如何使用 ThreeJS 在 3D 球体上 plot 点

Question

I just recently started delving into ThreeJS. Currently I'm trying to plot a point on a sphere but it appears to be plotting in the southern hemispehre instead of the northern hemisphere. Vertically, it looks to be in the correct spot just on the bottom of the sphere instead of the top. I grabbed some code from this answer: https://stackoverflow.com/a/8982005/738201

In the image the yellow line with the red box is my plotted point. It should be in the upstate NY region instead of where it is now.

And lastly, the code.

function xyz(lat, lon){
    var cosLat = Math.cos(lat*Math.PI/180.00);
    var sinLat = Math.sin(lat*Math.PI/180.00);
    var cosLon = Math.cos(lon*Math.PI/180.00);
    var sinLon = Math.sin(lon*Math.PI/180.00);
    var r = sphere.geometry.radius; //50

    var coords = {};
    coords.x = r * cosLat * cosLon;
    coords.y = r * cosLat * sinLon;
    coords.z = r * sinLat;

    console.log(coords);

    return coords;
}

// Lat/Lon from GoogleMaps
var coords = xyz(42.654162, -73.699830);
// returns {x: 10.321018160637124, y: -35.29474079777381, z: 33.878575178802286} 

I suspect that the issue may be using 2D coords on a 3D sphere but if so, I'm not quite sure how to rectify that.

Answer 1

Try this, It will help to use directly lat and long on the map

function calcPosFromLatLon(phi, theta){
let lat = (90 - phi) * (Math.PI/180);

let lon = (theta + 180) * (Math.PI/180);

const x = -(Math.sin(lat)* Math.cos(lon))
const z = Math.sin(lat) * Math.sin(lon)
const y = Math.cos(lat)
}
calcPosFromLatLon(//coordinates here//)