GeoCoordinates

This package allows for simple coordinate transformation between cartesian ECEF (Earth centered, Earth fixed) coordinates and LLA (latitude, longitude, altitude) coordinates. Linear interpolation via triangular basis functions is also possible.

Geodesy.jl is recommended over this package for geographic coordinate transformations, but this package has Makie visualizations which might be of interest to some people. 🌍

Installation

• Install Julia v1.7.0 or greater from JuliaLang.org's downloads page.

• Run Julia in terminal

  • The default Github API has changed to use Personal Access Tokens, so you will need to type ENV["JULIA_PKG_USE_CLI_GIT"]=true into the REPL to import from a private repository without generating a PAT first. This is not need for public repositories.

  • The Julia package manager REPL can be accessed by typing ] into the default REPL and then add https://github.com/kathesch/GeoCoordinates.jl

  • Alternatively, you can use import Pkg; Pkg.add(url="https://github.com/kathesch/GeoCoordinates.jl")

• API references can be accessed via the help REPL by typing ? followed by the function you are interested in seeing the docstring for.

~ % julia

   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.9.0-DEV.1074 (2022-08-02)
 _/ |\__'_|_|_|\__'_|  |  Commit eedf3f150c (2 days old master)
|__/                   |

julia> ENV["JULIA_PKG_USE_CLI_GIT"]=true
(@v1.9) pkg> add https://github.com/kathesch/GeoCoordinates.jl
julia> using GeoCoordinates

API

Given coordinates in LLA, London for example, (51.5072°N, 0.12°W, 2m), we can obtain a vector of ECEF (X,Y,Z) coordinates using lla2xyz(lat, long, altitude).

Latitudes and longitudes are taken as positive degree values being North and East respectively.

julia> lla2xyz(51.5072, 0.12, 2)
3-element Vector{Float64}:
    3.9780141057281126e6
 8331.545442374172
    4.968862652915071e6

And we can then convert these back into LLA to obtain our previous input using xyz2lla(X,Y,Z).

julia> xyz2lla(ans)
3-element Vector{Float64}:
 51.5072
  0.12000000000000001
  2.0

Additionally, linear interpolation of two arrays xs and ys for some value t is possible with the lin_interp(t,xs,ys) function.

julia> xs = [1,1.1,3,4]
4-element Vector{Float64}:
 1.0
 1.1
 3.0
 4.0

julia> ys = rand(4)
4-element Vector{Float64}:
 0.8056397472418082
 0.7549247920881392
 0.5714319431723006
 0.3234866269090587

julia> scatter(xs,ys,markersize=10,xlims=(0,5))
julia> scatter!(x->lin_interp(x,xs,ys),xlims=(1,4))

Scitec Dataset Test

After installing and opening a Julia terminal, this package may be tested on a Unix Time t using scitec_data(t).

df will be the entire dataframe and includes all calculated positions, times, etc and v will be the interpolated velocity at that Unix time.

julia> df, v = scitec_data(1532334000)
julia> v
3-element Vector{Float64}:
  -995.9152687485116
 -2514.4388939752785
    55.92122005190347

Example Plots