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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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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2 votes
1 answer
60 views

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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-1 votes
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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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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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2 votes
1 answer
120 views

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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2 votes
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69 views

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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How to convert a fisheye image to equirectangular image?

Hi i am rather new to computergraphics but i am trying to map fisheye image to an equirectangular image. The method i am following to do this is getting a lat/lng from equirectangular image and use ...
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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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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 Ed Catmull'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 (in ...
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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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3 votes
1 answer
79 views

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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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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2 votes
2 answers
163 views

$(x, y, 1)$ 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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178 views

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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How to compute centroidal power diagram for 3D objects?

In this paper, Packing Irregular Objects in 3D Space via Hybrid Optimization, the authors used the centroidal power diagram method to divide a container into $m$ subregions for $m$ irregular 3D ...
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2 votes
5 answers
1k views

Existence of vanishing point

Consider the following example of perspective projection: I have one railway track with two parallel lines meeting at the point $X$ at infinity which is the theoretical approach. This X is called the ...
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1 vote
0 answers
55 views

3D shearing w. r. t $x$-axis [closed]

Shearing in $X$ axis is achieved by using the following shearing equations- $X_{new} = X_{old}, Y_{new} = Y_{old} + Sh_y × X_{old}, Z_{new} = Z_{old} + Sh_z × X_{old}.$ My question is during $Y_{new}...
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4 votes
1 answer
262 views

Difference between 2D and 3D pipeline

2D transformation and viewing: The camera projects the 2D world co-ordinate $(x_w, y_w)$ on its projection plane which co-ordinates $(x_v, y_v)$. 3D transformation and viewing: The camera projects the ...
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1 vote
2 answers
152 views

Difference between perspective and parallel projection [closed]

We know that in orthographic Projection Projectors (projection vectors) are perpendicular to the projection plane. And in Perspective Projection Object positions are transformed to the view plane ...
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2 votes
1 answer
157 views

$P^2$ vs projection plane

I want to explain what I understood of definition of the two things. Projection plane: The general processing steps for modeling and converting a world coordinate description of a scene to device ...
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1 answer
200 views

Calculating UV coordinates for sampling texture atlas

I have an 8192x8192 texture atlas that contains 1024x1024 shadow maps aligned side by side. I'm trying to calculate the uv coordinates so that I can sample each shadow map appropriately based on the '...
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278 views

OpenGL transparency - object behind is not rendered

I'm trying to implement voxel world using OpenGL (Core 3.3). I've come across a problem with transparency. It looks like sometimes GPU decides to not render stuff that would be important. Can you help ...
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Motivation behind tesselation

This question is NOT about the hardware difficulties and shortcomings of tesselation shaders I am trying to understand the motivation behind tesselation shaders. Why/when/where tesselation is a good ...
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Is it possible that a superior, undiscovered 3D rendering method exists?

As far as I know, the only options we have for true 3D rendering are polygonal rendering, ray-marching and raytracing/casting. Why is that? Surely there must be other ways? Is there some paper ...
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Methods to interpolate between 2 topologically identical 3D meshes

I have 2 3D surface meshes. These meshes have vertex-correspondence and have the same topology (same edges and triangles connecting the vertices). However, the vertex positions (3d coordinates) are ...
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1 vote
0 answers
42 views

Proprietary 3D Format Reverse Engineering: What Could These Numbers And Matrices Represent?

I'm trying to reverse engineer a model format from an older Russian game (Pathologic) with limited success. It is a proprietary model format not recognized by any converters/editing tools (believe me, ...
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2 answers
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Why do OBJ files contain so many duplicate vertices if they use indices to define faces?

I have been experimenting with loading in OBJ files into memory using tinyobj. I have also been learning and analysing the OBJ file format specification. I have some code which loads the BMW car model ...
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1 answer
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How to ensure that a randomly-generated velocity vector moves the camera forward within a valid arc?

I spawn a camera in a scene using random coordinates for x and y and setting z=0 and orient ...
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How does 3D graphic software adjust for distortion inherent in perspective projection?

As this question and its answers point out, projecting a sphere on a flat picture plane, with perspective projection, may result in a ellipse, not a circle, and my understanding is that the only way a ...
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39 views

Calculating the intersection of two volumes

What is an efficient way to calculate the volume of intersection of two arbitrary volumes described as closed surfaces? That is, with two meshes, A and B, how do I calculate the intersection of A and ...
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1 answer
89 views

How compute new camera parameters given a velocity vector?

My goal is to update camera parameters given a velocity vector so that the camera points in the direction of the velocity vector. How should one compute the update matrix for the camera parameters?
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Convert point clouds into voxels

I have points that are obtained by sampling a mesh(which is not watertight). Now, I would like to convert that mesh into voxel? Does anyone have any suggestions for solving this problem?
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2 votes
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Why do materials have both an ambient color and a diffuse color?

One of the first things I learned about computer graphics lighting (and light in general) is that when a ray of light hits a surface, the surface absorbs certain colors and the light retains the rest. ...
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31 views

Is there a Performance Penalty for LOD objects with different topology?

I have a fairly complex-shaped object I've modeled, and in creating the LOD meshes, I've merged some verts, deleted some and even added some after in cases where this manipulation produced an n-gon. ...
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1 vote
1 answer
259 views

How do I extrude a 2D Bezier curve representation into a 3D solid using Python?

Where P is the control point, w is weight. I plan to extrude this 2d representation into 3d. I have a discrete 2D representation (array which has [n_points, 2, 1] for each sample) of an airfoil that ...
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3 votes
3 answers
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How can I get a signed distance (SDF) from a mesh?

I am trying to use constructive solid geometry (CSG) and boolean operators to combine various shapes and get the outer (possibly concave) hull. This seems to work okay when using primitive shapes like ...
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1 vote
0 answers
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How to extrude a face from a selected mesh in Babylon,js using the ExtrudeShape method?

I'm trying to extrude a face from a selected mesh in Babylon.js using the ExtrudeShape but can't figure out why I got flipped faces. The bottom extrusions always comes flipped for a reason I ignore. ...
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0 answers
48 views

UV coordinates calculation broken

I've tried using the classic formula of calculating barycentric coordinates. When the plane on which you are projecting the texture is collinear to any of the base vectors it crashes with a division ...
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1 vote
2 answers
543 views

How does OBJ format determine vertex normals?

I have a very simple obj file: ...
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Under what conditions does a mesh operation cause the mesh become non-manifold and how to avoid it?

I'm implementing some mesh operations (e.g. edge collapse, edge split, edge flip etc) and need to ensure applying such operations does not cause the mesh to become non-manifold. However, I'm not sure ...
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1 answer
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Plotting points along a 3D line segment

I'm trying to plot some points along a 3D line segment and could really use some help. In 2D, I've found success getting the angle of the line, the sine & cosine of the angle, and then adding the ...
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0 votes
1 answer
451 views

What software was used to make KDA - Villain?

I want to try making small clips with realistic environment with the lighting in the KDA music video... Any ideas what kind of program to use?
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1 answer
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Calculating Material/Texture Placement from Bitmap to 3D Model

everyone! I am currently developing a program that converts a 3D model to 2D isometric pixel art. Part of my program extracts the texture from an FBX file (as FBX files can have textures built in), ...
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2 votes
2 answers
150 views

Why do some videos look smoother and others don't on the same monitor

I have a Dell monitor with 60 Hz refresh rate and therefore games playing on it are not very smooth as compared to 120 hz. But when I open videos on YouTube of the same game on the same monitor, some ...
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3 votes
2 answers
163 views

Mathematical Foundations of Radiative Transfer

I'm new to learning about ray tracing, but have been fairly confused by the mathematical foundations of it all. Specifically of radiometry/radiative transfer. I've internet searched a lot and skimmed ...
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0 answers
45 views

3D Bouncing Cube

I'm trying to write a little program with a bouncing cube but I can't find the right x, y, z and angle for it. I have these lines: ...
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2 votes
0 answers
70 views

Atmospheric scattering band/seperation artifact

I am currently experimenting with some atmospheric scattering in glsl in my OpenGL engine. I am experiencing a strange phenomena where a strange band / separation artifact appears along the middle of ...
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