diff --git a/geo.ts b/geo.ts
new file mode 100644
index 0000000..3921af1
--- /dev/null
+++ b/geo.ts
@@ -0,0 +1,87 @@
+const EarthRadius = 6371008.8; // in meeter
+const YAxisInversion = 1;
+2;
+
+export enum Constant {
+  EarthRadiusInM = EarthRadius, //
+  EarthRadiusInFt = EarthRadius * 3.28084, //km: 6,378.137 | meters: 6378137
+  MeterToFeet = 3.28084,
+}
+
+export type Point = {
+  x: number;
+  y: number;
+};
+
+export interface LatLng {
+  lat: number;
+  lng: number;
+}
+
+export function realWorldDistance(p1: Point, p2: Point, unitPixel: { x: number; y: number }) {
+  const dx = (p2.x - p1.x) * unitPixel.x;
+  const dy = (p2.y - p1.y) * unitPixel.y;
+  const realWorldDistance = Math.sqrt(dx * dx + dy * dy);
+  return realWorldDistance;
+}
+
+/**
+ * distance between two geo coords in meeters
+ */
+export function haversineDistance(p1: LatLng, p2: LatLng): number {
+  const φ1 = toRadian(p1.lat); // phi 1
+  const φ2 = toRadian(p2.lat); // phi 2
+  const Δφ = toRadian(p2.lat - p1.lat); // delta phi
+  const Δλ = toRadian(p2.lng - p1.lng); // delta lambda
+  const a = Math.sin(Δφ / 2) * Math.sin(Δφ / 2) + Math.cos(φ1) * Math.cos(φ2) * Math.sin(Δλ / 2) * Math.sin(Δλ / 2);
+  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+
+  return c * Constant.EarthRadiusInFt;
+}
+
+export function toRadian(degrees: number) {
+  return degrees * (Math.PI / 180);
+}
+
+/**
+ * convert geo coords to image coordinates
+ */
+export function geoToImgCoord(
+  p: LatLng,
+  imgW: number,
+  imgH: number,
+  boxLeft: number,
+  boxBottom: number,
+  boxRight: number,
+  boxTop: number,
+) {
+  const xRatio = (p.lng - boxLeft) / (boxRight - boxLeft);
+  const yRatio = (p.lat - boxBottom) / (boxTop - boxBottom);
+  const pixelX = xRatio * imgW;
+  // Y-Axis Inversion i.e.  1 - yRatio, is need because
+  // image coordinates typically have the origin (0,0) at the top-left corner, with y increasing downward)
+  const pixelY = (YAxisInversion - yRatio) * imgH;
+
+  // console.log(p, imgW, imgH, boxLeft, boxBottom, boxRight, boxTop, ' = ', pixelX, pixelY);
+  return [pixelX, pixelY];
+}
+
+/**
+ * plane pixel to geo coords
+ */
+export function imgToGeoCoords(
+  p: Point,
+  imgW: number,
+  imgH: number,
+  boxLeft: number,
+  boxBottom: number,
+  boxRight: number,
+  boxTop: number,
+): LatLng {
+  const xRatio = p.x / imgW;
+  const yRatio = YAxisInversion - p.y / imgH;
+  const lng = boxLeft + xRatio * (boxRight - boxLeft);
+  const lat = boxBottom + yRatio * (boxTop - boxBottom);
+
+  return { lat, lng };
+}
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