Questions tagged [3d]
Questions and problems dealing with three-dimensional space, including 3D meshes and other data structures, vector math, transformations, etc.
202
questions
1
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1answer
49 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
2answers
33 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
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0answers
41 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
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1answer
38 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
24 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
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0answers
28 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
67 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
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0answers
49 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
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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
42 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
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0answers
27 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
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0answers
57 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
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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
42 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
75 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
195 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
73 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
53 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?
3
votes
2answers
63 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
73 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
155 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
20 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
0answers
22 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
42 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
72 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
606 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
107 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
57 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
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0answers
14 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
112 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
441 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
310 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 ...
0
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0answers
20 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 ...
1
vote
0answers
88 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
600 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
98 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 ...
3
votes
1answer
416 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 ...
0
votes
0answers
67 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)...
3
votes
2answers
374 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 ...
0
votes
1answer
173 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 ...
1
vote
1answer
151 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, ...
0
votes
2answers
184 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 ...
0
votes
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 ...
2
votes
0answers
56 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 ...
2
votes
1answer
80 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 ...
0
votes
1answer
142 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 ...
