What is 3d: Definition and 1000 Discussions

In 3D computer graphics, 3D modeling is the process of developing a mathematical coordinate-based representation of any surface of an object (inanimate or living) in three dimensions via specialized software.Three-dimensional (3D) models represent a physical body using a collection of points in 3D space, connected by various geometric entities such as triangles, lines, curved surfaces, etc. Being a collection of data (points and other information), 3D models can be created manually, algorithmically (procedural modeling), or by scanning. Their surfaces may be further defined with texture mapping.

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  1. BillTre

    Art How Does Henry Segerman Combine Mathematics and Art in 3D Printing?

    Here are several 3D printer art creations by Henry Segerman I came across on the Shapeways site. I found them interesting. I especially liked the ones that projected interesting shadows when illuminated from within (like a lamp).
  2. H

    Finding ez: Solving a 3D Vector Equation

    Homework Statement Find the value of ez if e = 1/3i + 2/3j + ezk Homework Equations Any help? The Attempt at a Solution Have no idea where to start
  3. G

    3D geometry parallelepiped problem

    Homework Statement [/B] Given a rectangular parallelepiped ABCDEFGH, the diagonal [AG] crosses planes BDE and CFH in K and L. Show K and L are BDE's and CFH's centres of gravity. I think I have understood the problem, could you verify my demo please ? Thanks Homework Equations The Attempt at...
  4. V

    B Compute Angle Between Multiple 3d Vectors

    Imagine a point with n vectors (all with equal magnitude) coming out from that point that equally cancel each other out in magnitude. How would you calculate the equal angle between n vectors? For example: 2 vectors (equal magnitudes) coming from one point that cancel each others magnitude...
  5. Kara386

    Calculating 3D Density of States for a Dispersion Relation | Homework Solution

    Homework Statement Calculate the single-particle density of states ##g(\epsilon)## for the dispersion relation ##\epsilon(k) = ak^{\frac{3}{2}}## in 3D. Use ##g(k) = \frac{Vk^2}{2\pi^2}##. Homework EquationsThe Attempt at a Solution This question is worth lots of marks. My solution is a few...
  6. G

    MHB Can anyone tell me the real names of these 3D shapes?

    I know cylinder, cone and cube, but can't think of the names for the last two. I know this is a very basic question that I should know...but I am blanking.
  7. M

    Min. distance from a point to a line in 3d

    Homework Statement There's a person on the ground in (0,0,0). An object comes from the sky and hits the ground at (a,b,0), but continues propagating, that is, it does not stop. I need to find the minimum distance between the person and the object. All we know is that the person is in (0,0,0)...
  8. J

    I Solving the 3D Poisson Equation Using Finite Difference/Volume

    Hi, I'm attempting to solve the 3D poisson equation ∇ ⋅ [ ε(r) ∇u ] = -ρ(r) Using a finite difference scheme. The scheme is simple to implement in 3D when ε(r) is constant, and I have found an algorithm that solves for a non-constant ε(r) in 2D. But I am having trouble finding an algorithm...
  9. E

    MATLAB Plotting graph 3D minimization

    Hi to everyone, I'm trying to plot a 3D graph on MATLAB but I do not know how. The function that I want to plot is: y=fminbnd(@(x) wei(x,shape,scale,tw,tf),x0,x1). I would like to plot the minimization of the function wei (y) in function of the shape and the scale. Wei is a function that I...
  10. P

    Characteristics of a 3D Bioprinter

    Hi! I'm looking for anyone that has had experience with 3d Bioprinters. At the same time, I'm looking for the characteristics it needs to have in order to function without a sterile hood. Factors such as sterilization, CO2, and humidity concentration. For example, for sterilization, I have...
  11. rrw4rusty

    I need a 3D map of the universe out to 400 ly....suggestions?

    Hello, I'm a sci-fi author and need to plot a course with distances and galaxy (cluster and super cluster) stop overs between the Coma Wall, Earth and the Great Attractor. I've looked at a few online 3D universe maps and 2D maps but have not found anything ideal. Any suggestions? Thanks so...
  12. J

    Statics: 3D Equilibrium Problem r X F or Fd?

    Homework Statement The 25-kg rectangular access door is held in the 90° open position by the single prop CD. Determine the force F in the prop and the magnitude of the force normal to the hinge axis AB in each of the small hinges A and B.[/B] Homework Equations ΣF=0 ΣM=0 [/B]The Attempt at...
  13. P

    How to get the equation for 3D projectile motion?

    Hey guys, so I'm currently writing a math exploration paper on modelling the optimal tennis serve. I am using Geogebra and I was wondering if you could help me come up with the equation that will help model the trajectory of the tennis ball over time given the following conditions: 1. Initial...
  14. D

    Finding the curvature of a space curve

    Homework Statement Find the curvature of the car's path, K(t) Car's Path: r(t) = \Big< 40cos( \frac {2 \pi}{16}t ) , 40sin( \frac {2 \pi}{16}t ), \frac{20}{16}t \Big> Homework Equations K(t) = \frac { |r'(t)\:X \:r''(t)|}{|r'(t)|^3 } The Attempt at a Solution This is part of a massive 6...
  15. M

    I What will be the 4th axis of a 3d curl?

    Suppose we have do a curl of two 2-d vectors... we get the 3rd axis about which it is rotating. But when we do the curl of two 3-d vectors.. we get a answer like x-y plane is rotating wrt z axis, y-z plane rotating wrt to x-axis and similarly x-z plane rotating wrt to y axis. My question is...
  16. T

    Can a 3D printer print its own components?

    Could a 3D printer print its own ink, plastic filament, motors or anything / everything else that it uses to operate and print?
  17. S

    A ?Gravity in 3D: Computing Degree of Freedom

    Dear all can anyone help me to understand why gravity in 3 dim doesn't have local degree of freedom. How can i compute the degree of freedoms for gravity in and dimension D. If i consider massless gravity in 3d is the graviton propagating
  18. F

    A 3D oscillator trapped away from centre

    The spherical oscillator problem is for a potential centered at the origin.. but what if the particle is confined to oscillate at a small shift by a small (not infinite) barrier? The potential is now centered about the new position.. Could someone please suggest a way to solve the problem for...
  19. E

    I Proportion in 2D and 3D static equilibrium?

    If you were to look at a simple 2D or 3D static equilibrium diagram, where a mass is suspended by multiple ropes at different angles, my gut feeling is that there is a fairly simple proportion between the distance between the center of mass and the rope (the distance created opposite of the...
  20. Drakkith

    Directional Derivative at an Angle with a 3d Gradient

    Homework Statement Find the directional derivative using ##f\left(x,y,z\right)=xy+z^2## at the point (4, 2, 1) in the direction of a vector making an angle of ##\frac{3π}{4}## with ##\nabla f(4, 2, 1)##. Homework Equations ##f\left(x,y,z\right)=xy+z^2##The Attempt at a Solution I found the...
  21. Y

    Constant angular acceleration in 3D?

    In 1-dimensions, the final orientation after undergoing constant angular acceleration is: \theta_f = \theta_0 + \omega_0 t + 0.5 \alpha t^2 What is an analogous equation in the 3D case? In other words, if I know the initial orientation (say, as a quaternion), angular velocity (as a 3-vector...
  22. O

    I Harmonic Oscillator in 3D, different values on x, y and z

    Hi, For a harmonic oscillator in 3D the energy level becomes En = hw(n+3/2) (Note: h = h_bar and n = nx+ny+nz) If I then want the 1st excited state it could be (1,0,0), (0,1,0) and (0,0,1) for x, y and z. But what happens if for example y has a different value from the beginning? Like this...
  23. Alex Katko

    What variables are needed to find a moment?

    Homework Statement You wish to find the moment at the origin produced by a force, ̅F= {Fi}̂, that is applied at r= {̂ai+bj +ck ̂}. Which variables (F,a ,b,c , ) do we need to know to find a numerical answer? Explain using math and figures. Homework Equations Mo = r x F The Attempt at a...
  24. C

    MHB Vector in 3d with given by magnitude and angle

    Dear everyone,Direction Write the vector in component form. v lies in the yz planeplane, has magnitude 2, and makes an angle of 30 degrees with the positive y axis. Work I know that the x component is zero. <0,v1,v2​> Thanks Cbarker1
  25. Andreas C

    B Any 3d physics modelers/simulators?

    Is there any good, preferably available for macs, and much preferably free 3d physics simulators, in the spirit of Algodoo, or something similar? I have found Algodoo very enjoyable to play around with and very useful to help visualize certain systems and "confirm" any equations I derive for...
  26. dreens

    I Orthogonal 3D Basis Functions in Spherical Coordinates

    I'd like to expand a 3D scalar function I'm working with, ##f(r,\theta,\phi)##, in an orthogonal spherical 3D basis set. For the angular component I intend to use spherical harmonics, but what should I do for the radial direction? Close to zero, ##f(r)\propto r##, and above a fuzzy threshold...
  27. mdh321

    IMAX 3D vs RealD 3D: Worth It for Azy Eye?

    I know I'm not in the right space for thise, nor smart enough to be here, but iplan on seeing Suicide Squad Friday at IMAX. Icant use those red and green glasses they have because I have a azy eye and the don't work compatibly with each other. I just heard of IMAX RelD 3D and was wondering if...
  28. T

    I Explore the Immense Universe with the Incredible 3D Map | CS Monitor

    There are links in the article to more science-oriented reports. http://www.csmonitor.com/Science/2016/0715/Scientists-create-huge-3-D-map-of-universe-validating-Einstein-s-theories That would be a great use for some of those Virtual Reality goggles.
  29. K

    Is ψ(x)ψ(y)ψ(z) a solution to the isotropic harmonic oscillator potential?

    Homework Statement An isotropic harmonic oscillator has the potential energy function U = 0.5 k (x²+y²+z²). (Isotropic means that the force constant is the same in all three coordinate directions.) (a) Show that for this potential, a solution to the three dimensional time-independent...
  30. B

    I Exploring the 3D Nature of Black Holes

    So having considered the classical depiction of a black hole resembling a whirlpool, my thought process is that a black hole must be a 3-d phenomenon. Therefore I can not see how a event horizon/swirlpool model could be plausible unless the centre of a black hole was spinning and literally was...
  31. T

    B From a 4D perspective would 3D infinity exist?

    From the perspective of a 4D observer would 3D infinity appear to exist? Why/why not?
  32. M

    I Density of states from 3D to 2D

    Hi, I know how to calculate density of states for both cases, but it is not clearly to me how I can go from 3D case to 2D. I have energy from infinite potential well for 3D $$E=\frac{\hbar \pi^2}{2m}(\frac{n_x^2}{l_x}+\frac{n_y^2}{l_y}+\frac{n_z^2}{l_z})$$ let make one dimension very small...
  33. U

    I Spherical coordinates via a rotation matrix

    First, I'd like to say I apologize if my formatting is off! I am trying to figure out how to do all of this on here, so please bear with me! So I was watching this video on spherical coordinates via a rotation matrix: and in the end, he gets: x = \rho * sin(\theta) * sin(\phi) y = \rho*...
  34. washer

    3D Equilibrium of 4-wheel support

    Homework Statement The plate has a dimension of 460mm X 260mm, subjected to a central load of 400N. Determine the reaction A and B, each representing a roller support as a wheel, located at the center of one edge. (opposite blue arrows have the same resultant value.) Are they the same ? If not...
  35. Artlav

    Ray transformation of a 3d lens?

    Greetings. I'm working on a raytracer, and got stuck with trying to model a lens analytically. Given is a thin lens at position p with the axis n, radius r and a focal distance f, a ray hits it at position p1 going in the direction d. Which way would the ray be going on the other side of the...
  36. Bill McKeeman

    A Exploring Galactic Rotation Data in 3D: A Search for Peculiar Motion

    Does anyone know of galactic rotation data (any galaxy) of the following form: For simplicity assume an [x y z] coordinate system with the origin in the center of the galaxy and [x y] representing the plane of rotation. At any point [x y z] there is a corresponding velocity vector [vx vy vz]...
  37. G

    Possibilities and limitations of 3d printers

    I read more and more news about what 3d printers created. I wonder about two things. Can they create engine parts that has to be durable, withstand big stress? Could they do it cheaper than old fashioned ways of forging metal? Also they write about 3d printed organs, but are they rather like...
  38. Y

    L, m quantum numbers of 3D oscillator

    Homework Statement 6 degenerate energy states at E=7/2 h-bar w in isotropic 3D harmonic oscillator. pick one possible state( for example, (nx,ny,nz)=(1,0,1)), and find possible l, m quantum numbers you may use orthonormality of spherical harmonics[/B] Homework Equations pick one possible...
  39. chwala

    Vector Geometry: Solving for Position Vectors and Equations in 3D

    Homework Statement The points A,B and C have position vectors , relative to the origin O given by ## OA= i+2j+3k, OB=4j+k , OC=2i+5j-k.## A fourth point D is such that the quadrilateral ABCD is a parallelogram. i) Find the position vector of D and verify that the parallelogram is a Rhombus...
  40. kelvin490

    MATLAB How to set zero value boxes transparent in 3D plots?

    I used a function called ind2patch to make a big 3D block which contains a number of smaller blocks in 3 dimensions. Each small block has a value which the magnitude is represented by a color.One example is shown below: However, most of the boxes have very low or zero value and I don't need to...
  41. M

    Modeling 2D vs. 3D Flow in a Circular Pipe

    Hi everyone! I have the following problem. I have a two phase flow in a circular pipe and I want to model it. I need to decide and justify whether the model should be 2D or 3D. For the moment, I can say only one thing: considering z-axis in the length direction (that it is the dominant one) I...
  42. ImShiva

    A Why Energy of 4s is higher than 3d?

    According to Aufbau principle energy of 3d should be greater than 4s but here 4s is having higher energy. Please anyone explain this.
  43. F

    Distinct modes of oscillation in a 3D crystal lattice

    Homework Statement Silicon crystalises in a cubic structure whose lattice is face-centred, with a basis [000],[1/4,1/4,1/4]. How many optic/acoustic modes are to be found in the phonon dispersion diagram for silicon. How many distinct branches would you expect along the [100] direction...
  44. Molay Mahdi

    MATLAB How to visualize 3D solution on matlab?

    I just want to know how to visulize 3D solution in MATLAB by different ways So please I need some help.
  45. F

    Volume of a Solid- 3D Calculus

    Homework Statement Find the volume of the given solid. Bounded by the planes z = x, y = x, x + y = 5 and z = 0 Homework Equations V =...
  46. Einstein's Cat

    I Papers on 4D ball through 3D space

    Could anyone please recommend any papers that describe the path of a 4D ball through 3D space?
  47. goonking

    Solving 3D Statics Homework with Free Body Diagram

    Homework Statement Homework EquationsThe Attempt at a SolutionFree body diagram Setting moment at the origin = 0 (Rb X B) + (Ra X A) + (Rc X C) = 0 solving the 3 determinants and setting the coefficients of i, j, and k to 0, I get: 8Bz - 10 Cy = 0 -12 Az + 10 Cx = 0 12 Ay - 8Bx = 0 I...
  48. V

    I 3D space curvature visualization

    I want to program space curvature vizualizaion. I want to have an observer as a player that moves in 3d curved space and surrounding objects that will show curvature by distortion when player passes near them. I am concerned about some points: 1. What curvature to choose in order to experience...
  49. Ben Wilson

    Efficient 3D Inverse Fourier Transform on FORTRAN Code with Chi Array

    Hi, I have a FORTRAN code with an array called Chi that I want to run an inverse FT on. I have defined two spaces X and K which each consist of 3 vectors running across my physical verse and inverse space. My code (If it works??) is extremely slow and inefficient (see below). What is the best...
  50. DianaHerberg

    B Find 3D Models of Waves | Get Creative with 4D Displays

    I am looking for 3D (or 4D, etc.) images of waves (such as light or sound), but seem to be having difficulty locating such models. Can someone please direct me to this kind of display, or is it not something being currently done?
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