Questions tagged [geometric-transform]
The geometric-transform tag has no usage guidance.
112
questions
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2answers
95 views
Random rotation at a given angle?
I need to generate a random rotation matrix for a given angle $a$. In other words, a random $n\times n$ matrix $A$ such that for any unit-length vector $v$ the following is true.
$$v'Av\le\cos a$$
The ...
2
votes
1answer
51 views
FindGeometricTransform not working properly for a simple problem
I am surprised why FindGeometricTransform is failing to automatically register or align two sets of points that are drawn from a ...
5
votes
1answer
98 views
Nest or fold a series of geometric transforms
I have a requirement to perform a series of GeometricTransformation[]s using the AfineTransform[] function. I use these to set ...
2
votes
2answers
62 views
EulerMatrix with axes other than X, Y an Z
The Mathematica function EulerMatrix[{Alpha, Beta, Gamma},{a,b,c}] gives the Euler matrix for rotation about X, Y and Z axes. Here by choosing the order of a, b and ...
0
votes
1answer
35 views
Affine transform of sparse list (x,y,z) to a region of x^2 + y^2 + z^2 = 1.0
I have list of x,y,z points (somewhat random) that leads to the image shown below:
I am trying to map this data to essentially a sphere shape using an affine transform. My original attempt was to ...
1
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1answer
69 views
Visualizing an Affine Matrix
I have a computer graphics program that prints out affine matrices like
...
1
vote
1answer
58 views
How to modify a particular step length in a 3D random walk?
Suppose I simulate a random walk in 3D using AnglePath3D[]:
...
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0answers
27 views
How to reorient a Sphere[] and associated point based on some arbitrary axis?
Suppose I have a unit Sphere[] sitting at the center {0,0,0}, with a point on its "north pole", like this one:
...
3
votes
1answer
124 views
3
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0answers
98 views
Find nearest crop of image within another image
ImageAlign[ref, i] works well when image i is fully contained within the reference image ref,...
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0answers
14 views
How to concatenate multiple `CapsuleShape[]` while changing their size?
I am trying to create a 'chain' of capsules so that they are concatenated at certain points. Then, I want to change the size (radius, etc) of a given capsule, while preserving the relative orientation ...
0
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1answer
64 views
Need help understanding Graphics Translate
I created a star pattern that I was trying to apply to a circle of pentagons, but the Translate had a slight offset, and I don't understand why. When I drew the ...
3
votes
2answers
83 views
Region function of rotated Polyhedron
Is it possible to find the equation of the internal region of a rotated polyhedron? For example, the analytic region for a Dodecahedron is found by:
...
4
votes
2answers
211 views
Why can't an annulus be mapped as a rectangle
The following code is used to map an annulus to a rectangle:
...
8
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2answers
605 views
How to visualize a spherical mesh on a squared plane?
I need to visualize the points of a spherical mesh on a squared plane (this question is different than this one, I believe). For instance, let us first generate points ...
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0answers
33 views
How to get the transformation function from one plane to another?
Suppose I have a plane which passes through some point $(x_0,y_0,z_0)$ and has a (normalized) surface normal $n$.
Consider as an example a plane that passes through the point ...
0
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0answers
41 views
Setting the location of the origin within an image for AffineTransformation
This question is closely related to this one, but slightly different.
I want to perform several AffineTransforms on an image (myImage). For example, here is a ...
2
votes
1answer
69 views
Geometric transform of a plot with legends and title
I'm doing a ternary phase diagram, so I want to plot it in a triangle and not in a square. If I'm doing the transformation with legends it doesn't work, but if I don't put legends it does work. Why ...
1
vote
2answers
216 views
How do you implement metric tensor in Mathematica?
I'm trying to follow several tutorials on metric tensors. One of the common exercises is a polar metric. I'm stuck trying to implement this in Mathematica. According to the derivation, the polar ...
5
votes
1answer
151 views
Transforming 2D points on to a regular grid or lattice
I have a set of points in 2D generated by doing a DimensionReduce on a list of colors:
...
1
vote
1answer
63 views
Apply non-linear transformation to graphics object
I would like to define some simple geometric primitives (e.g. points and lines) and see what happens when I transform them by a non-linear transformation (in my case $(x,y)\mapsto (\sqrt x,\sqrt y)$). ...
1
vote
1answer
71 views
Translate (and scale) AnatomyData in three-dimensions
I would like to create a Graphics3D entity consisting of a human eyeball and a complex figure defined elsewhere.
(For a minimal working example, assume that the ...
2
votes
1answer
79 views
Difficulty Displaying an Untransformed and Transformed Graphics3D Object with Show
Update: This bug has been fixed
The bug has been fixed and the code below is working in $Version=12.1.1 for Microsoft Windows (64-bit) (June 19, 2020).
Original ...
2
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2answers
122 views
1
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1answer
121 views
Rotate a circle in 3D space with RotationTransform
This is related to my confusion over how to combine graphics objects and geometric objects: see Affine transformation of circular arc in 3D.
Why does evaluating the ...
6
votes
3answers
387 views
Affine transformation of circular arc in 3D
Start with a quarter-circle of radius 1 centered at the origin and lying in the $xz$-plane:
arc = ParametricPlot3D[{Cos[t], 0, Sin[t]}, {t, 0, Ļ/2}]
I want to ...
5
votes
2answers
302 views
Removing anomalous points from data
I have two sets of 2d-data points which can be transformed in each other by using a certain transformation function.
The problem is that in both data sets there are points which do not have ...
0
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0answers
134 views
Transform a field with derivatives
Given a function of Cartesian coordinates $(x, y)$ in $g(x, y) = \frac{d}{dx}f(x, y)-y\frac{d}{dy}f(x, y)$, I want to transform this expression to polar coordinates $(r,\phi)$. I saw a solution using ...
2
votes
1answer
67 views
How is the error of FindGeometricTransform calculated? [duplicate]
This question has beeen asked here but was not answered.
How is the returned error calculated?
I cannot find any information about this in the documentation of ...
0
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1answer
97 views
Transforming a conic to it's standard form
Suppose a conic is given.I need to transform it to standard form.So i tried like this:
...
1
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1answer
69 views
Sequential 3D transformations
I have a function s[x,y,z] that assumes a reference of centered at the origin and pointed along the positive z axis. Given two points, I want to rotate and translate that function such that its center ...
2
votes
1answer
128 views
How to draw a “Y” shaped branch in Mathematica?
I want to draw a Y-shaped branch in Mathematica. I am trying to draw a line of length L. In step II, I want to translate to the ending point of the line. Then I want to rotate at an angle of 45 deg to ...
4
votes
3answers
955 views
Drawing the Pursuit curves
I was reading this post on Filling Space with Pursuit Polygons. I didn't really see where the filling was, but found it quite interesting.
Then I saw these pursuit ...
0
votes
1answer
175 views
With equation of vector fields which are in cylindrical polar coordinates, how to plot 3-D vector field? [closed]
I have the equation of vector fields which are in cylindrical polar coordinates. How do I plot 3-D vector field? I never used Mathematica.
Edit2:
...
3
votes
1answer
95 views
What algorithm is used by FindGeometricTransform? [closed]
Can anyone tell me how the operation FindGeometricTransform[pts1, pts2] works (I mean inside logic of the transformation function), or where can I find such an ...
0
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0answers
161 views
Eigenvalues not invariant after similarity transformation
I have two examples of matrices that undergo a similarity transformation: a random matrix, and an exclusion-process inspired matrix. The similarity transformation $\sigma$ is given by an $L \times L$ ...
2
votes
3answers
167 views
Computing angle of rotation and scaling factor directly from given transformation matrix
I have a simple 2D transformation matrix performing rotation combined with scaling
\begin{bmatrix}
1 & 1 \\
-1 & 1
\end{bmatrix}
Where the scalar $r$ is multiplied with
\begin{...
4
votes
2answers
240 views
Rotating panels with GeometricTransformation
In the field of architecture, learning to manipulate geometry so comprehensively with Mathematica has been fun. However, I seem to have reached my limits with the following ...
5
votes
4answers
958 views
How to double (or triple) each element of equation?
x^2/3+y^2/9==1
(0.5x)^2/3+(0.5*y)^2/9==1
Looks at above two equation,I multiply 0.5 to each element of second equation,which means when plotting, each point ...
2
votes
1answer
402 views
rotate image around fixed point
How can I painlessly rotate a tiff image by some small angle around a point with specific coordinates? The image shouldn't be altered otherwise, it can be padded with zeros if necessary, and then ...
5
votes
1answer
458 views
How to transform general Ellipsoid into rotated axis-oriented one?
Recently, I discovered a long-standing bug in the rendering of Disk and Circle primitives after applying ...
13
votes
2answers
236 views
Why BoundingRegion does not work well?
Bug introduced in 8 or earlier and fixed in 12.0.0
The underlying bug is unstable and wrong rendering of Disk[] and Circle[] ...
1
vote
2answers
344 views
How to determine roll pitch and yaw/Euler angles from approximately orthogonal matrix?
I have a collection of rigid bodies, each comprising ~100 particles. Each body is defined by a list of points corresponding to the coordinates of its constituent particles. The rigid bodies are ...
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0answers
60 views
How to get explicit result of geometric transformation? [duplicate]
Seems like this simply rectangle rescale should work and return the exact coordinates of the transformed resulting rectangle (which should be ...
13
votes
2answers
513 views
Extracting data from analog screen photograph
I'm using an analog profilometer from the 1970s and need a way to digitize the data and the only way is through a photograph.
I've searched but all I could find was how to extract data from computer ...
0
votes
1answer
152 views
Rotate a RegionPlot3D
I plotted a bunch of regions using RegionPlot3D, and would need to rotate them around an a vector {0,0,1} anchored at point {5,5,5}. I tried RotationTransform, Transformed Region, and changing ...
4
votes
2answers
167 views
Performing geometric transforms on 3D text inside a Graphics3D expression
I am trying to put some 3D text inside a 3D graphics. So far I find two ways to make 3D text.
halirutan in "Rotating an image along a Mƶbius strip?")
...
7
votes
2answers
160 views
DiscretizeGraphics issues with transformations
I noticed DiscretizeGraphics does not work correctly with transformed Graphics such as
...
4
votes
1answer
304 views
Results of Rotate and Translate are not the same in 2D and 3D
I cannot understand why the same transformations in 2D and 3D do not give the similar results (flat join segment line). In 3D the segments are not joined. Please help!
...
asked Sep 6 '17 at 18:52
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2
votes
1answer
165 views
Transform a RegionFunction in ContourPlot3D
This is related to a previous question but now I would like to apply a geometric transformation to the region function first. (I am trying to paint a spot on a cylinder, where the spot is the region ...
