geo-util

JavaScript utitlities for online mapping. It includes several useful tools

projection

• Conversion between UTM and Lat/Lng, and conversion between Lat/Lng and Web Mercator UTM is probably the most used projection in GIS. In order to plot it on web maps, which are under Web Mercator, it needs to reproject it from UTM to Lat/Lng, then convert Lat/Lng to Web Mercator

samples

usage

• geoUtil.utm2Lnglat(x, y, epsg). It returns an object with latitude and longitude properties.
• geoUtil.lnglat2Utm(lng, lat). It returns an object, which has several properties, including "zone", "south", "x", "y" and "epsg".
• geoUtil.webMercator2Lnglat(x, y). It returns an array with longitude and latitude value.
• geoUtil.lnglat2WebMercator(lng, lat). It returns an array with x and y values in web mercator.

geodesic

• geodesic util tools can densify between two lng/lat value pairs. It provides methods to measure distance and area with high accuracy.

samples

usage

• geoUtil.geodesicDensify(pts). pts is an array of [x, y] values. It returns an array of [x, y] values which have been densified with geodesic curves.
• geoUtil.computeDistance(pt1, pt2, unit). pt1 and pt2 are [lng, lat] values. unit could be "miles", "kilometers", "feet", "meters", "yards", "nauticalMiles", "inches". It return the distance value in the unit. If unit it not specified, it's in miles.
• geoUtil.computeArea(pts, unit). pts is an array of [lng, lat] values. Make sure the last the first point are identical so that it's a close polygon. Unit could be "acres", "ares", "squareKilometers", "squareMiles", "squareFeet", "squareMeters", "hectares", "squareYards". Default is ares. It returns the area value in the unit.