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Anton Semechko


129 total contributions since 2010

Professional Interests: Signal/medical image processing, computational anatomy and biomechanics

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SO(3) processing utilities
Collection of functions for processing sets of 3D rotation matrices

16 days ago | 3 downloads |

Answered
PCA on high dimensional data
A 13952736-by-104 data matrix (with observations along rows and variables along columns) will take up 13952736*104*8/2^30 =...

3 months ago | 0

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Fitting scattered data to multiple cosine functions
Below is an example where I use brute-force search to find an optimal set of sinusoid parameters that best fit an unorganized da...

3 months ago | 1

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imshow() not working
Use syntax: imshow(im,[]) when im has non-integer format. Or just do this: im = imread('/MATLAB Drive/My Project/ima...

3 months ago | 0

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distance of points to points calculation
Use <https://www.mathworks.com/help/stats/knnsearch.html#namevaluepairarguments 'knnsearch' function>. For example: [idxA,D_...

3 months ago | 0

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How is the number of bins chosen with the auto binning algorithm in histcounts?
'histcounts' first estimates width of the histogram bins using 'scottsrule': rawBinWidth = 3.5*std(data)/(numel(data)^(1/3...

3 months ago | 0

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Barycentric Coordinates of a spherical triangle
This can be done in four steps: 1) Compute linear transformation (T) that maps triangle A to its counterpart B on the sphere....

3 months ago | 0

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How do I use a .lut file (or the equivalent in MATLAB) to reference pixels in a grayscale image and assign them new values for pseudocoloring based on the LUT?
There is a Matlab function that maps gray values to RGB values using custom made look-up-tables. Its called 'ind2rgb': <https://...

3 months ago | 0

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Transformation of the complex plan: Conformal Mapping
Modified code ('conformal_map_demo') is attached below. In principle, this piece of code should should allow you to visualize an...

3 months ago | 1

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How to sum each column element of one matrix with all column elements of another matrix?
Do kron([a b;c d],[1;1]) + kron([1;1],[i j;k l]) Here is an example using symbolic expressions syms a b c d i j k l...

4 months ago | 0

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Generating sets of non repeating random numbers
Here is an example: S=reshape(randperm(40),[],4); All elements in S will be in the range [1 40] and unique. From this it...

4 months ago | 1

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3D plane plotting restricted by 3 points
Equation of a plane is determined uniquely by any 3 (noncollinear) points lying on the plane. Based on your question, it sounds ...

4 months ago | 0

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Could anyone help me with extracting similar features( to be used as corresponding points)in two images which need to be registered together?
Hey, Poupack, here is <https://drive.google.com/open?id=1SRXAVFkbHPfQ9jLjsFL-fkfWz2KrKJAO link> to a function ('pairwise_his...

4 months ago | 0

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How can I extract the slices of a 3D matrix in x-direction from a 3D matrix?
Suppose you have G, which is a Y-by-X-by-Z 3D array, then i-th xy slice: G_yx=G(:,:,i); % Y-by-X array i-th xz slice...

4 months ago | 1

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Multivariate nonlinear regression model fitting
If the function you are trying to fit is linear in terms of model parameters, you can estimate these parameters using linear lea...

4 months ago | 1

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How to export 3D spheres (3D plot) generated in Matlab to ANSYS or Abaqus. ?
The builtin 'ellipsoid' and 'sphere' functions produce bad quality meshes (in terms of element shapes and connectivity of the ve...

4 months ago | 0

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Is there a way to open music and play it?
Yeah, there is a way. Here is an example: % Get sample audio file from the web [y,Fs]=webread('http://www.worldnationala...

4 months ago | 0

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Answered
How do I compute the maxpool of a image? Let us say stride of 2,2 on a mxn matrix?
Here is an example: % Sample image im=imread('cameraman.tif'); % sample image % 4 pixels comprising non-overlappi...

4 months ago | 0

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How do I plot a plane that has points of different values?
Actually, based on the sample picture you provided, you have a total of 17x21 grid points, and total number of cells in the g...

4 months ago | 2

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Obtain Number of Pixels in Area Around Binary Image Object
To distinguish between points/pixels inside the ellipse vs. those outside, you need to know parameters of the ellipse. Here is a...

4 months ago | 0

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subplot with multiple images - Pulling images from API into one figure
Hey, Vincent. Here is an example: [IM,IM_all]=PubChem_compound_image_stacking_demo; <</matlabcentral/answers/uploaded_fi...

4 months ago | 0

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How do you generate a Cumulative Histogram on R2014a?
Here is an example of how to use 'histcounts' and estimate percentiles: % Simulate data; N samples from standard Guassian P...

4 months ago | 0

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I want to plot a numerical integral in a mesh which is dependent of x and y. How can I do this?
The integrals in your equation can be evaluated analytically. Here how you can visualize C(z1,z2) and C(z1,z1): L = 20...

4 months ago | 0

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Interpolating scattered 3 dimensional data
Hi, Markus, here is a demo of how to perform linear interpolation of vector fields on a unit half-sphere: half_sphere_inter...

4 months ago | 1

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Taylor expansion with 2 variables
Taylor's theorem generalizes to multivariate functions. Formula for third order approximation of a bivariate function can be fou...

4 months ago | 0

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Troubleshooting Isosurface Rendering Code
Make sure that your 'Image' variable is cast as a double and actually has a zero level-set. Here is an example: % Samp...

4 months ago | 0

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How to find distance between two nodes? including the nodes.
Download <https://www.mathworks.com/matlabcentral/fileexchange/5355-toolbox-graph graph processing toolbox> from FEX. Use Dijks...

4 months ago | 0

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how to deal with large polygons ?
Check out 'DecimatePoly' function on FEX: <https://www.mathworks.com/matlabcentral/fileexchange/34639-decimate-polygon> Inclu...

4 months ago | 1

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Detection of line segments and length
It doesn't look very clear to me, and is maybe the reason why the Hough transform isn't generating the output you want. For exam...

4 months ago | 0

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Can I recover only the diagonal elements of A' * B with SVD vectors of A and B?
i-th diagonal of A'*B equals dot product of the i-th columns of A and B. Here is a demo showing how to recover only the diagonal...

4 months ago | 0

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