geo

The geo.py module is a BlueSky tool that defines a set of standard geographic functions and constants for coding in BlueSky. The tool can be imported using:

...
from bluesky.tools import geo
...

Some standard geographic functions available include:

1. Calculating the earth's radius [m] with the World Geodetic System WGS'84 geoid definition. The input used in this function is the latitude [deg]. External reference.

Example 1:

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IN: lat1 = 53 
# call function and compute earth's radius using WGS84 definition 
Radius = rwgs84(lat1)
print(Radius)
OUT: 6364538.974408425
...

2. Calculating the bearing and distance using WGS84 definition.

Example 2:

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IN: 45, 12, 52, 2 (latd1,lond1, latd2, lond2)
# call function and compute the bearing and distance \[nm\] 
qdr, dist = qdrdist(45, 12, 52, 2 )

print(qdr,dist)
OUT: -39.76323481565359 577.2634174193117
...

3. Calculating the distance using the haversine formulae with input lat/lon in degrees and major semi-axis (a = 6378137.0). An example is given below:

Example 3:

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IN: 45, 12, 52, 2 (latd1,lond1, latd2, lond2)
# call function and compute distance \[m\] 
d = latlondist(45,12,52,2)
print(d)
OUT: 1069091.8490605652
...

4. Calculating the gravity acceleration at a given latitude according to WGS'84 definition with input: gravity acceleration at the equator, which is 9.7803m/s^2; the earth's eccentricity, which is around 6.694e-3; and a constant k (0.001932), which is derived from the flattening. An example of this equation is shown below:

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IN: 45 (latd)
# call function and compute gravity acceleration for the given latitude \[deg\]
gravity = wgsg(45)
print(gravity)
OUT: 9.806172153520823
...

There are also some useful formula for getting some fast approximations; for example the reference position of your aircraft and distance. More information on this can be found in geo.py.