Questions tagged [3d]
Questions and problems dealing with three-dimensional space, including 3D meshes and other data structures, vector math, transformations, etc.
22
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What is the use of homogenous divide?
This question perhaps has been asked and answered a thousand times, and yet I haven't found any that satisfy me. The reasons are often these:
1/ You need a 4 dimensional vector to work with 4x4 ...
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1
answer
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How to derive a perspective projection matrix from its components?
This has been haunting me for several days now. I want to find the component that makes up of this 4x4 perspective projection matrix, with $l$(left), $r$(right), $b$(bottom), $t$(top), $n$(near), $f$(...
- 207
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Building view transform matrices
For a 3D scene in the world coordinates, its View Reference Point $\mathrm{VRP}$ is at $(5,-2,1)$, and a viewer is looking towards point $A=(1,1,1)$. Construct a transform matrix which will map world ...
- 317
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5
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Why are quads used in filmmaking and triangle in gaming?
In film school, in the classes of 3D modeling, I was told that when we model something for films we maintain topology of 4 edged polygons. Any polygon which has more or less than 4 edge/vertex is ...
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1
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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 ...
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2
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How to achieve gimbal lock with Euler angles?
I was studying about Euler angles and I came across the problem gimbal lock which can occur by using Euler angles. In gimbal lock we lose one axis of rotation.
But how? And when does it happen? On ...
6
votes
1
answer
338
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Mix shader looks wrong on my path tracer
I apologize if my methods seem way off because this is my first time trying to build a path tracer and I'm struggling quite a bit. Currently, I am trying to mimic the "mix shader" node in Blender 3D ...
- 389
5
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1
answer
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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 ...
- 183
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1
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What formula or algorithm can I use to draw a 3D Sphere without using OpenGL? [closed]
I know that there are 3 techniques to draw 3D objects:
(1) Wireframe Modeling and rendering
(2) Additive Modeling
(3) Subtractive Modeling
Am I correct?
What formula or algorithm can I use to draw a ...
user464
4
votes
1
answer
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How to convert Euler angles to Quaternions and get the same Euler angles back from Quaternions?
I am rotating n 3D shape using Euler angles in the order of XYZ meaning that the object is first rotated along the X axis, then Y...
- 241
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4
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How to build a 3d model from 2d pictures
I have a series of MRI images. I want to build a 3D model out of it, which not only presents the surface, but also contains the inside structures. What kind of photogrammetry based method can realize ...
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2
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Minimum requirements to uniquely represent a 3D object in space
Let's assume we have a 3D object (in 3D space). We get a single representation vertex from this whole 3D object. Given the fact that the object can be moved and rotated in the space in any direction, ...
- 229
3
votes
1
answer
652
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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 ...
user17337
3
votes
1
answer
1k
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Rotation matrix for a 3D object in space
This is the follow-up question from here: Minimum requirements to uniquely represent a 3D object in space
Assume I have 3 original points in a 3D object (in 3D space) as ...
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2
votes
1
answer
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$P^2$ 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 ...
user17337
2
votes
1
answer
253
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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 ...
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1
vote
1
answer
381
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Final transformation matrix to transform world coordinate into vrc [duplicate]
For a 3D scene in the world coordinates, its View Reference Point $\mathrm{VRP}$ is at $(5,2,1)$, and a viewer is looking towards point $A=(1,1,1)$. Construct a transform matrix which will map world ...
- 317
1
vote
1
answer
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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
...
- 127
0
votes
1
answer
204
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Convert one triangle to another in matrix4x4?
The context openGL instances learning.
I want to transform a reference triangle to another one. So final goal is to have one triangle and the instance being a transformation of that initial triangle.
...
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0
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1
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48
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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 ...
- 241
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1
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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?
- 241
0
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2
answers
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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 ...
