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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Vertices, Vertex Normals and Face Normals

Using Open 3D Model Viewer, I have converted an OBJ file to an STL file. In the source file, the Vertex Normals are specified and in the destination, the face normal of the triangles are present which ...
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71 views

Rounding a 3D corner with Subdivisions

Following the instructions from this post on Stack Overflow, I have been able to find points A, B, and C from points V1, V2, and V3 and a radius value (code below). I would like to be able to find a ...
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Retaining hierarchy of assembly when converting STEP to GLTF

I want to convert STEP files to gLTF. I know that gLTF suuports hierarchy of assemblies and parts. Source: https://cadexchanger.com/blog/283-how-to-load-3d-cad-data-into-three-js-part-2 However, it is ...
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Blend Shape, Pose Blend Shape, and Shape Blend Shape

Since there is a lot of cross-section between computer vision and computer graphics for 3D pose and shape estimation of non-rigid objects, I would like to know what "blend shape", "pose ...
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1answer
24 views

Real 3D interior room from 360 images

If I have 360 images of an interior room from all different angles, would it be possible with current 3D software technology to create a real 3D representation of that room, where the camera could ...
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1answer
58 views

Detect collision for non axis-aligned bounding boxes

in my application, I needed to detect collision between 2 3D objects. To make it simple I can represent a object as a bounding box. So actually the task reduced to detect collision between 2 boxes in ...
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2answers
51 views

How to decide which way to triangulate a quad?

Apologies if this is a dumb question... but given four arbitrary (non-coplanar) points in 3D space, there are obviously two different ways to triangulate the quad that they form. One triangulation may ...
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3answers
65 views

How to Sample 3D Points Outside and Inside the Mesh Surface

I have a mesh of an object enclosed in unit volume cube and I would like to sample points inside and outside the mesh surface. What are the different ways of doing it? Is there any sample code ...
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Is there a term for this sort of graphics?

I'd like to try to write some C code to create similar animated graphics to these, which are from a very old Commodore 64 game called "The Sentinel". I've been researching but I can't seem ...
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2answers
54 views

Shear(?) matrix projection along Z (depth) axis

I'm creating a primarily 2d game (platformer perspective) with 2d background parallax layers. The parallax effect falls out of the fact that I'm positioning a bunch of layers in 3d and using a ...
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Clipping 3D Perspective matrix

I am trying to implement clipping in my simple renderer, but i have a trouble with setting the boundaries. I used the same projection matrix that is in OpenGL. The problem is, the vertices that are ...
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What's a good research topic in Computer Graphics?

I am currently trying to find topics for my master's thesis. I would really like to do something in the field of computer graphics, but I've been having trouble finding what are some current problems ...
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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 ...
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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 ...
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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 ...
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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 ...
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56 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 ...
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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 ...
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102 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 ...
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1answer
75 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 ...
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36 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 ...
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2answers
89 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) ...
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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: ...
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1answer
90 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 ...
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1answer
86 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 ...
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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")
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1answer
53 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 ...
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1answer
41 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 ...
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1answer
67 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 ...
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1answer
71 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 ...
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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 ...
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1answer
88 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 ...
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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 ...
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1answer
50 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: ...
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31 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 ...
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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 ...
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50 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 ...
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1answer
58 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 ...
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91 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 ...
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2answers
303 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 ...
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1answer
103 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 ...
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1answer
66 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?
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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, ...
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1answer
80 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 (...
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1answer
178 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 ...
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26 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 ...
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1answer
39 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 ...
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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 ...
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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 ...
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1answer
45 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 ...

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