[mapguide-users] vector editing

[Jason Birch]

Heh.  I wasn't entirely serious; COGO is extremely tricky to do right.
 
Apart from being a field of mathematics, COordinate GeOmetry is also jargon for a way of creating features by entering their surveyed geometry on a command line.  It has traditionally been the realm of CAD tools, though ArcInfo Workstation had a COGO module, and I believe that the latest ArcGIS versions have had some COGO support.  With AJAX, this is something that could actually be considered for web-based feature creation.
 
It isn't as simple as X/Y entry.  This isn't my area of expertise, but I think that typically you start out with a well known point (GCP, monument, etc) and start from there.  Sometimes the first point in the feature is the well known point, but more frequently your feature's first point an offset from this reference.  From there, each additional coordinate in the feature is typically entered by azimuth and distance (curves are more complicated) until you get to the final point.  At the final point, closure error is determined.  You need to be able to adjust for different azimuth entry systems and units, and probably also deal with the local datum's scale factor.  We'd need survey and math expertise to help out.
 
Sound like fun?  Maybe in a year or so once we get a bit more feature-complete...  definitely not our first RFC ;)
 
Jason

________________________________

From: Paul Spencer [mailto:pspencer at dmsolutions.ca]
Sent: Sat 2006-10-28 11:10 AM
To: users at mapguide.osgeo.org
Subject: Re: [mapguide-users] vector editing



you lost me ... what is "command-line" COGO?

Cheers

Paul


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