/// <summary>
/// Bounding Polygon
/// Get all the hashString covered by the polygon in numberOfChars
/// </summary>
/// <param name="polygon">array of coordinates describes the polygon</param>
/// <param name="numberOfChars"></param>
/// <returns>array of hash string</returns>
public static string[] Bpolygon(Coordinates[] polygon, int numberOfChars = 9)
{
var hashList = new List <string>();
// Get all bounding boxes that are possible be covered by polygon
Coordinates max = new Coordinates {
Lat = -90, Lon = -180
};
Coordinates min = new Coordinates {
Lat = 90, Lon = 180
};
foreach (Coordinates c in polygon)
{
max.Lat = Math.Max(max.Lat, c.Lat);
max.Lon = Math.Max(max.Lon, c.Lon);
min.Lat = Math.Min(min.Lat, c.Lat);
min.Lon = Math.Min(min.Lon, c.Lon);
}
string[] bboxHash = GeoHash.Bboxes(min.Lat, min.Lon, max.Lat, max.Lon, numberOfChars);
foreach (string hash in bboxHash)
{
BoundingBox box = GeoHash.DecodeBbox(hash);
if (BoxOverlapPolygon(box, polygon))
{
hashList.Add(hash);
}
}
return(hashList.ToArray());
}
/// <summary>
/// Bounding Box Coordinates
/// Get all coordinates covered by the box in numberOfChars
/// </summary>
/// <param name="minLat"></param>
/// <param name="minLon"></param>
/// <param name="maxLat"></param>
/// <param name="maxLon"></param>
/// <param name="numberOfChars"></param>
/// <returns>all coordinates covered by the box in numberOfChars</returns>
public Coordinates[] BboxCoordinates(double minLat, double minLon, double maxLat, double maxLon, int numberOfChars = 9)
{
var coorList = new List <Coordinates>();
string[] hashList = GeoHash.Bboxes(minLat, minLon, maxLat, maxLat, numberOfChars);
foreach (string hash in hashList)
{
// TODO: search all level or search current level only?
Coordinates[] coors = GetCoordinates(hash);
BoundingBox box = GeoHash.DecodeBbox(hash);
if (BoxInBoxRange(box, minLat, minLon, maxLat, maxLon))
{
// All covered by box
coorList.AddRange(coors);
}
else
{
// Not all covered by box
foreach (Coordinates c in coors)
{
if (CoordinateInBoxRange(c, minLat, minLon, maxLat, maxLon))
{
coorList.Add(c);
}
}
}
}
return(coorList.ToArray());
}
/// <summary>
/// Find the length of the shortest side of a box
/// </summary>
/// <param name="hash"></param>
/// <returns>length in meter</returns>
public static double FindMinSideLength(string hash)
{
BoundingBox box = GeoHash.DecodeBbox(hash);
double west = Measure(box.Minimum.Lat, box.Minimum.Lon, box.Maximum.Lat, box.Minimum.Lon);
double east = Measure(box.Minimum.Lat, box.Maximum.Lon, box.Maximum.Lat, box.Maximum.Lon);
double south = Measure(box.Minimum.Lat, box.Minimum.Lon, box.Minimum.Lat, box.Maximum.Lon);
double north = Measure(box.Maximum.Lat, box.Maximum.Lon, box.Maximum.Lat, box.Minimum.Lon);
return(Math.Min(Math.Min(west, east), Math.Min(north, south)));
}
/// <summary>
/// Get all bounding boxes covered by polygon in numberOfChars
/// </summary>
/// <param name="polygon">array of coordinates describes the polygon</param>
/// <param name="numberOfChars"></param>
/// <returns>array of hash string</returns>
public static BoundingBox[] BpolygonBoxes(Coordinates[] polygon, int numberOfChars = 9)
{
var boxList = new List <BoundingBox>();
string[] hashList = Bpolygon(polygon, numberOfChars);
foreach (string hash in hashList)
{
boxList.Add(GeoHash.DecodeBbox(hash));
}
return(boxList.ToArray());
}
/// <summary>
/// Get all bounding boxes covered by box
/// </summary>
/// <param name="minLat"></param>
/// <param name="minLon"></param>
/// <param name="maxLat"></param>
/// <param name="maxLon"></param>
/// <param name="numberOfChars"></param>
/// <returns></returns>
public static BoundingBox[] BboxBoxes(double minLat, double minLon, double maxLat, double maxLon, int numberOfChars = 9)
{
var boxList = new List <BoundingBox>();
string[] hashList = GeoHash.Bboxes(minLat, minLon, maxLat, maxLon, numberOfChars);
foreach (string hash in hashList)
{
boxList.Add(GeoHash.DecodeBbox(hash));
}
return(boxList.ToArray());
}
/// <summary>
/// Get all bounding boxes that covers the circle
/// </summary>
/// <param name="latitude">latitude of center point</param>
/// <param name="longitude">longitude of center point</param>
/// <param name="radius">radius in meters</param>
/// <param name="numberOfChars">number of characters of hash string</param>
/// <returns>bounding box object array</returns>
public static BoundingBox[] BcircleBoxes(double latitude, double longitude, double radius, int numberOfChars = 9)
{
var boxList = new List <BoundingBox>();
string[] hashList = Bcircle(latitude, longitude, radius, numberOfChars);
foreach (string hash in hashList)
{
boxList.Add(GeoHash.DecodeBbox(hash));
}
return(boxList.ToArray());
}
public static void BoundingCircleTest()
{
Coordinates c = new Coordinates {
Lat = mLat, Lon = mLon
};
Console.WriteLine("point latitude " + c.Lat + ", longitude " + c.Lon);
var encoded = GeoHash.Encode(c.Lat, c.Lon, mLevel);
Console.WriteLine("encoded = " + encoded);
var decoded = GeoHash.Decode(encoded);
var latitude = decoded.Coordinates.Lat;
var longitude = decoded.Coordinates.Lon;
Console.WriteLine("decoded box latitude " + latitude + ", longitude " + longitude);
BoundingBox box = GeoHash.DecodeBbox(encoded);
var maxLat = box.Maximum.Lat;
var minLat = box.Minimum.Lat;
var maxLon = box.Maximum.Lon;
var minLon = box.Minimum.Lon;
// Measure the box size in meters
var oneSide = DataBase.Measure(maxLat, minLon, minLat, minLon);
var anotherSide = DataBase.Measure(maxLat, maxLon, maxLat, minLon);
// Bounding circle
var watch = System.Diagnostics.Stopwatch.StartNew();
string[] hashList = DataBase.Bcircle(c.Lat, c.Lon, mRadius, mLevel);
watch.Stop();
var elapsedMs = watch.ElapsedMilliseconds;
//foreach (var h in hashList)
//{
// Console.WriteLine(h);
//}
Console.WriteLine("box size: " + oneSide + " meters * " + anotherSide + " meters");
Console.WriteLine("bounding circle radius " + mRadius + " meters, level " + mLevel);
Console.WriteLine("Get bounding circle, time elapsed: " + elapsedMs + " ms | " + hashList.Length + " results get");
string filename = "bounding circle" + c.Lat.ToString() + "-" + c.Lon.ToString() + "-" + mRadius.ToString() + "-" + mLevel.ToString();
KMLGenerator.GenerateKMLBoundingCircle(hashList, c.Lat, c.Lon, mRadius, filename);
Console.WriteLine("save as file name " + filename);
}
/// <summary>
/// Bounding Circle Coordinates
/// Get all coordinates covered by the circle in numberOfChars
/// </summary>
/// <param name="latitude">latitude of center point</param>
/// <param name="longitude">longitude of center point</param>
/// <param name="radius">radius in meters</param>
/// <param name="numberOfChars">number of characters of hash string</param>
/// <param name="limit">max number of coordinates return</param>
/// <returns>array of coordinate object</returns>
public Coordinates[] BcircleCoordinates(double latitude, double longitude, double radius, int numberOfChars = 9, int limit = 0)
{
var coorList = new List <Coordinates>();
string[] hashList = Bcircle(latitude, longitude, radius, numberOfChars);
foreach (string hash in hashList)
{
// TODO: search all level or search current level only?
Coordinates[] coors = GetCoordinates(hash);
BoundingBox box = GeoHash.DecodeBbox(hash);
if (BoxAllInCircleRange(box, latitude, longitude, radius))
{
// All covered by circle
coorList.AddRange(coors);
}
else
{
// Not all covered by circle
foreach (Coordinates c in coors)
{
if (Measure(c.Lat, c.Lon, latitude, longitude) <= radius)
{
coorList.Add(c);
}
}
}
}
if (limit == 0)
{
return(coorList.ToArray());
}
coorList.Sort((x, y) => Measure(x.Lat, x.Lon, latitude, longitude).CompareTo(Measure(y.Lat, y.Lon, latitude, longitude)));
if (coorList.Count >= limit)
{
return(coorList.GetRange(0, limit).ToArray());
}
return(coorList.ToArray());
}
/**
* Draw bounding circle
* Generate kml from a list of boxhash
*/
public static void GenerateKMLBoundingCircle(string[] hashList, double latitude, double longitude, double radius, string fileName)
{
string kmlStr = $@"<?xml version=""1.0"" encoding=""UTF-8""?>
<kml xmlns=""http://www.opengis.net/kml/2.2"" >
<Document>
<name>BoundingCircle</name>
<Style id=""yellowLineGreenPoly"">
<LineStyle>
<color> 7f00ffff </color>
<width> 4 </width>
</LineStyle>
<PolyStyle>
<color> 7f00ff00 </color>
</PolyStyle>
</Style>
<Placemark>
<styleUrl>#yellowLineGreenPoly</styleUrl>
<MultiGeometry>";
foreach (string hash in hashList)
{
kmlStr += "\n";
kmlStr += @" <LineString>
<extrude> 1 </extrude >
<tessellate> 1 </tessellate>
<altitudeMode> absolute </altitudeMode>
<coordinates> ";
var box = GeoHash.DecodeBbox(hash);
kmlStr += box.Maximum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Maximum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += box.Maximum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Minimum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += box.Minimum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Minimum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += box.Minimum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Maximum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += box.Maximum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Maximum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += @" </coordinates>
</LineString>";
}
kmlStr += "\n";
kmlStr += @" <LineString>
<extrude> 1 </extrude >
<tessellate> 1 </tessellate>
<altitudeMode> absolute </altitudeMode>
<coordinates> ";
// Draw the circle
for (double degree = 0; degree < 360; degree += 0.5)
{
var coor = DataBase.DistanceToPoint(latitude, longitude, radius, degree);
kmlStr += coor.Lon.ToString();
kmlStr += ",";
kmlStr += coor.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
//Console.WriteLine(Measure(latitude, longitude, coor.Lat, coor.Lon));
}
kmlStr += @" </coordinates>
</LineString>";
// Draw center
kmlStr += "<Point><coordinates>" +
longitude.ToString() + "," + latitude.ToString()
+ "</coordinates></Point>";
kmlStr += @"
</MultiGeometry>
</Placemark>
</Document>
</kml>";
using (StreamWriter sw = new StreamWriter(fileName + ".kml"))
{
sw.WriteLine(kmlStr);
}
}
/**
* Draw bounding boxes
* Generate kml from a list of boxhash
*/
public static void GenerateKMLBoundingBoxes(string[] hashList, Coordinates coorMin, Coordinates coorMax, string fileName)
{
string kmlStr = $@"<?xml version=""1.0"" encoding=""UTF-8""?>
<kml xmlns=""http://www.opengis.net/kml/2.2"" >
<Document>
<name>BoundingBoxes</name>
<Style id=""yellowLineGreenPoly"">
<LineStyle>
<color> 7f00ffff </color>
<width> 4 </width>
</LineStyle>
<PolyStyle>
<color> 7f00ff00 </color>
</PolyStyle>
</Style>
<Placemark>
<styleUrl>#redLineGreenPoly</styleUrl>
<MultiGeometry>";
foreach (string hash in hashList)
{
//Console.WriteLine(hash+",");
kmlStr += "\n";
kmlStr += @"
<LineString>
<extrude> 1 </extrude >
<tessellate> 1 </tessellate>
<altitudeMode> absolute </altitudeMode>
<coordinates> ";
var box = GeoHash.DecodeBbox(hash);
kmlStr += box.Maximum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Maximum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += box.Maximum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Minimum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += box.Minimum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Minimum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += box.Minimum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Maximum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += box.Maximum.Lon.ToString();
kmlStr += ",";
kmlStr += box.Maximum.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += @" </coordinates>
</LineString>";
}
// Draw bounding box
kmlStr += "\n";
kmlStr += @" <LineString>
<extrude> 1 </extrude >
<tessellate> 1 </tessellate>
<altitudeMode> absolute </altitudeMode>
<coordinates> ";
kmlStr += coorMin.Lon.ToString();
kmlStr += ",";
kmlStr += coorMin.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += coorMin.Lon.ToString();
kmlStr += ",";
kmlStr += coorMax.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += coorMax.Lon.ToString();
kmlStr += ",";
kmlStr += coorMax.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += coorMax.Lon.ToString();
kmlStr += ",";
kmlStr += coorMin.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += coorMin.Lon.ToString();
kmlStr += ",";
kmlStr += coorMin.Lat.ToString();
kmlStr += ",20";
kmlStr += "\n";
kmlStr += @" </coordinates>
</LineString>";
kmlStr += @"
</MultiGeometry>
</Placemark>
</Document>
</kml>";
using (StreamWriter sw = new StreamWriter(fileName + ".kml"))
{
sw.WriteLine(kmlStr);
}
}
/// <summary>
/// Bounding Circle
/// Get all the hashString covered by the circle in numberOfChars
/// </summary>
/// <param name="latitude">latitude of center point</param>
/// <param name="longitude">longitude of center point</param>
/// <param name="radius">radius in meters</param>
/// <param name="numberOfChars">number of characters of hash string</param>
/// <returns>hash string array</returns>
public static string[] Bcircle(double latitude, double longitude, double radius, int numberOfChars = 9)
{
var hashList = new List <string>();
string hashCenter = GeoHash.Encode(latitude, longitude, numberOfChars);
hashList.Add(hashCenter);
GeohashDecodeResult latLon = GeoHash.Decode(hashCenter);
// Find left and right end
// Find west(left) end
Coordinates leftCoor = DistanceToPoint(latitude, longitude, radius, 270);
string hashLeft = GeoHash.Encode(leftCoor.Lat, leftCoor.Lon, numberOfChars);
NGeoHash.BoundingBox boxLeft = GeoHash.DecodeBbox(hashLeft);
// Find east(right) end
Coordinates rightCoor = DistanceToPoint(latitude, longitude, radius, 90);
string hashRight = GeoHash.Encode(rightCoor.Lat, rightCoor.Lon, numberOfChars);
NGeoHash.BoundingBox boxRight = GeoHash.DecodeBbox(hashRight);
// Find steps(from left to right)
double perLon = latLon.Error.Lon * 2; // box size(in degree) on west-east direction
var lonStep = Math.Round((boxRight.Minimum.Lon - boxLeft.Minimum.Lon) / perLon);
double perLat = latLon.Error.Lat * 2; // box size(in dgree) on north–south direction
for (var lon = 0; lon <= lonStep; lon++)
{
// Find current box
string currentBoxHash = GeoHash.Neighbor(hashLeft, new[] { 0, lon });
NGeoHash.BoundingBox currentBox = GeoHash.DecodeBbox(currentBoxHash);
// Find north(upper) end
// Find up neighbor
// Check if in range
int i = 0;
NGeoHash.BoundingBox upBox = currentBox;
string upBoxHash = currentBoxHash;
while (BoxInCircleRange(upBox, latitude, longitude, radius))
{
if (!hashList.Contains(upBoxHash))
{
hashList.Add(upBoxHash);
}
//Console.WriteLine("Add+ " + upBoxHash);
i++;
upBoxHash = GeoHash.Neighbor(currentBoxHash, new[] { i, 0 });
upBox = GeoHash.DecodeBbox(upBoxHash);
}
// Find south(down) end
// Find steps(north to south)
int j = 0;
NGeoHash.BoundingBox downBox = currentBox;
string downBoxHash = currentBoxHash;
while (BoxInCircleRange(downBox, latitude, longitude, radius))
{
if (!hashList.Contains(downBoxHash))
{
hashList.Add(downBoxHash);
}
//Console.WriteLine("Add- " + downBoxHash);
j--;
downBoxHash = GeoHash.Neighbor(currentBoxHash, new[] { j, 0 });
downBox = GeoHash.DecodeBbox(downBoxHash);
}
}
// Check each point on the circle, see if covers more box
// Find step length of radius
double stepOfRadius = FindMinSideLength(hashCenter) * 0.9;
// Find step of cricle, devide 360 degree to how many parts
double stepOfCircle = 360 / (Math.PI * 2 * radius / stepOfRadius);
for (double degree = 0; degree <= 360; degree += stepOfCircle)
{
Coordinates coor = DistanceToPoint(latitude, longitude, radius, degree);
string hash = GeoHash.Encode(coor.Lat, coor.Lon, numberOfChars);
if (!hashList.Contains(hash))
{
hashList.Add(hash);
}
}
return(hashList.ToArray());
}
