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How Google Elevation works and how to create a simple C# App?
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The article's main focus is , to create a C# console application using Google's Elevation API.
For more detailed information about this topic, use the attached links.
For more detailed information about this topic, use the attached links.
What is Google Elevation ?
Elevation is the height above or below a fixed reference point. The elevation is the referring to points on the Earth's surface.
We also use the following two terms:
- altitude: points above the surface
- depth: points below the surface
For example:
1. Simple elevation (one pair of coordinate - lat/lng)
If you search (https://maps.googleapis.com/maps/api/elevation/json?locations=47.18998999999999,23.061813&key=YOUR_API_KEY), for a specific coordinate (47.18998999999999, 23.061813) in Google Maps, you will get the following elevation result from JSON :
elevation: 254.4218444824219
To test the Elevation without API KEY, there is an example on Google: https://developers.google.com/maps/documentation/javascript/examples/elevation-simple
For C# Elevation sample, check the Elevation(string latitudeE, string longitudeE) function.
2. Multiple elevations (multiple pairs of coordinates - lat/lng)
You can also request multiple elevation results, just by adding multiple pair of coordinates and separated by the PIPE character "|". If you request https://maps.googleapis.com/maps/api/elevation/json?locations=47.18998999999999,23.061813|47.16998999999999,23.061813&key=YOUR_API_KEY , you will get the following elevation results:
//the elevation result for the first pair of coordinates
elevation: 254.4218444824219
lat: 47.18998999999999
lng: 23.061813
//the elevation result for the second pair of coordinates
elevation: 294.3569030761719
lat: 47.16998999999999
lng: 23.061813
For C# MultipleElevation sample, check the MultipleElevation(string multiplecoords) function. (It asks the user for coordinates, until the input values are empty - when the Enter key is pressed for both of the coordinates - lat/lng)
3. Path elevations (multiple pairs of coordinates - lat/lng and number of samples)
Another great feature is that you can requests elevation data along a straight line (path). For example starting from point A to point B, specifying the number of samples.
You can ask for example 3 samples:
- 2x Endpoints
- 1x Half-point
If you search for: https://maps.googleapis.com/maps/api/elevation/json?path=47.18998999999999,23.061813|47.16998999999999,23.0618131&samples=3&key=YOUR_API_KEY, you will get the following from the JSon results:
//sample 1 - Endpoint
elevation 254.4218444824219
lat 47.18998999999999
lng 23.061813
//sample 2 - Half-point
elevation 288.4825134277344
lat 47.17998999999999
lng 23.06181305000942
//sample 3 - Endpoint
elevation 294.3571472167969
lat 47.16998999999999
lng 23.0618131
For C# PathElevation sample, check the PathElevation(string multiplecoords, string nrofsamples) function. (It asks the user for coordinates until the input values are empty - when Enter key is pressed for both of the coordinates - lat/lng, after that it asks for the number of samples)
* More details about how Elevation works and how we use it, you can find in the following links:
C# Source Code sample:
The following source code is written in C# Console Application (Framework 4.5). To save space, I created a single project for Simple Elevation, Multiple Elevations, Path Elevations and a class for deserializing the JSON.
To run it, you will need the following:
-create a new API Key
-enable Maps Javascript API
-enable Maps Elevation API
-enable GeoLocation API
-enable GeoCoding API
-Visual Studio
Tip: don't forget to enable billing information in Google for the API and attach to the project
In this article I will not cover, how to enable API Keys on Google, but you can find more information on their site:
https://developers.google.com/maps/documentation/javascript/get-api-key
Create a new Console application project and after that, from NuGet, install JSon.Net (Newtonsoft.Json):
- Step 1 - File->New-> Project (I used .Net Framework 4.5)
- Step 2 - Install from Nuget Json.Net:
- Step 3 - Create a New class in the project (I named it ElevResult.cs), this will be used for deserializing the JSON request.
This is the final view of my project:
The source code for ElevResult.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Elevation_Art
{
public class GoogleElevCodeResponse
{
public string status { get; set; }
public resultsElev[] results { get; set; }
}
public class resultsElev
{
public string elevation { get; set; }
public locationElev location { get; set; }
public string resolution { get; set; }
}
public class locationElev
{
public string lat { get; set; }
public string lng { get; set; }
}
}
The source code for Program.cs:
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;
namespace Elevation_Art
{
class Program
{
const string apiKey = "YOUR_API_KEY"; //!!!!paste your API KEY HERE!!!!
static string baseUrlEL = "https://maps.googleapis.com/maps/api/elevation/json?locations="; // part of the URL for Elevation
static string baseUrlELP = "https://maps.googleapis.com/maps/api/elevation/json?path="; // part of the URL for Elevation
static string plusUrl = "&key=" + apiKey + "&sensor=false"; // part2 of the URL
static public int DisplayMenu() // I add a menu for selecting between 1 - Elevation / 2 - Elevation with Multiple Coordinates / 3 - PathElevation with Multiple Coordinates / 4 - Exit
{
Console.WriteLine();
Console.WriteLine("ELEVATION TUTORIAL (Select and hit Enter):");
Console.WriteLine();
Console.WriteLine("1. Elevation"); // 1 Elevation with single pair of coordinates
Console.WriteLine("2. Elevation with Multiple Coordinates"); // 2 Multiple Elevation results, from multiple pair of coordinates
Console.WriteLine("3. PathElevation with Multiple Coordinates"); // 3 Multiple Elevation (PathElevation) results, from multiple pair of coordinates and samples
Console.WriteLine("4. Exit"); // 4 Exit
Console.WriteLine();
var result = Console.ReadLine(); //waiting for an integer input for the menu; value can between 1-3
return Convert.ToInt32(result); //converting result to an integer for the menu
}
static void Main(string[] args)
{
int menuInput = 0;
do // do-while statement for the menu, it loops until the input is 3 (Exit)
{
Console.ForegroundColor = ConsoleColor.Green; // changing color for the console to green
menuInput = DisplayMenu(); //getting the result of the input for the menu
Console.ForegroundColor = ConsoleColor.Gray; // changing to default color
switch (menuInput.ToString()) //switch statement for checking if input is 1 - 3, 4 - Exit
{
case "1": //if the input for menu is 1, then call the Elevation function
Console.WriteLine("===== ELEVATION =====");
Console.WriteLine("Enter a Latitude: ");
string latitudeE = Console.ReadLine();
Console.WriteLine("Enter a Longitude: ");
string longitudeE = Console.ReadLine();
Console.WriteLine("-------------------------------------");
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("RESULT: " + Elevation(latitudeE, longitudeE) + " meters");
Console.ForegroundColor = ConsoleColor.Gray;
break;
case "2": //if the input for menu is 2, then call the MultipleElevation function
Console.WriteLine("===== MULTIPLE ELEVATION =====");
string latitudeEM = string.Empty;
string longitudeEM = string.Empty;
StringBuilder sb = new StringBuilder();
do
{
Console.WriteLine("Enter a Latitude: ");
latitudeEM = Console.ReadLine();
Console.WriteLine("Enter a Longitude: ");
longitudeEM = Console.ReadLine();
sb.Append(latitudeEM + "," + longitudeEM + "|"); //format LAT/LNG coordinates and append to StringBuilder
} while ((latitudeEM.ToString() != "") || (longitudeEM.ToString() != "")); //request input from user, util LAT and LNG is empty char (Enter)
Console.WriteLine("-------------------------------------");
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("RESULT: " + MultipleElevation(sb.ToString().Replace("|,|", "")) + " meters"); //call the function MultipleElevation
Console.ForegroundColor = ConsoleColor.Gray;
break;
case "3": //if the input for menu is 3, then call the PathElevation function
Console.WriteLine("===== PATH ELEVATION =====");
string latitudeEMP = string.Empty;
string longitudeEMP = string.Empty;
StringBuilder sbp = new StringBuilder();
do
{
Console.WriteLine("Enter a Latitude: ");
latitudeEMP = Console.ReadLine();
Console.WriteLine("Enter a Longitude: ");
longitudeEMP = Console.ReadLine();
sbp.Append(latitudeEMP + "," + longitudeEMP + "|"); //format LAT/LNG coordinates and append to StringBuilder
} while ((latitudeEMP.ToString() != "") || (longitudeEMP.ToString() != "")); //request input from user, util LAT and LNG is empty char (Enter)
Console.WriteLine("Enter the number of samples: ");
string nrOfSamples = Console.ReadLine();
Console.WriteLine("-------------------------------------");
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("RESULT: " + PathElevation(sbp.ToString().Replace("|,|", ""),nrOfSamples) + " meters"); //call the function PathElevation
Console.ForegroundColor = ConsoleColor.Gray;
break;
}
} while (menuInput != 4);
}
private static string Elevation(string latitudeE, string longitudeE)
{
var json = new WebClient().DownloadString(baseUrlEL + latitudeE.Replace(" ", "") + ","
+ longitudeE.Replace(" ", "") + plusUrl);//concatenate URL with the input lat/lng and downloads the requested resource
GoogleElevCodeResponse jsonResult = JsonConvert.DeserializeObject<GoogleElevCodeResponse>(json); //deserializing the result to GoogleElevCodeResponse
string status = jsonResult.status; // get status
string geoElevation = String.Empty;
geoElevation += Environment.NewLine;
if (status == "OK") //check if status is OK
{
for (int i = 0; i < jsonResult.results.Length; i++) //loop throught the result for addresses
{
geoElevation += "Lat/Lng[" + i + "]: " + jsonResult.results[i].location.lat + " / " + jsonResult.results[i].location.lng + " Elevation[" + i + "]: " + jsonResult.results[i].elevation + Environment.NewLine; //append the result elevations and coords to every new line
}
return geoElevation; //return result
}
else
{
return status; //return status / error if not OK
}
}
private static string MultipleElevation(string multiplecoords)
{
var json = new WebClient().DownloadString(baseUrlEL + multiplecoords + plusUrl);//concatenate URL with the input lat/lng and downloads the requested resource
GoogleElevCodeResponse jsonResult = JsonConvert.DeserializeObject<GoogleElevCodeResponse>(json); //deserializing the result to GoogleElevCodeResponse
string status = jsonResult.status; // get status
string geoElevation = String.Empty;
geoElevation += Environment.NewLine;
if (status == "OK") //check if status is OK
{
for (int i = 0; i < jsonResult.results.Length; i++) //loop throught the result for addresses
{
geoElevation += "Lat/Lng[" + i + "]: " + jsonResult.results[i].location.lat + " / " + jsonResult.results[i].location.lng + " Elevation[" + i + "]: " + jsonResult.results[i].elevation + Environment.NewLine; //append the result elevations and coords to every new line
}
return geoElevation; //return result
}
else
{
return status; //return status / error if not OK
}
}
private static string PathElevation(string multiplecoords, string nrofsamples)
{
var json = new WebClient().DownloadString(baseUrlELP + multiplecoords+"&samples="+nrofsamples+ plusUrl);//concatenate URL with the input lat/lng and downloads the requested resource
GoogleElevCodeResponse jsonResult = JsonConvert.DeserializeObject<GoogleElevCodeResponse>(json); //deserializing the result to GoogleElevCodeResponse
string status = jsonResult.status; // get status
string geoElevation = String.Empty;
geoElevation += Environment.NewLine;
if (status == "OK") //check if status is OK
{
for (int i = 0; i < jsonResult.results.Length; i++) //loop throught the result for addresses
{
geoElevation += "Lat/Lng[" + i + "]: " + jsonResult.results[i].location.lat + " / " + jsonResult.results[i].location.lng + " Elevation[" + i + "]: " + jsonResult.results[i].elevation + Environment.NewLine; //append the result elevations and coords to every new line
}
return geoElevation; //return result
}
else
{
return status; //return status / error if not OK
}
}
}
}
Some screenshots of the working app
The menu: (Waiting for user input 1-4)
1. Simple Elevation (for the following coords: 47.18998999999999, 23.061813, check result in red):
2. Multiple Elevations (for the following coords: 47.18998999999999,23.061813|47.16998999999999,23.061813, check results in red):
3. PathElevations (for the following coords: 47.18998999999999,23.061813|47.16998999999999,23.061813 and with the number of samples: 3, check results in red):
4. for Exit
Source Code:
Entire Project:
I wish you happy coding!
Molnár István
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