After discovering a global 4k height map online, I was eager to create a model of Earth using it. Fortunately, I stumbled upon an open-source script that promised to do just that.
function createGeometryFromMap() {
var depth = 512;
var width = 512;
var spacingX = 3;
var spacingZ = 3;
var heightOffset = 2;
var canvas = document.createElement('canvas');
canvas.width = 512;
canvas.height = 512;
var ctx = canvas.getContext('2d');
var img = new Image();
img.src = "assets/earth.jpg";
img.onload = function () {
// draw on canvas
ctx.drawImage(img, 0, 0);
var pixel = ctx.getImageData(0, 0, width, depth);
var geom = new THREE.Geometry;
var output = [];
for (var x = 0; x < depth; x++) {
for (var z = 0; z < width; z++) {
// get pixel
// since we're grayscale, we only need one element
var yValue = pixel.data[z * 4 + (depth * x * 4)] / heightOffset;
var vertex = new THREE.Vector3(x * spacingX, yValue, z * spacingZ);
geom.vertices.push(vertex);
}
}
// creating triangles from vertices
for (var z = 0; z < depth - 1; z++) {
for (var x = 0; x < width - 1; x++) {
var a = x + z * width;
var b = (x + 1) + (z * width);
var c = x + ((z + 1) * width);
var d = (x + 1) + ((z + 1) * width);
var face1 = new THREE.Face3(a, b, d);
var face2 = new THREE.Face3(d, c, a);
face1.color = new THREE.Color(scale(getHighPoint(geom, face1)).hex());
face2.color = new THREE.Color(scale(getHighPoint(geom, face2)).hex())
geom.faces.push(face1);
geom.faces.push(face2);
}
}
geom.computeVertexNormals(true);
geom.computeFaceNormals();
geom.computeBoundingBox();
var zMax = geom.boundingBox.max.z;
var xMax = geom.boundingBox.max.x;
var mesh = new THREE.Mesh(geom, new THREE.MeshLambertMaterial({
vertexColors: THREE.FaceColors,
color: 0x666666,
shading: THREE.NoShading
}));
mesh.translateX(-xMax / 2);
mesh.translateZ(-zMax / 2);
scene.add(mesh);
mesh.name = 'valley';
};
}
function getHighPoint(geometry, face) {
var v1 = geometry.vertices[face.a].y;
var v2 = geometry.vertices[face.b].y;
var v3 = geometry.vertices[face.c].y;
return Math.max(v1, v2, v3);
}
Despite successful attempts with the Grand Canyon and Hawaii heightmaps provided, my own global heightmap didn't yield desired results.
This is the terrain of Grand Canyon:
https://i.sstatic.net/9MOTO.jpg
This is the global heightmap that I am using:
https://i.sstatic.net/ZqZ6i.jpg
And this is the result I am getting for the 3D terrain of the world:
https://i.sstatic.net/kCPOg.jpg
It's clear that something is off, as the outcome doesn't resemble our planet at all.