function simplify_RDP($vertices, $tolerance)
{
// if this is a multilinestring, then we call ourselves one each segment individually, collect the list, and return that list of simplified lists
if (is_array($vertices[0][0])) {
$multi = array();
foreach ($vertices as $subvertices) {
$multi[] = simplify_RDP($subvertices, $tolerance);
}
return $multi;
}
$tolerance2 = $tolerance * $tolerance;
// okay, so this is a single linestring and we simplify it individually
return _segment_RDP($vertices, $tolerance2);
}
$pFFA = new adriangibbons\phpFITFileAnalysis(__DIR__ . $file, $options);
} catch (Exception $e) {
echo 'caught exception: ' . $e->getMessage();
die;
}
// Google Static Maps API
$position_lat = $pFFA->data_mesgs['record']['position_lat'];
$position_long = $pFFA->data_mesgs['record']['position_long'];
$lat_long_combined = [];
foreach ($position_lat as $key => $value) {
// Assumes every lat has a corresponding long
$lat_long_combined[] = [$position_lat[$key], $position_long[$key]];
}
$delta = 0.0001;
do {
$RDP_LatLng_coord = simplify_RDP($lat_long_combined, $delta);
// Simplify the array of coordinates using the Ramer-Douglas-Peucker algorithm.
$delta += 0.0001;
// Rough accuracy somewhere between 4m and 12m depending where in the World coordinates are, source http://en.wikipedia.org/wiki/Decimal_degrees
$polylineEncoder = new PolylineEncoder();
// Create an encoded string to pass as the path variable for the Google Static Maps API
foreach ($RDP_LatLng_coord as $RDP) {
$polylineEncoder->addPoint($RDP[0], $RDP[1]);
}
$map_encoded_polyline = $polylineEncoder->encodedString();
$map_string = '&path=color:red%7Cenc:' . $map_encoded_polyline;
} while (strlen($map_string) > 1800);
// Google Map web service URL limit is 2048 characters. 1800 is arbitrary attempt to stay under 2048
$LatLng_start = implode(',', $lat_long_combined[0]);
$LatLng_finish = implode(',', $lat_long_combined[count($lat_long_combined) - 1]);
$map_string .= '&markers=color:red%7Clabel:F%7C' . $LatLng_finish . '&markers=color:green%7Clabel:S%7C' . $LatLng_start;
<?php
// an example of simplifying a multiline using Line_DouglasPeucker.php
// this multiline was decoded from some JSON from ArcGIS, and is a trail in Colorado
// it's expressed here in PHP literal syntax, but more realistically you'd get something
// much like this after using json_decode() from ArcGIS, or by decoding a Leaflet feature's coordinates
$before = array(array(array(-106.92121, 39.29517), array(-106.92121, 39.29527), array(-106.92127, 39.29536), array(-106.92215, 39.29605), array(-106.92277, 39.29652), array(-106.92344, 39.29691), array(-106.92408, 39.29725), array(-106.92463, 39.29748), array(-106.92543, 39.29775), array(-106.92623, 39.29801)), array(array(-106.93027, 39.29995), array(-106.93004, 39.29975), array(-106.92957, 39.29941), array(-106.92902, 39.29909), array(-106.92824, 39.29884), array(-106.92804, 39.29875), array(-106.92784, 39.29859), array(-106.92766, 39.29849), array(-106.92645, 39.29808), array(-106.92623, 39.29801)), array(array(-106.92623, 39.29801), array(-106.92601, 39.29842), array(-106.92591, 39.29845), array(-106.92562, 39.29847), array(-106.92534, 39.29849), array(-106.92518, 39.29848), array(-106.92512, 39.29845)));
// simplify to a 30-meter tolerance at this latitude (Colorado, USA)
require_once 'douglaspeuker.php';
$tolerance = 2.0E-5;
$after = simplify_RDP($before, $tolerance);
// print some results
$length_before = strlen(json_encode($before));
$length_after = strlen(json_encode($after));
print "Before: {$length} bytes as JSON\n";
print "\n";
print "After: {$length} bytes as JSON\n";