mapnik-omnivore - npm Package Compare versions

Comparing version 2.2.4 to 3.0.0

lib/datasource-processor.js

		@@ -348,40 +348,20 @@ var fs = require('fs'),
		*/
		function getMinMaxZoomGDAL(pixelSize, center, proj, callback){
		var refFrom = new gdal.SpatialReference.fromProj4(proj);
		var refTo = new gdal.SpatialReference.fromEPSG(3857);
		var transform = new gdal.CoordinateTransformation(refFrom, refTo);
		function getMinMaxZoomGDAL(pixelSize, center, proj, callback) {
		var circumference = 40075000;

		// Grab half of pixelsize and add/subtract to center longitude to create a horizontal line
		var halfPixelsPerUnit = pixelSize[0]/2;
		var line = new gdal.LineString();
		line.points.add(center[0], (center[1] - halfPixelsPerUnit));
		line.points.add(center[0], (center[1] + halfPixelsPerUnit));
		// Transform native res pixel distance to google mercator pixel distance in meters
		try {
		line.transform(transform);
		} catch (e) {
		return callback(e);
		}
		var mercatorPixelSize = line.getLength();

		// After transforming pixelsize, earth circumference will always be in meters...?
		var circ = 40075000;
		var lat = center[1];
		var res;
		var maxzoom;

		//iterate through zoom levels to find threshold and set maxzoom
		for(var zoom = 19; zoom >=0; zoom--){
		// calculate resolution (meters/pixel) for each zoom level
		// S=C*cos(y)/2^(z+8)...from http://wiki.openstreetmap.org/wiki/Zoom_levels
		// calculates for lat north AND south of equator
		res = circ * Math.cos(lat*Math.PI/180) / Math.pow(2,(zoom+8));
		//use the source's resolution as the threshold
		if(res >= mercatorPixelSize){
		maxzoom = zoom+1;
		return callback(null, Math.max(0, maxzoom-6), maxzoom);
		}
		if (zoom <= 0) return callback(invalid('Failed to set min/max zoom'));
		}
		};
		// Create lookup table to determine max zoom level for given spatial resolution
		var zoomLevels = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19];
		var spatialResolutions = zoomLevels.map(function(z) {
		return circumference * Math.cos(0) / Math.pow(2, (z + 8));
		});

		var validSpatialResolutions = spatialResolutions.filter(function(res) {
		return res > pixelSize[0]
		});

		var maxzoom = validSpatialResolutions.length;
		var minzoom = Math.max(0, maxzoom - 6);

		return callback(null, minzoom, maxzoom);
		}
		/**
		@@ -388,0 +368,0 @@ * Detects unit type of the gdal source, using the srs/projection

package.json

		{
		"name": "mapnik-omnivore",
		"version": "2.2.4",
		"version": "3.0.0",
		"description": "Node module that returns metadata of spatial files.",
		@@ -5,0 +5,0 @@ "main": "index.js",

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