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savage13 / SAC-Bugs

Bugs for SAC
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Distance Calculation #6

Open savage13 opened 12 years ago

savage13 commented 12 years ago

What is the defined ellipsoid for the distance calculation ? Where is the distance calculation defined and derived ?

savage13 commented 12 years ago

Well. I looked into this. The documentation says it is based on the "Reference Spheroid of 1968". I tried to find this reference, but came up empty.

In the distaz() function ellipsoid is defined with a Radius of 6378.160 km and the flattening is 0.00335293 = 1/298.24660819044

The nearest ellipsoid is Geodetic Reference System 1967 R = 6378.160, f=1/298.247167427

I attempted to match the distaz() ellipsoid reference to an array of existing ellipsoids but was unsuccessful.

The method to calculate the distance in kilometers is somewhat more mysterious. The reference is from 1980 4th edition of Geodesy by Bomford and Rudoe's formula is difficult to find on the internet. The first edition (1952) of Geodesy, I found online does not have a solid reference to Rudoe's formula, only a "unpublished manuscript". I am hoping to get my hands on the 4th edition at some point.

I hope this helps. Looking into this, it would be appropriate to use something a bit more up to date, like WGS 84 used in GPS systems.