在路线中以规则的时间间隔确定中间纬度/经度

Question

我正在尝试确定一个中间纬度和列表的列表。假定从源到目的地的给定道路路线的经度。

例如 - 假设我的来源是堪萨斯城，MO＆amp;目的地是芝加哥IL，途经US-36 E和I-55 N.假设我现在要开始（没有交通延误），我怎样才能在这条路线上以1小时的间隔找到所有纬度/经度的列表？

Answer 1

一种选择是假设一个恒定的旅行率并使用第三方库的GetPointsAtDistance方法epoly.js

  // parse the distance and duration out of the response from the DirectionsService
  var duration = 0; // seconds
  var distance = 0; // meters
  for (var i = 0; i < response.routes[0].legs.length; i++) {
    duration += response.routes[0].legs[i].duration.value;
    distance += response.routes[0].legs[i].distance.value;
  }
  var points = polyline.GetPointsAtDistance(distance / (duration / 60 / 60));

proof of concept fiddle

代码段

var polyline;

function initMap() {
  var directionsService = new google.maps.DirectionsService;
  var directionsDisplay = new google.maps.DirectionsRenderer;
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 7,
    center: {
      lat: 41.85,
      lng: -87.65
    }
  });
  directionsDisplay.setMap(map);
  polyline = new google.maps.Polyline({
    path: [],
    strokeColor: '#0000FF',
    strokeWeight: 3,
    map: map
  });

  var onChangeHandler = function() {
    calculateAndDisplayRoute(directionsService, directionsDisplay, map);
  };
  document.getElementById('btn').addEventListener('click', onChangeHandler);
  calculateAndDisplayRoute(directionsService, directionsDisplay, map);
}
google.maps.event.addDomListener(window, 'load', initMap);

function calculateAndDisplayRoute(directionsService, directionsDisplay, map) {
  directionsService.route({
    origin: document.getElementById('start').value,
    destination: document.getElementById('end').value,
    travelMode: 'DRIVING'
  }, function(response, status) {
    if (status === 'OK') {
      // directionsDisplay.setDirections(response);
      renderDirections(response, map);
      var duration = 0; // seconds
      var distance = 0; // meters
      for (var i = 0; i < response.routes[0].legs.length; i++) {
        duration += response.routes[0].legs[i].duration.value;
        distance += response.routes[0].legs[i].distance.value;
      }
      document.getElementById('info').innerHTML = "total distance=" + (distance / 1000).toFixed(2) + " km<br>total duration=" + (duration / 60 / 60).toFixed(2) + " hours";
      var points = polyline.GetPointsAtDistance(distance / (duration / 60 / 60));
      // verify the result
      var request = {
        waypoints: [],
        travelMode: 'DRIVING'
      };
      for (var i = 0; i < points.length; i++) {
        var marker = new google.maps.Marker({
          map: map,
          position: points[i],
          title: "" + i
        });
        if (i == 0) {
          request.origin = marker.getPosition();
        } else if ((i > 0) && (i < (points.length - 1))) {
          request.waypoints.push({
            location: marker.getPosition(),
            stopover: true
          });
        } else {
          request.destination = marker.getPosition();
        }
      }
      directionsService.route(request, function(response, status) {
        if (status === 'OK') {
          directionsDisplay.setDirections(response);
          directionsDisplay.setPanel(document.getElementById('dirPanel'));
        } else {
          window.alert('Directions request failed due to ' + status);
        }
      });
    }
  });
}

function renderDirections(response, map) {
    // directionsDisplay.setDirections(response);
    var bounds = new google.maps.LatLngBounds();

    var legs = response.routes[0].legs;
    for (i = 0; i < legs.length; i++) {
      var steps = legs[i].steps;
      for (j = 0; j < steps.length; j++) {
        var nextSegment = steps[j].path;
        for (k = 0; k < nextSegment.length; k++) {
          polyline.getPath().push(nextSegment[k]);
          bounds.extend(nextSegment[k]);
        }
      }
    }
    // polyline.setMap(map);
  }
  // 
  /*********************************************************************\
   *                                                                     *
   * epolys.js                                          by Mike Williams *
   * updated to API v3                                  by Larry Ross    *
   *                                                                     *
   * A Google Maps API Extension                                         *
   *                                                                     *
   * Adds various Methods to google.maps.Polygon and google.maps.Polyline *
   */
  // === A method which returns an array of GLatLngs of points a given interval along the path ===
google.maps.Polyline.prototype.GetPointsAtDistance = function(metres) {
  var next = metres;
  var points = [];
  // some awkward special cases
  if (metres <= 0) return points;
  var dist = 0;
  var olddist = 0;
  for (var i = 1;
    (i < this.getPath().getLength()); i++) {
    olddist = dist;
    dist += google.maps.geometry.spherical.computeDistanceBetween(this.getPath().getAt(i), this.getPath().getAt(i - 1));
    while (dist > next) {
      var p1 = this.getPath().getAt(i - 1);
      var p2 = this.getPath().getAt(i);
      var m = (next - olddist) / (dist - olddist);
      points.push(new google.maps.LatLng(p1.lat() + (p2.lat() - p1.lat()) * m, p1.lng() + (p2.lng() - p1.lng()) * m));
      next += metres;
    }
  }
  return points;
}

html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}
#map {
  height: 100%;
}
#floating-panel {
  position: absolute;
  top: 50px;
  left: 25%;
  z-index: 5;
  background-color: #fff;
  padding: 5px;
  border: 1px solid #999;
  text-align: center;
  font-family: 'Roboto', 'sans-serif';
  line-height: 30px;
  padding-left: 10px;
}

<script src="https://maps.googleapis.com/maps/api/js?libraries=geometry"></script>
<div id="info"></div>
<div id="floating-panel">
  <b>Start: </b>
  <!-- via via US-36 E and I-55 N -->
  <input id="start" value="Kansas City, MO" />
  <br><b>End: </b>
  <input id="end" value="Chicago IL" />
  <br>
  <input id="btn" value="calculate" type="button" />
</div>
<div id="map"></div>
<div id="dirPanel"></div>