The Javascript D3.Js geoOrthographic() function gives us the azimuthal orthographic projection. It is useful when we want to see earth as 3D object and its hemispheres separately.
Syntax:
d3.geoOrthographic()
Parameters: This method does not accept any parameters.
Return Value: This method creates and returns geoOrthographic() projection from given JSON data.
Let us look at an example to understand how we can use geoOrthographic() function.
Example 1: Orthographic projection having no rotation
HTML
<!DOCTYPE html> <html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width,
initial-scale=1.0" />
<script src=
</script>
</head>
<body>
<div>
<svg width="1200" height="850">
</svg>
</div>
<script>
var svg = d3.select("svg"),
width = +svg.attr("width"),
height = +svg.attr("height");
// The orthographic Earth projection
// Center(0,0) and no rotation
var projection = d3.geoOrthographic()
.center([0, 0])
.scale(250)
.clipAngle(90 )
.translate([width / 2, height / 3])
.rotate([0,0])
// Loading data from json
d3.json("https://raw.githubusercontent.com/"
+"epistler999/GeoLocation/master/world.json",
function (data) {
// Draw the map
svg.append("g")
.selectAll("path")
.data(data.features)
.enter().append("path")
.attr("fill", "green")
.attr("d", d3.geoPath()
.projection(projection)
)
.style("stroke", "#ffff")
})
</script>
</body>
</html>
|
Output:
Example 2: Orthographic projection having Rotation
HTML
<!DOCTYPE html> <html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content=
"width=device-width,initial-scale=1.0" />
<script src=
</script>
</head>
<body>
<div>
<svg width="1200" height="850">
</svg>
</div>
<script>
var svg = d3.select("svg"),
width = +svg.attr("width"),
height = +svg.attr("height");
const config = {
speed: 0.010,
verticalTilted: -10,
horizontalTilted: 0
}
// The orthographic Earth projection
// Center(0,0) and no rotation
var projection = d3.geoOrthographic()
.center([0, 0])
.scale(250)
.clipAngle(90 )
.translate([width / 2, height / 3])
.rotate([0,0])
const path = d3.geoPath().projection(projection);
// Calling rotate() function for rotation of globe
Rotate();
// Loading data from json
d3.json("https://raw.githubusercontent.com/"
+"epistler999/GeoLocation/master/world.json",
function (data) {
// Draw the map
svg.append("g")
.selectAll("path")
.data(data.features)
.enter().append("path")
.attr("fill", "grey")
.attr("d", d3.geoPath()
.projection(projection)
)
.style("stroke", "#ffff")
})
// Function to rotate() projection of globe.
function Rotate() {
d3.timer(function (elapsed) {
projection.rotate(
[config.speed*elapsed-120,
config.verticalTilted,
config.horizontalTilted]);
svg.selectAll("path").attr("d", path);
});
}
</script>
</body>
</html>
|
Output: