NautiPy

NautiPy is an open-source Python library for nautical navigation applications.

ISO 6709 Coordinates

The library uses a float representation of GPS coordinates, based on the ISO 6709 standard (without left padding zeros), i.e.

• Latitude: ±DD.D (e.g. +50.12257)
• Longitude: ±DDD.D (e.g. +8.66370)

Coordinate Conversion

The convert_coordinates function allows for conversion between various GPS input formats to ISO 6709 decimal degrees. Supported input formats include:

• Degrees, Minutes, Seconds (DMS): e.g. "N 50° 7' 20.9122", "W 8° 39' 56.52"
• Degrees and Decimal Minutes (DMM): e.g. "50° 7.34854N", "8° 39.942W"
• Decimal Degrees (DD): e.g. "+50.12257", "-8.66570"

Example usage:

# Convert different formats to ISO 6709 (decimal degrees)
print(convert_coordinates("+50.12257", "-8.66570", "DD"))
print(convert_coordinates("N 50° 7' 20.9122", "W 8° 39' 56.52", "DMS"))
print(convert_coordinates("50° 7.34854N", "8° 39.942W", "DMM"))

Functionalities

Basics

# Store and descibe your position
work = Pos(50.127198, 8.665562, desc='Campus building')
print(f'Work is here: {work.coordinates()}')

# Get relative position, e.g. heading 90 degrees 12 kilometers away
work_displaced = work.displace(90, 12)

# Get bearing to or from position
bearing(work, work_displaced)

# Get distance to position
haversine(work, work_displaced)

# Consider the following known stations
stations = [Pos(50.116135, 8.670277, 'Opernturm'),
            Pos(50.112836, 8.666753, 'Deka tower'),
            Pos(50.110347, 8.659873, 'Volksbank tower')
            ]

# Get the nearest stations within a radius around your position
nearest = nearest_stations(work, stations, radius=1.7)
print(f'{[(p.desc, d) for p, d in nearest]}')

Triangulation and Multilateration

To fix a position both methods rely on knowledge about the position and bearing to 2 (triangulation) or position and distance to 3 (multilateration) stations.

In trigonometry and geometry, triangulation is the process of determining the location of a point by forming triangles to it from known points. (Wikipedia)

# Get your position from bearings to two stations
triangulate(stations[0], 164.71, stations[2], 192.22).coordinates()

True range multilateration is a method to determine the location of a movable vehicle or stationary point in space using multiple ranges (stations) between the vehicle/point and multiple spatially-separated known locations. (Wikipedia)

# Get your position from distances to at least 3 stations (you can use more)
#               position,      distance
multilaterate([(stations[0],  1.275251),  
               (stations[1],  1.599237),  
               (stations[2],  1.917145)]).coordinates()

Compare both positions to work, i.e. (50.127198, 8.665562).

Importing and exporting

NautiPy includes export_positions and import_positions functions to convert position data into GeoJSON format for easy use in GIS software and mapping services. It can save the output to a file or return the GeoJSON string.

Example Usage

# Export and save to a file
export_positions(stations, save_as="positions.geojson")

# Load positions from a GeoJSON file
stations_reloaded = import_positions('positions.geojson')