Questions tagged [geometric-transform]
The geometric-transform tag has no usage guidance.
98
questions
5
votes
2answers
196 views
Why can't an annulus be mapped as a rectangle
The following code is used to map an annulus to a rectangle:
...
asked Mar 19 at 3:50
Please Correct GrammarMistakes
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8
votes
2answers
561 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 ...
0
votes
0answers
23 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
votes
0answers
32 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
64 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
159 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
136 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
53 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
66 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
57 views
Difficulty Displaying an Untransformed and Transformed Graphics3D Object with Show
I would like to illustrate a sequence of translations and rotations relative to the initial coordinate system simultaneously with multiple views using Manipulate. I discovered that there are some ...
2
votes
2answers
100 views
1
vote
1answer
94 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
356 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, π/2}]
I want to ...
5
votes
2answers
235 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
votes
0answers
102 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
63 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
votes
1answer
88 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
vote
1answer
65 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
120 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
682 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
121 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
88 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
votes
0answers
145 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
137 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
235 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 ...
1
vote
1answer
345 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 ...
6
votes
1answer
390 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
222 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
329 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 ...
1
vote
0answers
59 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
487 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
139 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
149 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 Möbius strip?")
...
7
votes
2answers
157 views
DiscretizeGraphics issues with transformations
I noticed DiscretizeGraphics does not work correctly with transformed Graphics such as
...
4
votes
1answer
301 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!
...
2
votes
1answer
142 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 ...
1
vote
1answer
201 views
Extracting scaling factor and rotation angle from TransformationFunction
I have successfully transformed two 2D data sets (data1, data2) by using ...
10
votes
1answer
116 views
What does the alignment error returned from FindGeometricTransform measure?
FindGeometricTransform returns "the alignment error together with the transformation function." How is the alignment error computed?
I ask because if you iterate <...
-4
votes
1answer
169 views
Mathematica Module for Denavit-Hartenberg Parameters to Transformation Matrix
I need to write a Mathematica module to get a 4*4 transformation matrix given the Denavit-Hartenberg parameters of the manipulator. How do I go about it?
2
votes
1answer
158 views
Get CoordinateTransformData from TransformationFunction?
I can define a composite symbolic transformation as e.g.
tf = RotationTransform[θ, {0, 0, 1}] @* TranslationTransform[{0, 0, 1}]
which returns (in ...
1
vote
0answers
360 views
Apply a four-point transform crop to an image
I am attempting to straighten and crop an image by using Edge Detection. The original image looks like this. By using edge detection and finding the max and min values for the points regarding the ...
5
votes
0answers
202 views
BSpline: construct surface from enclosing contours
I'm aiming to construct 3D shape from profiles (typical archaeological drawing stuff: front, side and top profiles views). Through several operation, I now have BSpline curves, which should define ...
6
votes
1answer
249 views
Plot points shifted (a lot) in output and PNG export but not in PDF export
Bug introduced in 8 or earlier and fixed in 12.0.0
Consider the following code:
...
4
votes
1answer
93 views
Using RotationTransform and Table
I created a small animation, very simple of course, that works very well.
...
1
vote
1answer
79 views
Implementation of ShearingMatrix
How does Mathematica implement ShearingMatrix?
In other words given the parameters $\theta$, $n$ and $v$, what is the formula behind it?
2
votes
2answers
259 views
Images and Linear Transformations
I was playing around with some of the Image processing commands like ImageRotate.
I thought it would be fun to try and make up some basic linear transformation rules - starting in 2D and then going ...
13
votes
1answer
618 views
How to align a poster?
I'd like to crop and transform out the magazine cover so that it is rectangular.
I read the docs for ImagePerspectiveTransformation, and here's where I got to. ...
1
vote
2answers
182 views
13
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2answers
3k views
Application of the projection matrix: Removing perspective distortion
I know that there are many posts about image treatment, but I still have trouble with this little challegene.
Baisically I want to remove the perspective distorsion form this image:
(source: http://...
