Published
Edited
Feb 18, 2020
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mu0 = Math.radians(start[0])
m_per_deg_lat = 111132.92 - 559.82 * Math.cos(2*mu0) + 1.175 * Math.cos(4*mu0) -0.0023 * Math.cos(6*mu0)
m_per_deg_long = 111412.84 * Math.cos(mu0) -93.5* Math.cos(3*mu0) + 0.118 * Math.cos(5*mu0)
function getLatLong(flatearth_pos, lat_long_origin, rotation, href) {
// ellipsoid planet defined by flattening (WGS84).
//var f = 1/298.257223563;
// planetary equatorial radius (WGS84)
//var Re = 6378137;
var psi = Math.radians(rotation)
var x = flatearth_pos[0]
var y = flatearth_pos[1]
var z = flatearth_pos[2]
//var mu0 = Math.radians(lat_long_origin[0])
//var m_per_deg_lat = 111132.92 - 559.82 * Math.cos(2*mu0) + 1.175 * Math.cos(4*mu0) -0.0023 * Math.cos(6*mu0)
//var m_per_deg_long = 111412.84 * Math.cos(mu0) -93.5* Math.cos(3*mu0) + 0.118 * Math.cos(5*mu0)
//rotate
//begin by transforming the flat Earth x and y coordinates to North and East coordinates, through a simple rotation.
// (These will still be in meters.)
var N = Math.cos(psi) * y - Math.sin(psi) * x
// sin(psi) * 0 + cos(psi) * 200
var E = Math.sin(psi) * y + Math.cos(psi) * x
var Ndeg = N / m_per_deg_lat
var Edeg = E / m_per_deg_long
//translate
var lat = lat_long_origin[0] + Ndeg
var long = lat_long_origin[1] + Edeg
var alt = href + z
//return [[lat,long, alt],[lat0,long0],[x,y,z],[N,E],[m_per_deg_lat,m_per_deg_long],[Ndeg,Edeg]]
return [lat,long,alt]
}
function getXYZfromLLA(LLA, lat_long_origin, rotation, href) {
var Ndeg = LLA[0] - lat_long_origin[0]
var Edeg = LLA[1] - lat_long_origin[1]
var psi = Math.radians(-rotation)
// calculate meter coordinates
var N = Ndeg * m_per_deg_lat
var E = Edeg * m_per_deg_long
//rotate:
var y = Math.cos(psi) * N - Math.sin(psi) * E
var x = Math.sin(psi) * N + Math.cos(psi) * E
var z = LLA[2] - href
return [x,y,z]
}
LLresult = getLatLong([50,200,10], start, rotation, href)
XYresult = getXYZfromLLA(testLLA,start,rotation, href)
show(XYdata)
trackLLA = trackXYZ.map(function(point) {
var LLA = getLatLong(point, start, rotation, href)
return LLA
})
d3 = require("d3@5")
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
