# Questions tagged [3d]

Questions and problems dealing with three-dimensional space, including 3D meshes and other data structures, vector math, transformations, etc.

159 questions
496 views

### Normal 2D photo to VR-compatible spherical photo

How to turn a normal photo like this one : into a photo that I can use in my game development platform (Unity3D). I just wrap a 3d sphere model with the photo and then it can be all around me when I ...
64 views

### What is the name of these software on 2 screen? [closed]

Look at the photo, modelling for new products. Regards
275 views

### What if we don't mention Modelview and projection matrix?

So I've been learning opengl for some weeks now and managed to understand all the viewing pipelines. As far my understanding goes we need to bring the object to world space and then the world space to ...
1k views

### Background behind 3D model

I have object loader, which i want to have background. I tried to put jpg image like texture to my application. I tried to make that with FreeImage library, but the image didn't show. Also i tried ...
201 views

### Creating Sparks using Code

I'm new to this area and have less knowledge. I want to create some graphics like sparks and lightning by writing some code, using my own physics. I don't want to use some engine, However I can use ...
172 views

### Frustum aligned volume integration - aliasing issue - temporal reprojection

Raw volume raymarching especially aligned with frustum seem to produce a lot of aliasing/banding on edges of shadow map. Especially when fragment pos is far because step length is then getting bigger. ...
117 views

### Where should I project a polygon corner when it is behind me?

I am creating a simple 3D engine as a learning project to get the hang on spherical trigonometry. I am using the following approach. 1. A model consists of a lot of triangular faces. 2. Each triangle ...
139 views

I need to find the transformation matrix (homogeneous coordinates) that flips an object about a plane whose normal is directed towards (-2 2 0), and intersects the y-axis at y=2. I know how to do ...
82 views

### What other paradigms exist besides vector/fragment/transform graphics programming?

I am familiar with the basic concepts of writing vector and fragment shaders while using linear transformation matrices to describe orientations in 3D space. But, what other paradigms exist (...
242 views

### Transformation Matrices

Consider the following problem and its answer: Given 3 points in 3D: $A=(A_x,A_y,A_z); B=(B_x,B_y,B_z) ; C=(C_x,C_y,C_z)$ Find the transformation matrix (in homogeneous coordinates) that ...
158 views

### File format for swept profile with changing normal

I have to create a file describing a 3d surface with the following properties: a circular arc cross section is swept along a closed 2d curve spine defined with equations the normal direction of the ...
86 views

### In a polygonal mesh 3d model which consist of triangles is it possible to separate different objects?

I have a 3d city model that is a collada file which consist of many triangles. When I select the model in a 3d software all buildings are selected. But I want every building to be selectable ...
58 views

### get partial view points from 3d surface mesh

I have a 3d surface mesh. Say the camera is located in some points and I want to get the visible points from the 3d surface mesh from the camera view. I believe this kind of process would be done ...
70 views

### How can I draw a tube on basis of position and angle between two 3d points?

I'm struggling with this idea of creating two particles in 3d and draw a tube between them. I can't figure out how to properly set the angle of the tube. I've used two approaches: calculating the ...
95 views

### How to texturize a 3D model from video?

I have a base 3D mesh of an object that I want to texturize. I also have a 360 degrees video of the real-world object. What are good ways to use the video to texturize the mesh? Are there existing ...
361 views

### Perspective correct interpolation of normal values

I'm currently writing a software rasterizer and I'm at the point where I can draw arbitrary triangles with vertex colors and perspective correct texture mapping. I do point and directional lighting by ...
130 views

### Implement own Bend function

I'm trying to write a mesh deformer that bends a Cube around an axis like this: The bend degree in figure A is 90 and something like 35 in B. So if I know my desired bend degree how can I get alpha? ...
81 views

### How to convert image results into data?

I have made an 3d solar exposure analysis for a 3d city model that determines how long a surface receive direct sunlight throughout the year. Results are coloured surfaces and legend of coloures that ...
77 views

### Optimal 2D graphics resource [closed]

I am a some-what experienced programer, and I have been working on creating a 3D graphics engine utilizing the OpenGL system, primarily focused on use in games. However, I also want to do some work ...
264 views

### Symmetry plane estimation for 3D point cloud

I have a question about finding the symmetry plane that separate the left and the right halves of a point cloud. We scanned an object, say a human face, with a 3D scanner, such as Kinect, which gives ...
2k views

### Calculate vanishing point

In perspective projection, group of parallel lines have the same vanishing point. I am interesting about the reverse calculation: Getting the group of parallel lines equations that their vanishing ...
517 views

### 3D rotation matrix around vector

I am using matrix for performing 3D rotations. I know that in 3D space the matrix product order is important - changing the order of the matrices can effect the rotate result. So I am interesting ...
584 views

### How are hard and soft shadows cast?

I have been studying computer graphics, from the book Fundamentals of Computer Graphic (but the third edition), and I lastly read about texture mapping and shadow maps. Though, I didn't exactly ...
9k views

### What's the difference between orthographic and perspective projection?

I have been studying computer graphics, from the book Fundamentals of Computer Graphic (but the third edition), and I lastly read about projections. Though, I didn't exactly understand what's the ...
190 views

### Human Readable/Writable 3D Representation Formats/Languages?

My goal is to create 3D meshes without the use of a 3D editor. So I want to know what representation languages and formats there are that are designed for this or otherwise that would be good for ...
4k views

### Why do we have graphics frameworks like OpenGL and DirectX, when games could just draw pixels directly?

Games and other graphically intensive applications use frameworks like OpenGL and DirectX. Also they require features like pixel shader and DX12. But why would we need all these frameworks and GPU ...
102 views

### Generate complex (non-convex) polyhedron UV mapping

I need to find an approach to the problem of generating texture maps for non-convex polyhedrons without using a design tool like Maya. Specifically, I am mapping simulation results data onto a 3D ...
474 views

### Which 3D algorithms does Windows 10's “3D Builder” application use?

Windows 10 ships with "3D Builder", a Universal App that contains utility functions to prepare STL, OBJ, 3DS, and other files that represent geometries for 3D printing. The utility looks like this: ...
460 views

### Maximum number of vertices after clipping a triangle against an AABB

I clip a 3D triangle against a 3D Axis-Aligned Bounding Box (AABB) to obtain the largest planar polygon of the triangle contained in the AABB. My clipping algorithm is a (slightly modified) version of ...
129 views

### maximal convex patching in Computer graphics

Given a 3D object in Computer graphics, whose surface is represented as a 3D triangular mesh (mesh of 3D triangle objects), I need to find the maximum continual Convex patches on the surface of the ...
145 views

### OpenSCAD Hull/Minkowski function by hand?

I am trying to model an organic object using OpenSCAD. However this will need to be ported over to older software. This restricts the primitives I can use (only cone, cylinder, torus, sphere and cubes)...
180 views

### Free 3D Scene Simulation Framework [closed]

I want to visualize a scene with simple shapes (e.g. boxes, pyramides, etc.) and I am looking for a tool or framework in C/C++ to do this. Focus of the application is to parameterize the relative ...
357 views

### Triangulated model rasterization: light-weight Python library

I have a 3D model, which consists of ~50 thousand vertices and 100 thousand triangles. Format is: there's array of vertices' coordinates and array of triangles, which has numbers of vertices (e.g., [1,...
479 views

### Choosing & Using a Projection Matrix

I'm looking into the graphics pipeline processes and at the moment in particular, perspective projection matrices. After looking in several different sources, and across the breadth of previous ...
983 views

### What is stereo about multi-view stereo?

What 3D scene reconstruction methods does the term "multi-view stereo" encompass? Is it only used for methods that apply binocular stereo algorithms (taking 2 views as input) in a pairwise manner? Or ...
189 views

### Graphics Pipeline: Viewspace & Back face culling incorrectly

I'm attempting to model a simple graphics pipeline - using Matlab at the moment as a modelling tool to get the transformations correct. I appreciate there are software tools that would make this ...
346 views

### 3D mesh segmentation simple algorithm

I am developing the algorithm reported in this article: Least square conformal mapping. Here is presented an algorithm to flat a 3d mesh on the parametric space, but i don't understand the ...
104 views

### culling meshes across mulitple layers

I am implementing foveated rendering. My FBO is divided into 2 layers which are concentric. The first layer covers 1/3 of the Framebuffer whereas the second one covers the rest of the screen. Now I ...
159 views

### Why is rotating this prism in iOS Metal not rendering correctly?

I've set up a test project for learning Metal on iOS to do some rendering, but I'm a bit stumped on how to get a prism rotating correctly about its y axis. Here is the prism rendered without depth ...
227 views

### Spine. What is the name of the process?

https://www.youtube.com/watch?v=twUz99ek5do&list=WL&index=5 There is a process from 1:51, where the guy start making polygons around the bodyparts. I think this is this part is where (with ...
148 views

### Sphere intersection occlusion (for hybrid raytracing)

Thinking about hybrid raytracing, hence the following question: Suppose I have two solid spheres $s_1$ and $s_2$. We know their centres and radii, and we know that they have some overlapping volume ...
140 views

### Project quad onto ellipse in 3D

I have three points P0, P1, P2, which are located on an arbitrarily oriented ellipse in 3D space. I have a square texture map with a circle on it. I would like to render a textured quad (with the ...
178 views

### How to get the transform amount from a screen vector and a direction vector?

I am working on the move tool in a 3D modeling software. I need to know how much to move when the user drags an axis of the gizmo (for example along the x axis). I have the 2D vector describing how ...
722 views

### Is my perspective math correct?

I've got a homework in which I have to calculate and plot some points using a pespective transformation, but I'm not sure my results are correct, since the 3d plot using Camera coordinates looks very ...
256 views

### NURBS topology classification

In what sense is it true that a NURBS surface can only have the topology of a plane, cylinder or torus? For example I can do a NURBS sphere. Is the sphere homeomorphic to one of the above surfaces?
164 views

### After a deformation operation on polygons, how can I check for and fix inverted polys?

I'm doing a quick and dirty automated deformation routine on a polygon body. If it was a tree, and my axis was in the center of the tree, I would like to bend the body by bending the axis. I would ...
257 views

### Why smoothed meshes in 3D studio end up with the same number of vertices/triangles? How then can they be smoothed with the same geometry?

I am trying to understand why meshes that are smoothed in 3D studio (Modifiers/Smoother) end up having the same amount of vertices/faces before or after that process, as well as the exact same ...
225 views

### Earth curvature and horizon in modeling large scenes

If I want to model a large environment, how can I solve the problem of earth curvature and horizon? I use an environment map for the sky, but for the ground what can I do? Do I have to model the ...