Developer Guide - 2.7.3.2


INTRODUCTION

What is CoordinateSharp?

CoordinateSharp is a simple .NET Standard library designed to assist with geographic coordinate conversions, formatting and location based celestial calculations. CoordinateSharp has the ability to convert various Geodetic lat/long formats, UTM, MGRS(NATO UTM) and Cartesians (X, Y, Z). It also provides a wide array of location based solar/lunar information such as rise/set times, phase info and more.

Prerequisites

.NET 4.0 or greater or .NET Standard 2.0, 1.4, 1.3 Supported Platforms

Installation

CoordinateSharp is available as a nuget package from nuget.org

Alternatively, you may download the library directly here.

Updates and Changes

Change notes can be viewed here

Questions and Issues

If you have any issues or questions create an issue on our GitHub Project Page.



CONTENTS



COORDINATES (GEODETIC)


Creating a Coordinate Object

The Coordinate object is the "main" class of this library. For the most part, it contains all of the information you will need. The following method is one of the most basic ways to create a Coordinate.

//Seattle coordinates on 5 Jun 2018 @ 10:10 AM (UTC)
Coordinate c = new Coordinate(47.6062, -122.3321, new DateTime(2018,6,5,10,10,0));

Console.WriteLine(c);                       // N 47º 36' 22.32" W 122º 19' 55.56"
Console.WriteLine(c.CelestialInfo.SunSet);  // 5-Jun-2018 4:02:00 AM
Console.WriteLine(c.UTM);                   // 10T 550200mE 5272748mN

Parsing a Coordinate From a String

CoordinateSharp has the ability to parse a Coordinate from a provided string.


Coordinate.TryParse()

The Coordinate.Parse() method is a quick way to parse a coordinate string into a Coordinate object. It will throw exceptions if it fails however, so it important that proper exception handling be implemented when using this method. If the input string is uncontrolled, it is recommend that the TryParse() method below be used instead.

string s = "34X 551586mE 8921410mN"; //UTM Coordinate
Coordinate c = Coordinate.Parse(s);


Coordinate.TryParse()

The advantage of TryParse() is that you do not have worry about an invalid format throwing an exception. TryParse() will return a bool value instead signaling whether the parse was successful.

string s = "34X 551586mE 8921410mN"; //UTM Coordinate
Coordinate c; //Create new Coordindate to populate
if(Coordinate.TryParse(s, out c))
{
    //Coordinate parse was successful
    //Coordinate object has now been created and populated
    Console.WriteLine(c); //N 80º 20' 44.999" E 23º 45' 22.987"   
}

You may also parse with a GeoDate and/or EagerLoading specification using an overload with either parser.

If you need to work with Latitudes and Longitudes individually you may use the CoordinatePart.Parse() or CoordinatePart.TryParse() method.

Coordinate c = new Coordinate();
c.GeoDate = DateTime.Now //Date needed if grabbing celestial info

CoordinatePart lat;
CoordinatePart.TryParse("N 45.65", out lat);

CoordinatePart lng;
CoordinatePart.TryParse("W 15.58", out lng);
c.Latitude = lat;
c.Longitude = lng;

Because there are multiple types of Cartesian coordinates, you may need to specify what cartesian system you intend for your parser to work in. Spherical Cartesian is the default method, but it may be changed using an overload.

//Specifies input is in ECEF if X, Y, Z coordinate parses successfully.
Coordinate.TryParse(s, CartesianType.ECEF, out c);

The coordinate parser will be expanded constantly so provided suggestions on formats that should parse are greatly appreciated.


Creating a Coordinate From Other Degree Values

The Coordinate constructor only accepts Latitude and Longitude in signed degrees. With that said you can still create a Coordinate with other formats. For latitude / longitude type coordinates you can build a Coordinate using the method below.

It should be noted that this method is expensive if eager loading is being used (explained later in this guide). Eager loading is turned on by default, so using this method will cause all conversions to occur 3 separate times (once during Coordinate creation, and once for each CoordinatePart). This expense is usually negligible, but may become a factor during bulk or heavy usage.

//DMS Formatted: N 40º 34' 36.552" W 70º 45' 24.408.
Coordinate c = new Coordinate();
c.Latitude = new CoordinatePart(40,34, 36.552, CoordinatesPosition.N);
c.Longitude = new CoordinatePart(70, 45, 24.408, CoordinatesPosition.W);
c.Latitude.ToDouble();  // Returns 40.57682  (Signed Degree)
c.Longitude.ToDouble(); // Returns -70.75678 (Signed Degree)

To create a Coordinate using a format other than latitude & longitude (such as UTM), either use the TryParse() method OR reference the appropriate section of this document for further instruction.


Formatting a Coordinate Output

The default output of a Coordinate or Coordinate.ToString() is in DMS format. Formats may be changed by passing or editing the FormatOptions property contained in the Coordinate object.

Coordinate c = new Coordinate(40.57682, -70.75678);

c.FormatOptions.CoordinateFormatType = CoordinateFormatType.Degree_Decimal_Minutes;
c.FormatOptions.Display_Leading_Zeros = true;
c.FormatOptions.Round = 3;

c.ToString();           // N 40º 34.609' W 070º 045.407'
c.Latitude.ToString();  // N 40º 34.609'
c.Longitude.ToString(); // W 070º 45.407'
CoordinateFormatType Output
Decimal 40.577 -70.757
Decimal_Degree N 40.577º W 70.757º
Degree_Decimal_Minutes N 40º 34.609' W 70º 45.407'
Degree_Minutes_Seconds N 40º 34' 36.552" W 70º 45' 24.408"


Coordinate Conversion Formats


Universal Transverse Mercator and Military Grid Reference System

UTM and MGRS (NATO UTM) formats are available for display. They are converted from the lat/long decimal values. The default ellipsoid is WGS84 but a custom ellipsoid may be passed. These formats are accessible from the Coordinate object.

Coordinate c = new Coordinate(40.57682, -70.75678);
c.UTM.ToString(); // Outputs 19T 351307mE 4493264mN
c.MGRS.ToString(); // Outputs 19T CE 51307 93264

The UTM/MGRS systems will automatically switch to and display their polar system counterparts once polar regions are entered. UTM's polar counterpart is the Universal Polar Stereographic (UPS) and MGRS uses the MGRS Polar system. You may check which system is in use with the SystemType property. This property has replaced the WithinCoordinateSystemBounds property which was previously checked.

Coordinate c = new Coordinate(-85,10);

Console.WriteLine(c.MGRS.SystemType); //MGRS_Polar;
Console.WriteLine(c.UTM.SystemType); //UPS;

To convert UTM or MGRS coordinates into Lat/Long.

UniversalTransverseMercator utm = new UniversalTransverseMercator("T", 32, 233434, 234234);
Coordinate c = UniversalTransverseMercator.ConvertUTMtoLatLong(utm);

You may change or pass a custom ellipsoid by using the Equatorial Radius (Semi-Major Axis) and Inverse of Flattening of the datum. This will cause UTM/MGRS conversions to be based on the new ellipsoid.

Note Regarding Datums: When setting a custom "ellipsoid" you aren't truly setting a datum point, but a reference ellipsoid. This library isn't designed for mapping and has no way of knowing how a coordinate correlates with an actual map. This is solely used to changed the earth's shape during calculations to increase accuracy in specific regions. In most cases the default datum value is sufficient.

To change the current ellipsoid

//Ellipsoid is set on the Coordinate object for UTM/MGRS
c.Set_Datum(6378160.000, 298.25);

To create an object with the custom ellipsoid.

UniversalTransverseMercator utm = new UniversalTransverseMercator("Q", 14, 581943.5, 2111989.8, 6378160.000, 298.25);
c = UniversalTransverseMercator.ConvertUTMtoLatLong(utm);

There may be times in which you wish to remain in a single grid zone and "over-project" past its boundaries. This is often useful if a small section of a mapped area extends into a neighboring grid zone. We can accomplish over-projection by locking the latitudinal grid zone. It should be noted however, that over-projection will result in a loss of precision. It is up to each user to determine if precision loss is acceptable.

//Create a coordinate that projects to UTM Grid Zone 31
Coordinate coord = new Coordinate(51.5074,1); 
//Display normal projected UTM
Console.WriteLine(coord.UTM); //31U 361203mE 5708148mN

//Lock coordinate conversions to Grid Zone 30 (over-project);
coord.Lock_UTM_MGRS_Zone(30);

//Display over-projected UTM
Console.WriteLine(coord.UTM); //30U 777555mE 5713840mN 
//Approximately 1 meter of precision lost with a 1° (111 km / 69 miles) over-projection.

Some UTM formats may contain a "Southern Hemisphere" boolean value instead of a Lat Zone character. If this is the case for a UTM you are converting, just use any southern hemisphere letter (ex. "C") for southern hemisphere UTMs and any northern hemisphere letter (ex. "N") for northern hemisphere UTMs.

//MY UTM COORD ZONE: 32 EASTING: 233434 NORTHING: 234234 (NORTHERN HEMISPHERE)
UniversalTransverseMercator utm = new UniversalTransverseMercator("N", 32, 233434, 234234);
Coordinate c = UniversalTransverseMercator.ConvertUTMtoLatLong(utm);

NOTE: Certain softwares handle near polar region coordinates differently due to the conic shape of grid zones when nearing the edges of system limitations. Some softwares choose to skip grid zone designations in order to widen the grid zone being returned during conversion. This is normal and both softwares are accurate due to grid overlap. This is most obvious in the N80-N84 regions prior to entering UPS/MGRS Polar.

For example N 80, E 7 will return different UTM/MGRS coordinates between www.earthpoint.us and CoordinateSharp.

Software UTM MGRS
Earthpoint 31X 577483mE 8884250mN 31X EJ 77483 84250
CoordinateSharp 32X 461235mE 8882252mN 32X MP 61235 82252

Both coordinates will convert back to approximately N 80, E 7 in both softwares. This discrepancy is important however, as it could lead to test/expectation failures if not handled correctly.


NOTE: US ARMY TEC-SR-7 1996 was referenced for UPS/MGRS POLAR conversions implemented in 2.4.1.1.

During testing it was noted that the formulas suffer accuracy loss during convert backs (converting UPS/MGRS POLAR back to GEODETIC LAT/LONG). This accuracy loss ranges from 0-33 meters below the 88th parallel and 66 meters up to 2.2 kilometers above the 88th parallel (greatest precision loss occurs near poles).

It is important that users working in polar regions understand these precision limitations. Other software/tools will experience similar precision losses due to the nature of the system, but there may be more accurate polar tools available if higher precision is required.


NOTE: CoordinateSharp uses math based calculations to determine converted coordinates. This library does not attempt to correct for modified zones (ex Norway).


MGRS Grid Boxes

It may be necessary at times to determine MGRS 100km square corner points. You can calculate estimate grid boundaries using the MGRS_GridBox class. Both MGRS and Lat/Long points can be obtained. It should be noted that CoordinateSharp will automatically attempt to correct false MGRS points. The MGRS_GridBox feature cannot do this though, so users should always determine if the passed MGRS coordinate is valid. Example below.

//Create MGRS Coordinate at a Grid Zone Junction Point (partial square)
MilitaryGridReferenceSystem mgrs = new MilitaryGridReferenceSystem("N", 21, "SA", 66037, 61982);

//Set EagerLoad to MGRS only for efficiency
//Only applicable if pulling Lat/Long Coordinate values from box corners
EagerLoad el = new EagerLoad(EagerLoadType.UTM_MGRS);

var gb = mgrs.Get_Box_Boundaries(el);

//Check if box is Valid first (if not corners will be null)
if(!gb.IsBoxValid){return;}

//Get Bottom Left MGRS Object
gb.Bottom_Left_MGRS_Point; //21N SA 66022 00000

//Get Bottom Left Corodinate Object
//Will throw exception if MGRS is not valid.
gb.Bottom_Left_Coordinate_Point; //N 0º 0' 0" W 59º 59' 59.982"

Cartesian Format

Spherical Earth Cartesian (X, Y, Z) is available for display. They are converted from the lat/long radian values. This format is accessible from the Coordinate object. You may also convert a Cartesian coordinate into a lat/long coordinate. This conversion uses the Haversine formula. It is sufficient for basic application only as it assumes a spherical earth.

To Cartesian:

Coordinate c = new Coordinate(40.7143538, -74.0059731);
c.Cartesian.ToString(); //Outputs 0.20884915 -0.72863022 0.65228831

To Lat/Long:

Cartesian cart = new Cartesian(0.20884915, -0.72863022, 0.65228831);
Coordinate c = Cartesian.CartesianToLatLong(cart);
//OR
Coordinate c = Cartesian.CartesianToLatLong(0.20884915, -0.72863022, 0.65228831);

ECEF Format

Earth Centered Earth Fixed (ECEF) Cartesian coordinates are available. The are converted using the WGS84 ellipsoid by default, but the ellipsoid may be changed by using the SetDatum() function. There is no geoid model included in this conversion.

To ECEF:

Coordinate c = new Coordinate(40.7143538, -74.0059731);
c.ECEF.ToString(); //Outputs 1333.97 km, -4653.936 km, 4138.431 km

To Lat/Long:

ECEF ecef = new ECEF(1333.97, -4653.936, 4138.431);
Coordinate c = ECEF.ECEFToLatLong(ecef);
//OR
Coordinate c = ECEF.ECEFToLatLong(1333.97, -4653.936, 4138.431);

When converting from ECEF to GeoDetic Lat/Long, the altitude or height from the conversion may be desired. The post conversion height may be accessed in the ECEF class using the Distance object GeoDetic_Height. You may also set the height of the coordinate for ECEF conversions by using the Set_GeoDetic_Height(). ECEF height starts at Mean Sea Level (MSL) based on the provided ellipsoid.

NOTE: ECEF.GeoDetic_Height will always be set at 0 unless a coordinate is converted from ECEF to Lat/Long or the value is manually updated using ECEF.Set_GeoDetic_Height().

Setting the GeoDetic height for ECEF conversions:

Coordinate c = new Coordinate(45 , 45);
c.ECEF.ToString(); //Outputs 3194.419 km, 3194.419 km, 4487.348 km

c.ECEF.Set_GeoDetic_Height(c, new Distance(1000, DistanceType.Meters));
c.ECEF.ToString(); //3194.919 km, 3194.919 km, 4488.056 km

Getting the GeoDetic height after converting from ECEF to Lat/Long:

ECEF ecef = new ECEF(1333.97, -4653.936, 4138.431);
Coordinate c = ECEF.ECEFToLatLong(ecef);
c.ECEF.GeoDetic_Height.Meters; //Outputs 1000.2

The GeoDetic height will need to be set if creating a new Coordinate based on an existing Coordinate. These fundementals may become applicible if working with EagerLoading.

Distance geoHeight = c.ECEF.GeoDetic_Height;
Coordinate newCoordinate = new Coordinate(c.Latitude.ToDouble(), c.Longitude.ToDouble());
newCoordinate.ECEF.Set_GeoDetic_Height(newCoordinate, geoHeight);


Celestial Information


Accessing Celestial Data

Solar and lunar information is made available by passing a date to a Coordinate. You may initialize a Coordinate object with a date or pass it later. CoordinateSharp operates in UTC by default, so all dates will be assumed in UTC regardless of the specified DateTimeKind. You may however operate in local time by specifying the Coordinate object's Offset value should you choose.

Accessing celestial information example (all times will be in UTC).

//UTC Date 21-MAR-2019 @ 11:00 AM
DateTime d = new DateTime(2017,3,21,11,0,0);
Coordinate c = new Coordinate(40.57682, -70.75678, d);
c.CelestialInfo.SunRise.ToString(); //Outputs 3/21/2017 10:45:00 AM

Local time operation example.

//EST Date 21-MAR-2019 @ 07:00 AM
DateTime d = new DateTime(2017,3,21,7,0,0);
Coordinate c = new Coordinate(40.57682, -70.75678, d);

//Coordinate still assumes the date is UTC, so we must specify the local offset hours.
c.Offset = -4; //EST is UTC -4 hours

c.CelestialInfo.SunRise.ToString(); //Outputs 3/21/2017 06:45:00 AM

Available Celestial Data

The following pieces of celestial information are currently available:

DATA TYPE SUN MOON
Rise * *
Set * *
Noon *
Altitude * *
Azimuth * *
Distance *
Illumination *
Perigee *
Apogee *
Dawns *
Dusks *
Eclipse * *
Zodiac * *
Solstice *
Equinox *

Checking if Celestial Body Is Up

You may check if the Sun or Moon is currently "up" by using the IsSunUp or IsMoonUp boolean properties. The value returned is based on the provided location, GeoDate and Offset hours provided. The Sun and Moon are considered "Up" based on the body's rise/set times.

c.CelestialInfo.IsSunUp; //returns true or false

Checking Celestial Body Conditions

IMPORTANT: Sun/Moon Set and Rise DateTimes are nullable. If a null value is returned the Sun or Moon Condition needs to be viewed to see why. It is recommended that you always check this. Because CoordinateSharp works on a "event per day" basis and not a "next event" basis, you may have days with no rise or no set.

This becomes especially apparent in the spring when solar cycles are greater than 24 hours due to growing daylight. Once a year you will have a day with no rise or set in certain regions of the world if working in UTC/ZULU time.

Coordinate c = new Coordinate(85.57682, -70.75678, new DateTime(2017,8,21));
c.CelestialInfo.SunRise; //Outputs null
c.CelestialInfo.SunCondition; //Outputs UpAllDay

If you wish to work in a "last" or "next" event basis, you may do so using static functions. This is advantageous if you wish to return a guaranteed rise or set time. It should be noted that this method can become expensive as you move towards the poles as rise and sets may not occur for weeks or month at a time.

DateTime d = new DateTime(2019, 2, 6);
DateTime val = Celestial.Get_Next_SunRise(40.0352, -74.5844, d);

Moon Illumination and Phase

Moon Illumination returns a value from 0.0 to 1.0. The table shown is a basic break down. You may determine Waxing and Waning types between the values shown using Celestial.MoonIllum.Phase or you may get the phase name from the Celestial.MoonIllum.PhaseName property.

Value Phase
0.0 New Moon
0.25 First Quarter
0.5 Full Moon
0.75 Third Quarter

It should be noted that when working in local time, the moons "phase name" may change if the UTC day is the previous or next day. There will also be times when the phase name does not match the news or certain websites. This normally occurs when the source is using the following morning's phase name. CoordinateSharp works in the exact time passed to capture phase name, not the phase name on a "certain night".

If you are unsure or do not prefer this behavior, you may tap into the Phase property to determine your own phase name.


Static Retrieval of Celestial Data

You may also grab celestial data through static functions if you do not wish to create a Coordinate object.

//UTC EXAMPLE
Celestial cel = Celestial.CalculateCelestialTimes(45.57682, -70.75678, new DateTime(2017,8,21));
cel.SunRise.Value.ToString();

//LOCAL TIME (EST) EXAMPLE
double utcOffsetHours = -4;
Celestial cel = Celestial.CalculateCelestialTimes(45.57682, -70.75678, new DateTime(2017,8,21), utcOffsetHours);
cel.SunRise.Value.ToString();

Determine Time of Day from Solar Altitude

If you wish to determine the time of day based on a provided date, coordinate point and solar altitude you may do so. The following feature will return a rising and setting transit event time. These values are nullable and should be checked for value before use.

//lat, long, date, altitude in degrees, UTC offset (if desired).
AltitudeEvents aev = Celestial.Get_Time_at_Solar_Altitude(47.4, -122.6, new DateTime(2020,8,11), 41.6, -7);

//Altitude point crossed time during solar rising
if(aev.Rising.HasValue)
{
     aev.Rising; //8/11/2020 10:22:12 AM 
}

//Altitude point crossed time during solar setting
if(aev.Setting.HasValue)
{
     aev.Setting; //8/11/2020 4:11:33 PM
}

Lunar Perigee and Apogee

Perigee and Apogee information is available in the Celestial class but may be called specifically as it is not location dependent.

Perigee p = Celestial.GetPerigee(date);
p.LastPerigee.Date;
p.LastPerigee.Distance.Kilometers;

Eclipses

Solar and Lunar Eclipse.

Coordinate seattle = new Coordinate(47.6062, -122.3321, DateTime.Now);
//Solar
SolarEclipse se = seattle.CelestialInfo.SolarEclipse;
se.LastEclipse.Date;
se.LastEclipse.Type;
//Lunar
LunarEclipse le = seattle.CelestialInfo.LunarEclipse;
se.NextEclipse.Date;
se.NextEclipse.Type;

You may also grab a list of eclipse data based on the century for the location's date.

List<SolarEclipseDetails> events = Celestial.Get_Solar_Eclipse_Table(seattle.Latitude.ToDouble(), seattle.Longitude.ToDouble(),  DateTime.Now);

Celestial Data Notes

NOTE REGARDING ACCURACY: Most celestial calculations use math based approximation algorithms. These approximations use average values for things like altitude, refraction and other atmospheric conditions. It is up to each user to determine if precision meets use case.

NOTE REGARDING ECLIPSE DATA: Eclipse data can only be obtained from the years 1601-2600. Thas range will be expanded with future updates.

NOTE REGARDING SOLAR/LUNAR ECLIPSE PROPERTIES: The Date property for both the Lunar and Solar eclipse classes will only return the date of the event. Other properties such as PartialEclipseBegin will give more exact timing for event parts.

Solar eclipses sometimes occur during sunrise/sunset. Eclipse times account for this and will not start or end while the sun is below the horizon.

Properties will return 0001/1/1 12:00:00 if the referenced event didn't occur. For example if a solar eclipse is not a Total or Annular eclipse, the AorTEclipseBegin property won't return a populated DateTime.



Time Zones


Getting Time Zone at Location

CoordinateSharp does not contain the ability by itself to acquire time zones for offsetting a UTC DateTime. This is a complicated process that involves keeping up with ever changing map data and time zone rules. With that said, it is understood that users of this library often have the need for this. The goal of this section is to assist with methods of accomplishing that goal.


The Two Part Process

Gathering time zone information based solely on a coordinate is a two part process.

  1. Acquire the IANA time zone ID using either a web service or a library.
  2. Determine the UTC offset using an IANA compliant date tool such as NodaTime.

1. Acquire the Time Zone ID

There are many tools that can grab a time zone ID based on a provided coordinate, but all have issues. For instance, implementing a library is great in that you do not rely on a web service to provide that data for you. The problem with this method however is that time zones change globally. Every time there is a change you must not only update the library you are using, but hope the developers maintaining the library get the change out in time.

Web services like Google or Bing Maps on the other hand are great in that they are usually up to date. The problem with web services however is that they will rate limit you unless you pay money. Furthermore, they require an internet connection to work. It's really a "pick your poison" type situation. Check out this Stack Overflow post for a great list of services and libraries that can help you decide which tool works best for you.

For the purposes of this very basic example, we'll be using the Google Maps API. You will most likely need an API key to use this. It can be obtained from the Google Developer Console

First we need a data model to handle the Google Map Request.

public class GoogleTimeZone
{
   public double dstOffset { get; set; }
   public double rawOffset { get; set; }
   public string status { get; set; }
   public string timeZoneId { get; set; }
   public string timeZoneName { get; set; }
}

Next we need a DateTime extension method to handle Google's time stamp requirements.

public static class ExtensionMethods
{
    public static double ToTimestamp(this DateTime date)
    {
        DateTime origin = new DateTime(1970, 1, 1, 0, 0, 0, 0);
        TimeSpan diff = date.ToUniversalTime() - origin;
        return Math.Floor(diff.TotalSeconds);
    }
}

Lastly we add a method to handle the RESTful API request to Google. This example is very basic. It is up to you to handle any errors or failed/denied requests.

using RestSharp; //RestSharp can be downloaded via Nuget.

public static string GetTimeZone(double latitude, double longitude)
{
     string ianaID;

     string key = "<your secret key>"; //MAP API KEY. Get from Google Developer Console.

     var client = new RestClient("https://maps.googleapis.com"); //Set the client
     var request = new RestRequest("maps/api/timezone/json", Method.GET); //Set the request type (timezone)

     //Add required parameters
     request.AddParameter("location", latitude + "," + longitude);
     request.AddParameter("timestamp", DateTime.Now.ToTimestamp());
     request.AddParameter("key", key);
    
     //Send the request to Google and await response
     var response = client.Execute<GoogleTimeZone>(request);      

     return ianaID = response.Data.timeZoneId;
}

Ok now we are set up to grab a time zone ID based on our Lat / Long.

Coordinate c = new Coordinate(42, -112, DateTime.Now);
string timezoneID = GetTimeZone(c.Latitude.ToDouble(), c.Longitude.ToDouble());
Console.WriteLine(timezoneID); //America/Boise

2. Determine the UTC Offset.

Luckily hard part is over. Thanks to the master of C# John Skeet, we can get the offset of the time zone we just acquired using his awesome library NodaTime.

using NodaTime; //Download from Nuget

DateTimeZone zone = DateTimeZoneProviders.Tzdb[tz];
DateTime d = DateTime.Now.ToUniversalTime(); //Date must have DateTimeKind of UTC
Instant instant = Instant.FromDateTimeUtc(Convert.ToDateTime(DateTime.Now.ToUniversalTime()));
Offset offset = zone.GetUtcOffset(instant);


Distances, Bearings and Moving Coordinates


Calculating Distance

Distance is calculated with 2 methods based on how you define the shape of the earth. If you pass the shape as a Sphere calculations will be more efficient, but less accurate. The other option is to pass the shape as an Ellipsoid. Ellipsoid calculations have a higher accuracy. The default ellipsoid of a coordinate is WGS84, but can be changed using the Coordinate.SetDatum function.

Distance can be calculated between two Coordinates. Various distance values are stored in the Distance object.

Distance d = new Distance(coord1, coord2); //Default. Uses Haversine (Spherical Earth)
//OR
Distance d = new Distance(coord1, coord2, Shape.Ellipsoid); 

d.Kilometers;
d.Bearing;

You may also grab a distance by passing a second Coordinate to an existing Coordinate.

coord1.Get_Distance_From_Coordinate(coord2).Miles;

Moving Coordinates

If you wish to move a coordinate based on a known distance and bearing you can do so with the Move function. Distance must be passed in meters. The coordinate values will update in place.

//1000 Meters
//270 degree bearing
coord1.Move(1000, 270, Shape.Ellipsoid);

You may also move a specified distance toward a target coordinate if you do not have a bearing toward it.

//Move coordinate 1 10,000 meters toward coordinate 2
coord1.Move(coord2, 10000, Shape.Ellipsoid);

The option to create a Distance for conversion purposes only also exists.

Distance d = new Distance(20, DistanceType.NauticalMiles);
d.Meters; //Convert to meters.


Binding


Binding and MVVM

The properties in CoordinateSharp implement INotifyPropertyChanged and may be bound. If you wish to bind to the entire CoordinatePart bind to the Display property. This property can be notified of changes, unlike the overridden ToString(). The Display will reflect the formats previously specified for the Coordinate object in the code-behind.

Output Example:

<TextBlock Text="{Binding Latitude.Display, UpdateSourceTrigger=PropertyChanged}"/>

Input Example:

<ComboBox Name="latPosBox" VerticalAlignment="Center" SelectedItem="{Binding Path=DataContext.Latitude.Position, UpdateSourceTrigger=LostFocus, Mode=TwoWay}"/>
<TextBox Text="{Binding Latitude.Degrees, UpdateSourceTrigger=LostFocus, Mode=TwoWay, ValidatesOnExceptions=True}"/>
<TextBox Text="{Binding Latitude.Minutes, UpdateSourceTrigger=LostFocus, Mode=TwoWay, ValidatesOnExceptions=True}"/>
<TextBox Text="{Binding Latitude.Seconds, StringFormat={}{0:0.####}, UpdateSourceTrigger=LostFocus, Mode=TwoWay, ValidatesOnExceptions=True}"/>

NOTE: It is important that input boxes be set with 'ValidatesOnExceptions=True'. This will ensure UIElements display input errors when incorrect values are passed.



Julian Dates


Julian Date Conversions

The Julian date converters used by the library have been exposed for use. The converters account for both Julian and Gregorian calendars.

//To Julian
double jul = JulianConversions.GetJulian(date);
 
//From Julian
DateTime date = JulianConversions.GetDate_FromJulian(jul));
 
//Epoch options also exist
JulianConversions.GetJulian_Epoch2000(date);


Geo-Fencing


Creating Geo-Fences

Both line and polygon boundaries may be specified using the GeoFence class. Once Points have been specified you may compare them to a Coordinate to determine if it is within bounds.


List<GeoFence.Point> points = new List<GeoFence.Point>();

//Points specified manually to create a square in the USA.
//First and last points should be identical if creating a polygon boundary.
points.Add(new GeoFence.Point(31.65, -106.52));
points.Add(new GeoFence.Point(31.65, -84.02));
points.Add(new GeoFence.Point(42.03, -84.02));
points.Add(new GeoFence.Point(42.03, -106.52));
points.Add(new GeoFence.Point(31.65, -106.52));

GeoFence gf = new GeoFence(points);


Coordinate c = new Coordinate(36.67, -101.51);

//Determine if Coordinate is within polygon
gf.IsPointInPolygon(c);

//Determine if Coordinate is within specific range of shapes line.
gf.IsPointInRangeOfLine(c1, 1000); //Method 1 specify meters.

Distance d = new Distance(1, DistanceType.Kilometers);
gf.IsPointInRangeOfLine(c1, d); //Method 2 specify Distance object.

There may be times in which you do not know the specific coordinates for a Geo-Fence, but rather need to draw a shape using distances and bearings. Due to the shape of the earth, the initial bearing of a line may not match the final bearing. This can cause shapes drawn to be very inaccurate. To assist with this, you can make use of the GeoFence.Drawer class. This drawing class will automatically adjust for bearing shifts due to the shape of the earth.

//DRAW A 5KM SQUARE
//THIS EXAMPLE TURNS RIGHT 90 DEGREES AFTER EACH LINE IS DRAWN

//Create a Coordinate at the starting location
//Eager loading is off for efficiency as every point will calculate if it's on.
Coordinate c = new Coordinate(35.68919, 51.38897, new EagerLoad(false));

//Create the GeoFence.Drawer with an initial bearing facing 0 degrees
GeoFence.Drawer gd = new GeoFence.Drawer(c, Shape.Ellipsoid, 0);

gd.Draw(new Distance(5), 0); //Draw the first line maintaining the initial bearing
gd.Draw(new Distance(5), 90); //Change the bearing 90 degrees and draw the second line
gd.Draw(new Distance(5), 90); //Change the bearing 90 degrees and draw the third line
gd.Close(); //Close the shape by drawing a line to the starting location

//Iterate each point drawn and print its location.
foreach (var coord in gd.Points)
{
     Console.WriteLine("{0}, {1}", coord.Latitude.ToDouble(), coord.Longitude.ToDouble());
}


Eager Loading


Eager Loading Basics

CoordinateSharp values are all eager loaded upon initialization of a Coordinate object by default. Anytime a Coordinate property changes, everything is recalculated. You may wish to turn off eager loading if you are trying to maximize performance. This will allow you to specify when certain calculations take place.

NOTE: The default eager loading behavior may be adjusted in the global settings. See Global Settings for details.

Below is a basic example of how to adjust a Coordinate object's eager loading behavior. The will turn off eager loading of the CelestialInfo property.

EagerLoad eagerLoad = new EagerLoad();
eagerLoad.Celestial = false;
//Create Coordinate with the specified eager loading settings
Coordinate c = new Coordinate(40.0352, -74.5844, DateTime.Now, eagerLoad);
//To load Celestial data when ready
c.LoadCelestialInfo();

The above example initializes a Coordinate with eager loading in place. You may however turn it on or off for specific areas after initialization.

coordinate.EagerLoadSettings.Celestial = false;

You may also turn EagerLoading on/off for all available settings at once.

//Sets EagerLoading off for all properties (CelestialInfo, MGRS, UTM, Cartesian, ECEF)
EagerLoad eagerLoad = new EagerLoad(false);
Coordinate c = new Coordinate(40.0352, -74.5844, DateTime.Now, eagerLoad);

Enum flags with a declared object or static function may be used. Only the passed flags will EagerLoad.

EagerLoadType et = EagerLoadType.Celestial | EagerLoadType.Cartesian;

EagerLoad eagerLoad = new EagerLoad(et);
//OR
EagerLoad eagerLoad = EagerLoad.Create(et); //Returns new EagerLoad

A more in depth look at eager loading can be found on our Performance Tips page.



Global Settings


Global Settings Usage

Application wide global settings may be adjusted to modify the default behavior of certain aspects within CoordinateSharp. This is a great feature if you wish to set a behavior one time for the entire application. This will save the developer from having to specify an EagerLoad or CoordinateFormatOptions each time a Coordinate is created.

Global settings should be specified at application start up. Treating these settings as a dynamic values could have unwanted behavior, especially in multi-threaded environments. It is highly recommend you do not adjust these values once they have been modified.

You may currently adjust the following default.

Default Setting Property Name
Eager Loading Behavior Default_EagerLoad
Coordinate Format Output Behavior Default_CoordinateFormatOptions

The below example will change the application wide default eager loading settings from all properties eager loading to UTM/MGRS only.

GlobalSettings.Default_EagerLoad = new EagerLoad(EagerLoadType.UTM_MGRS);

The below example will change the application wide Coordinate default output from DMS to DDM.

GlobalSettings.Default_CoordinateFormatOptions = new CoordinateFormatOptions() 
{ Format = CoordinateFormatType.Degree_Decimal_Minutes  };


Benchmarks


Benchmark Results

The following Coordinate procedures were benchmarked as follows.

Method i7-8550U 1.80GHz 1.99 GHz (x64)
Standard Initialization 8 ms
TryParse() Initialization 6-35 ms
Secondary Initialization 30 ms
Initialization w/EagerLoad off < 1 ms
Property Change 7 ms
Total Celestial (Local/UTC) 8 ms
Solar Cycle Only (Local/UTC) < 1 ms
Lunar Cycle Only (Local/UTC) 2 ms


Credit


Acknowledgements

Most celestial calculations are based on "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.

Certain solar algorithms were adapted from NOAA and Zacky Pickholz 2008 "C# Class for Calculating Sunrise and Sunset Times" NOAA The Zacky Pickholz project

Certain lunar calculations were adapted from the mourner / suncalc project (c) 2011-2015, Vladimir Agafonkin suncalc & These Formulas by Dr. Louis Strous

Calculations for illumination parameters of the moon based on NASA Formulas and Chapter 48 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.

UTM & MGRS Conversions were referenced from Sami Salkosuo's j-coordconvert library & Steven Dutch, Natural and Applied Sciences,University of Wisconsin - Green Bay

ECEF Conversions were referenced from works by James R. Clynch

Solar and Lunar Eclipse calculations were adapted from NASA's Eclipse Calculator created by Chris O'Byrne and Fred Espenak.

Aspects of distance calculations referenced worked by Ed Williams Great Circle Calculator

Graphic and logo design work was donated by area55.

All GitHub users who contribute code and/or create issues!