🚀 go-pugleaf

On Wed, 02 Jul 2003 20:27:46 GMT, JF Mezei <jfmezei.spamnot@istop.com>
wrote in news:3F03403D.2909214E@istop.com: 

> "Dave Null Sr." wrote:
>> By CO I assume you mean Central Office. Shirley you can simply
>> locate them and use another map to determine a more accurate
>> pair of co-ordinates?
> 
> Stop calling me Shirley...
> 
> Locating them with some of the online maps can be done with fairly
> impressive accuracy with regards to the latitude longitude (which you
> would find tucked into the url of the zoom/location level being shown).
> 
> However, if the all mighty Ralph has a large table of V&H coordinates,
> then locating individual ones on an interacctive map would be very time
> consuming. 
> 
> From the giv image that was links by another poster, it seems the origin
> of V&H would be somewhere over the caribeean. If you could find the
> exact lat/lon for that point of origin, then one could calculate lat/lon
> fairly easily for any v&H point.
> 
> HOWEVER: what is not clear in that gif image is whether it takes the
> curvature of earth into consideration. LAT-LON do. The math formulas
> calculate a portion of circumference passing through two points. On a
> continental scale (north america), this does make quite a difference. On
> a city scale, perhaps not much of a difference.

lat/long is NOT a projection, which is what all flat maps are.
Projection systems and datums use an approximation to balance
various trade-offs for accuracy in distance, area, or other considerations
such as size of the area being mapped.

Projection systems can drop a cone or a cylinder (...) over the globe
and then unfold them to a flat surface (in virtual terms).
Errors are known and calculated, but there are errors.