使用带有标记的谷歌街景视图，如何将 POV 指向标记？

Question

我有一个简单的街景视图，可以向我显示给定地址的街景视图：

var geocoder = new google.maps.Geocoder();
var address = "344 Laguna Dr, Milpitas, CA  95035";
geocoder.geocode( { 'address': address}, 
    function(results, status) {
        //alert (results);
    if (status == google.maps.GeocoderStatus.OK) {
        //alert(results[0].geometry.location);
        myStreetView = new google.maps.StreetViewPanorama(document.getElementById("map_canvas"));
        myStreetView.setPosition(results[0].geometry.location);
        var marker = new google.maps.Marker({
            position: results[0].geometry.location, 
            map: myStreetView, 
            title:address
        });
        //alert ("yay");
    } else {
        alert("Geocode was not successful for the following reason: " + status);
    }
});

如您所见，我在街景视图上添加了地址标记。我的问题是，街景指向北，而标记指向南。对于非特定地址，如何指定街景视图应指向该地址的标记，而不是默认指向北？

Answer 1

原因是街景 POV 默认情况下是拍摄图像时卡车所面向的方向（见图）。您需要获取卡车的位置和房屋的位置，并计算从第一个位置到第二个位置的“航向”，然后将您的街景位置设置为具有刚刚计算的航向的卡车的位置：

// adrloc=target address
// svwloc=street-view truck location
svwService.getPanoramaByLocation(adrloc,svwdst,function(dta,sts) {
    if(sts==google.maps.StreetViewStatus.OK) {
        var svwloc=dta.location.latLng;
        var svwhdg=google.maps.geometry.spherical.computeHeading(svwloc,adrloc);
        var svwmap=avwMap.getStreetView();
        svwmap.setPosition(svwloc);
        svwmap.setPov({ heading: svwhdg, pitch: 0 });
        svwMarker=new google.maps.Marker({ map:svwmap, position: adrloc });
        svwmap.setVisible(true);
        }
    else {
        ...
        }

使用街景视图的另一个技巧/陷阱是，您需要通过不断增加距离重复调用 getPanoramaByLocation 来获取距离您的地址位置最近的街景视图，直到成功或达到某个最大值距离。我使用这段代码解决了这个问题：

var SVW_MAX=100; // maximum street-view distance in meters
var SVW_INC=10;  // increment street-view distance in meters
var svwService=new google.maps.StreetViewService(); // street view service
var svwMarker=null; // street view marker

// NOTE: avwMap is the aerial view map, code not shown
...
resolveStreetView(avwMap.getCenter(),SVW_INC); 
...

var resolveStreetView=function(adrloc,svwdst) {
    svwService.getPanoramaByLocation(adrloc,svwdst,function(dta,sts) {
        if(sts==google.maps.StreetViewStatus.OK) {
            var svwloc=dta.location.latLng;
            var svwhdg=google.maps.geometry.spherical.computeHeading(svwloc,adrloc);
            var svwmap=avwMap.getStreetView();
            svwmap.setPosition(svwloc);
            svwmap.setPov({ heading: svwhdg, pitch: 0 });
            svwMarker=new google.maps.Marker({ map:svwmap, position: adrloc });
            svwmap.setVisible(true);
            }
        else if(svwdst<SVW_MAX) {
            resolveStreetView(adrloc,svwdst+SVW_INC);
            }
        });
    }

Answer 2

请查看此示例。即使它是 V2，您也可以重用该代码。基本上，您需要调用computeAngle(markerLatLng, streetviewPanoLatLng)，并将街景全景的偏航设置为返回值。

function computeAngle(endLatLng, startLatLng) {
  var DEGREE_PER_RADIAN = 57.2957795;
  var RADIAN_PER_DEGREE = 0.017453;

  var dlat = endLatLng.lat() - startLatLng.lat();
  var dlng = endLatLng.lng() - startLatLng.lng();
  // We multiply dlng with cos(endLat), since the two points are very closeby,
  // so we assume their cos values are approximately equal.
  var yaw = Math.atan2(dlng * Math.cos(endLatLng.lat() * RADIAN_PER_DEGREE), dlat)
         * DEGREE_PER_RADIAN;
  return wrapAngle(yaw);
}

function wrapAngle(angle) {
  if (angle >= 360) {
    angle -= 360;
  } else if (angle < 0) {
    angle += 360;
  }
  return angle;
 }

Answer 3

基于您的代码的简单示例：

1. 获取要查看的位置（使用地理编码器）
2. 获取 StreetViewPanorama（一旦其状态发生更改，就使用 getLocation() 方法，替代方案是使用 getPosition() 方法的结果）。
3. 使用几何库的computeHeading方法来计算从相机到地址。
4. 使用 setPov() 方法设置该标题。
5. 延迟，以便标记到达正确的位置（删除此标记会使标记位于左上角）。如果不使用标记则不需要。

function geocodeAddress() {
  var address = "344 Laguna Dr, Milpitas, CA  95035";
  geocoder.geocode({
    'address': address
  }, function(results, status) {
    //alert (results);
    if (status == google.maps.GeocoderStatus.OK) {
      //alert(results[0].geometry.location);
      myStreetView = new google.maps.StreetViewPanorama(document.getElementById("map_canvas"));
      myStreetView.setPosition(results[0].geometry.location);
      google.maps.event.addListenerOnce(myStreetView, 'status_changed', function() {
        var heading = google.maps.geometry.spherical.computeHeading(myStreetView.getLocation().latLng, results[0].geometry.location);
        myStreetView.setPov({
          heading: heading,
          pitch: 0
        });
        setTimeout(function() {
          marker = new google.maps.Marker({
            position: results[0].geometry.location,
            map: myStreetView,
            title: address
          });
          if (marker && marker.setMap) marker.setMap(myStreetView);
        }, 500);
      });

    } else {
      alert("Geocode was not successful for the following reason: " + status);
    }
  });
  google.maps.event.addDomListener(document.getElementById('geoBtn'), 'click', geocodeAddress);
}

工作小提琴

工作代码片段：

var geocoder = new google.maps.Geocoder();
var myStreetView = null;
var marker = null;

function geocodeAddress() {
  // var address = "344 Laguna Dr, Milpitas, CA  95035";
  var address = document.getElementById('address').value;
  geocoder.geocode({
    'address': address
  }, function(results, status) {
    //alert (results);
    if (status == google.maps.GeocoderStatus.OK) {
      //alert(results[0].geometry.location);
      myStreetView = new google.maps.StreetViewPanorama(document.getElementById("map_canvas"));
      myStreetView.setPosition(results[0].geometry.location);
      google.maps.event.addListenerOnce(myStreetView, 'status_changed', function() {
        var heading = google.maps.geometry.spherical.computeHeading(myStreetView.getLocation().latLng, results[0].geometry.location);
        myStreetView.setPov({
          heading: heading,
          pitch: 0
        });
        setTimeout(function() {
          marker = new google.maps.Marker({
            position: results[0].geometry.location,
            map: myStreetView,
            title: address
          });
          if (marker && marker.setMap) marker.setMap(myStreetView);
        }, 500);
      });

    } else {
      alert("Geocode was not successful for the following reason: " + status);
    }
  });
  google.maps.event.addDomListener(document.getElementById('geoBtn'), 'click', geocodeAddress);
}
google.maps.event.addDomListener(window, 'load', geocodeAddress);

html,
body,
#map_canvas {
  height: 100%;
  width: 100%;
}

<script src="http://maps.google.com/maps/api/js?libraries=geometry&key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk"></script>
<input id="address" type="text" value="344 Laguna Dr, Milpitas, CA  95035" />
<input id="geoBtn" type="button" value="Go" />
<div id="map_canvas"></div>