GIS Utility Functions

milansoliya · December 27, 2024, 11:14am

Is there any function or method available in cesuim unreal or cesuim native as mentioned below ?

Distance between two cartographic point like double GeodeticDistance(double lon1, double lat1, double lon2, double , lat2) ?
Forward Azimuth between two cartographic point double ForwardAzimuth(double lon1, double lat1, double lon2, double , lat2) where out would be 0-360 from true north in degree ?
Geodetic Point calculation from distance and azimuth from reference point like GeodeticPoint(double lon, double lat, double distance, double azimuth, double resultLon, double resultLat) ??

While considering Earth Model like Ellipsoidal or Spherical ?

Kevin_Ring · January 7, 2025, 3:14am

Hi @milansoliya, welcome to the community!

We don’t currently have such functions in Cesium for Unreal.

You can find an open-source implementation of the first of these in CesiumJS:

github.com

CesiumGS/cesium/blob/main/packages/engine/Source/Core/EllipsoidGeodesic.js

import Cartesian3 from "./Cartesian3.js";
import Cartographic from "./Cartographic.js";
import Check from "./Check.js";
import defaultValue from "./defaultValue.js";
import defined from "./defined.js";
import Ellipsoid from "./Ellipsoid.js";
import CesiumMath from "./Math.js";

function setConstants(ellipsoidGeodesic) {
  const uSquared = ellipsoidGeodesic._uSquared;
  const a = ellipsoidGeodesic._ellipsoid.maximumRadius;
  const b = ellipsoidGeodesic._ellipsoid.minimumRadius;
  const f = (a - b) / a;

  const cosineHeading = Math.cos(ellipsoidGeodesic._startHeading);
  const sineHeading = Math.sin(ellipsoidGeodesic._startHeading);

  const tanU = (1 - f) * Math.tan(ellipsoidGeodesic._start.latitude);

  const cosineU = 1.0 / Math.sqrt(1.0 + tanU * tanU);

This file has been truncated. show original

That’s assuming your want the geodesic distance, which is the shortest distance between the points over the ellipsoid surface. You would create an instance of this class and then access the surfaceDistance property.

For the other two, I’m assuming you want a “constant azimuth” path, which forms a rhumb line, rather than the shortest geodesic path. If so, CesiumJS’s EllipsoidRhumbLine class will help:

github.com

CesiumGS/cesium/blob/main/packages/engine/Source/Core/EllipsoidRhumbLine.js

import Cartesian3 from "./Cartesian3.js";
import Cartographic from "./Cartographic.js";
import Check from "./Check.js";
import defaultValue from "./defaultValue.js";
import defined from "./defined.js";
import DeveloperError from "./DeveloperError.js";
import Ellipsoid from "./Ellipsoid.js";
import CesiumMath from "./Math.js";

function calculateM(ellipticity, major, latitude) {
  if (ellipticity === 0.0) {
    // sphere
    return major * latitude;
  }

  const e2 = ellipticity * ellipticity;
  const e4 = e2 * e2;
  const e6 = e4 * e2;
  const e8 = e6 * e2;
  const e10 = e8 * e2;

This file has been truncated. show original

For (2), you would construct an instance of this class by passing the two points to the constructor, and then access the heading property. For (3), you would construct an instance using fromStartHeadingInstance and then access the end property.

All of this is in JavaScript, so not usable directly, but it could be ported to C++ for use in Unreal Engine. We’d welcome a pull request for that if you’re up for it!

Topic		Replies	Views
From an origin point, calculate a new point using a bearing and length Cesium for Unreal	5	340	September 22, 2023
Distance between cartesian points CesiumJS	10	3009	August 2, 2017
WGS84.cartesianToCartographic always produces lat, lon between -2 and 2 CesiumJS	2	244	July 9, 2014
Calculate position based on direction and distance CesiumJS	3	2713	December 1, 2020
Geodetic Latitude (surface normal) CesiumJS	5	923	March 23, 2015

GIS Utility Functions

Related topics