Mastodon

MATLAB Example to Illustrate John Aitchison’s Log-Ratio Transformation, Part 3

A while back I wrote a post about John Aitchison’s Log-Ratio Transformation, Part 1, in the time domain and today Part 2 in the frequency domain. Here’s Part 3 with a MATLAB demonstration of a nice Aitchison example presented in an extended abstract by Pawlowsky-Glahn and Egozcue (2013). Continue reading “MATLAB Example to Illustrate John Aitchison’s Log-Ratio Transformation, Part 3”

MATLAB Example to Illustrate John Aitchison’s Log-Ratio Transformation, Part 2

A while back I wrote a post about Aitchison’s log-ratio transformation. It was about eliminating the dilution effect of an element 1c on elements 1a and 1b by dividing 1a/1b or log(1a/1b). One can show the effect of the log-ratio transformation also very nicely in the spectral domain. Here is an example. Continue reading “MATLAB Example to Illustrate John Aitchison’s Log-Ratio Transformation, Part 2”

Calculating 3D Point Clouds From 3D Scanning Outputs

When I was working on the student experiments for the book Signal and Noise in Geosciences (Springer 2021), there was an inexpensive 3D scanner available – right up until that moment when I got the money to actually buy it. The company Hewlett Packard bought the smaller manufacturing company and stopped the production of the cheap scanner. HP was selling much more expensive 3D scanners at that time. Now there is a inexpensive 3D scanner again, the Revopoint MINI, and I just got one. Here are the first results, scanning with the company’s software, then importing, processing and displaying the point cloud with texture with MATLAB. Continue reading “Calculating 3D Point Clouds From 3D Scanning Outputs”