaternions, ...
0
votes
1answer
78 views
Compute Speed of Spheres in 3D animation
I have created two animations:
One where a "camera" moves towards the spheres creating an optic flow (1st GIF).The code can be found here.
One where spheres move randomly in a 3D coordinates space (...
2
votes
1answer
168 views
Rendering equation for spherical lights
I am currently implementing spherical lights in my DirectX game engine. I decided to build the shading formula from the classical rendering equation. Here is what I get:
The simplifications show that ...
0
votes
0answers
25 views
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 ...
1
vote
1answer
37 views
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 ...
0
votes
1answer
35 views
Is it possible to set visible and color for all 12 edges(spines) of the figure (cube) in matplotlib?
In 2d, matplotlib plots all 4 edges(spines) of a figure.
In 3d, matplotlib plots 9 out of 12 edges of a cube.
Is it possible to set visible and color for all 12 edges(spines) of a cube in 3d?
I ...
0
votes
1answer
45 views
Why does my code generate a figure whose kurtosis looks a little higher than the one I am trying to reproduce?
this figure (fig_1) is an univariate normal distribution in 3D, the corresponding equation is in the top left hand corner
it seems that x varies from -5 to 5; sigma varies from 0 to 4.
This Python ...
1
vote
1answer
43 views
Why does my code to plot a cone actually generate a roof?
per this post, this formula
$Z = 1 - \sqrt{X^{2} + Y^{2}}$
generates a cone where the point is at (0, 0, 1) and it spreads out below that. It meets the x-y plane at the unit circle
I am trying to ...
1
vote
1answer
83 views
Could some give an explanation or hint about this kind of equation? $\left(- \sqrt{X^{2} + Y^{2}} + 1\right) \cos{\left (2 \pi X + \phi \right )}$
This is a screen shot from an animation generated by a matplotlib example
the key part in the code is
...
4
votes
2answers
81 views
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 ...
2
votes
1answer
1k views
What's the difference between Clipping and Culling?
In a tutorial about OpenGL both words are mentioned, unfortunately without a good explanation.
To find out, I have read this article three times, but I fear I'm a too common man... my understanding is ...
2
votes
1answer
139 views
Calculating the angle between two polygons
For my application, I want to render models as polygonal surfaces in 3D space and have edges that are bent "outwards" to have a solid line and those who are bent "inwards" to have a dotted line. So if ...
0
votes
1answer
71 views
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)
...
1
vote
0answers
16 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 ...
1
vote
0answers
142 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 ...
0
votes
2answers
483 views
How can i wrap the earth image around a 3D Sphere 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 ...
0
votes
1answer
492 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 ...
1
vote
0answers
94 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 ...
3
votes
2answers
936 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 ...
0
votes
0answers
123 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 ...
