在Android中通过经度和纬度获取高度
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Get altitude by longitude and latitude in Android
提问by Maksym Gontar
Is there a quick and efficient way to get altitude (elevation) by longitude and latitude on the Android platform?
在Android平台上有没有快速有效的通过经纬度获取高度（海拔）的方法？
回答by Maksym Gontar
My approach is to use USGS Elevation Query Web Service:
我的方法是使用USGS Elevation Query Web Service：
private double getAltitude(Double longitude, Double latitude) {
double result = Double.NaN;
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
String url = "http://gisdata.usgs.gov/"
+ "xmlwebservices2/elevation_service.asmx/"
+ "getElevation?X_Value=" + String.valueOf(longitude)
+ "&Y_Value=" + String.valueOf(latitude)
+ "&Elevation_Units=METERS&Source_Layer=-1&Elevation_Only=true";
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse response = httpClient.execute(httpGet, localContext);
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
int r = -1;
StringBuffer respStr = new StringBuffer();
while ((r = instream.read()) != -1)
respStr.append((char) r);
String tagOpen = "<double>";
String tagClose = "</double>";
if (respStr.indexOf(tagOpen) != -1) {
int start = respStr.indexOf(tagOpen) + tagOpen.length();
int end = respStr.indexOf(tagClose);
String value = respStr.substring(start, end);
result = Double.parseDouble(value);
}
instream.close();
}
} catch (ClientProtocolException e) {}
catch (IOException e) {}
return result;
}
And example of use (right in HelloMapViewclass):
和使用示例（就在HelloMapView类中）：
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
linearLayout = (LinearLayout) findViewById(R.id.zoomview);
mapView = (MapView) findViewById(R.id.mapview);
mZoom = (ZoomControls) mapView.getZoomControls();
linearLayout.addView(mZoom);
mapView.setOnTouchListener(new OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == 1) {
final GeoPoint p = mapView.getProjection().fromPixels(
(int) event.getX(), (int) event.getY());
final StringBuilder msg = new StringBuilder();
new Thread(new Runnable() {
public void run() {
final double lon = p.getLongitudeE6() / 1E6;
final double lat = p.getLatitudeE6() / 1E6;
final double alt = getAltitude(lon, lat);
msg.append("Lon: ");
msg.append(lon);
msg.append(" Lat: ");
msg.append(lat);
msg.append(" Alt: ");
msg.append(alt);
}
}).run();
Toast.makeText(getBaseContext(), msg, Toast.LENGTH_SHORT)
.show();
}
return false;
}
});
}
回答by dhael
You can also use the Google Elevation API. The online documentation for it is located at: https://developers.google.com/maps/documentation/elevation/
您还可以使用 Google Elevation API。它的在线文档位于：https: //developers.google.com/maps/documentation/elevation/
Please note the following from the above API page:
请注意上述 API 页面中的以下内容：
Usage Limits: Use of the Google Geocoding API is subject to a query limit of 2,500 geolocation requests per day. (User of Google Maps API Premier may perform up to 100,000 requests per day.) This limit is enforced to prevent abuse and/or repurposing of the Geocoding API, and this limit may be changed in the future without notice. Additionally, we enforce a request rate limit to prevent abuse of the service. If you exceed the 24-hour limit or otherwise abuse the service, the Geocoding API may stop working for you temporarily. If you continue to exceed this limit, your access to the Geocoding API may be blocked. Note: the Geocoding API may only be used in conjunction with a Google map; geocoding results without displaying them on a map is prohibited. For complete details on allowed usage, consult the Maps API Terms of Service License Restrictions.
使用限制：使用 Google Geocoding API 的查询限制为每天 2,500 个地理定位请求。（Google Maps API Premier 的用户每天最多可以执行 100,000 个请求。）强制执行此限制是为了防止滥用和/或重新利用 Geocoding API，并且此限制将来可能会更改，恕不另行通知。此外，我们强制执行请求速率限制以防止滥用服务。如果您超过 24 小时限制或以其他方式滥用服务，地理编码 API 可能会暂时停止为您工作。如果您继续超过此限制，您对地理编码 API 的访问可能会被阻止。注意：Geocoding API 只能与谷歌地图结合使用；禁止地理编码结果而不在地图上显示。有关允许使用的完整详细信息，
Altering Max Gontar'scode above for the Google API gives the following, with the returned elevation given in feet:
更改上面针对 Google API 的Max Gontar代码给出了以下内容，返回的高度以英尺为单位：
private double getElevationFromGoogleMaps(double longitude, double latitude) {
double result = Double.NaN;
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
String url = "http://maps.googleapis.com/maps/api/elevation/"
+ "xml?locations=" + String.valueOf(latitude)
+ "," + String.valueOf(longitude)
+ "&sensor=true";
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse response = httpClient.execute(httpGet, localContext);
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
int r = -1;
StringBuffer respStr = new StringBuffer();
while ((r = instream.read()) != -1)
respStr.append((char) r);
String tagOpen = "<elevation>";
String tagClose = "</elevation>";
if (respStr.indexOf(tagOpen) != -1) {
int start = respStr.indexOf(tagOpen) + tagOpen.length();
int end = respStr.indexOf(tagClose);
String value = respStr.substring(start, end);
result = (double)(Double.parseDouble(value)*3.2808399); // convert from meters to feet
}
instream.close();
}
} catch (ClientProtocolException e) {}
catch (IOException e) {}
return result;
}
回答by Always Lucky
It's important to first differentiate altitude from elevation.
首先区分海拔高度很重要。
Altitude is the distance from a point down to the local surface; whether that be land or water. This measurement is mainly used for aviation.
高度是从一个点向下到当地表面的距离；无论是陆地还是水域。这种测量主要用于航空。
Altitude can be obtained by using the Location.getAltitude()function.
可以使用Location.getAltitude()函数获取高度。
Elevation is the distance from the local surface to the sea level; much more often used, and often mistakenly referred to as altitude.
海拔是当地表面到海平面的距离；更经常使用，并且经常被错误地称为高度。
With that said, for the US, USGS has provided a newer HTTP POST and GET queriesthat can return XML or JSON values for elevation in either feet or meters. For worldwide elevation, you could use the Google Elevation API.
话虽如此，对于美国，USGS 提供了更新的 HTTP POST 和 GET 查询，可以返回 XML 或 JSON 值，以英尺或米为单位的高程。对于全球海拔，您可以使用Google Elevation API。
回答by Always Lucky
If u are using android device which has GPS Recever then there is a method getAltitude()by using that u can get the altitude by elevation.
如果您使用的是带有 GPS 接收器的 android 设备，那么有一种方法getAltitude()通过使用您可以通过海拔获取高度。
回答by Frank Mu?oz
Google maps have the altitude, what you need is this code
谷歌地图有海拔高度，你需要的是这个代码
altitude="";
var init = function() {
var elevator = new google.maps.ElevationService;
map.on('mousemove', function(event) {
getLocationElevation(event.latlng, elevator);
document.getElementsByClassName("altitudeClass")[0].innerHTML = "Altitude: "+ getAltitude();
//console.debug(getAltitude());
});
}
var getLocationElevation = function (location, elevator){
// Initiate the location request
elevator.getElevationForLocations({
'locations': [location]
}, function(results, status) {
if (status === google.maps.ElevationStatus.OK) {
// Retrieve the first result
if (results[0]) {
// Open the infowindow indicating the elevation at the clicked position.
setAltitude(parseFloat(results[0].elevation).toFixed(2));
} else {
setAltitude('No results found');
}
} else {
setAltitude('Elevation service failed due to: ' + status);
}
});
}
function setAltitude(a){
altitude = a;
}
function getAltitude(){
return altitude;
}
回答by Gaploid
Try this one that I`v built: https://algorithmia.com/algorithms/Gaploid/Elevation
试试我构建的这个：https://algorithmia.com/algorithms/Gaploid/Elevation
here is example for Java:
这是 Java 的示例：
import com.algorithmia.*;
import com.algorithmia.algo.*;
String input = "{\"lat\": \"50.2111\", \"lon\": \"18.1233\"}";
AlgorithmiaClient client = Algorithmia.client("YOUR_API_KEY");
Algorithm algo = client.algo("algo://Gaploid/Elevation/0.3.0");
AlgoResponse result = algo.pipeJson(input);
System.out.println(result.asJson());
回答by M66B
The idea to use the Google Elevation API is good, but parsing XML using string functions is not. Also, HttpClient is deprecated now, as using insecure connections.
使用 Google Elevation API 的想法很好，但使用字符串函数解析 XML 则不然。此外，现在不推荐使用 HttpClient，因为它使用不安全的连接。
See here for a better solution: https://github.com/M66B/BackPackTrackII/blob/master/app/src/main/java/eu/faircode/backpacktrack2/GoogleElevationApi.java
在这里查看更好的解决方案：https: //github.com/M66B/BackPackTrackII/blob/master/app/src/main/java/eu/faircode/backpacktrack2/GoogleElevationApi.java
