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Horizontal angles, directions and zenith angles in gama-local
XML adjustment input are implicitly given in gons and their standard
deviations and/or variances in centicentigons. Gon, also called
centesimal grade and Neugrad (German for new grad), is 1/400-th of the
circumference. For example
<direction from="202" to="416" val="63.9347" stdev="10.0" /> |
The same angular value (direction) can be expressed in degrees (sexagesimal graduation) as
<direction from="202" to="416" val="57-32-28.428" stdev="3.24" /> |
In XML adjustment input degrees are coded as a single string, where degrees (57), minutes (32) and seconds (28.428) are separated by dashes (-) with optional leading sign. Spaces are not allowed inside the string. Gons and degrees may be mixed in a single XML document but one should be careful to supply the information on standard deviations and/or covariances in the proper corresponding units.
Sexagesimal seconds (ss) are commonly called arcseconds, they are related to the metric system centicentigons (cc) as
ss = cc/400/100/100 * 360*60*60 = cc*0.324.
Internally gama-local
works with gons but output can be
transformed to degrees using the option --angular 360
.
Another angular unit commonly used in surveying is the milligon (mgon), 1 mgon = 1 gon/1000 (similarly as 1 mm = 1 m/1000) and 10 cc = 1 mgon.
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This document was generated on February 17, 2024 using texi2html 1.82.