🚀 go-pugleaf

On Wed, 02 Jul 2003 20:32:47 GMT, Tegger
<teggeratistopdotcom@changetheobvious.invalid> wrote in
news:_hHMa.4755$eF3.568687@news20.bellglobal.com: 

> Dave Null Sr. wrote:
>> On Tue, 01 Jul 2003 19:11:43 GMT, nobody@uunet.ca (Ralph) wrote in 
>> news:3f01dbc8.156431357@news2.istop.com:
>> 
>>>I'd like to convert CO V&H coords to Lat/Long.  I found a V&H map
>>>online, but it's a low-res gif so it is not useful for precise
>>>conversion.  I've found references to lots of commercial software that
>>>will do it, but I've never seen a formula to convert it.
>> 
>> What does V&H stand for? I've been around co-ordinate systems
>> for almost 20 years and that one doesn't ring a bell.

> I had no idea what this was initially either. It seems that the Vertical
> and Horizontal system was designed to convert physical measurments on a 
> curved globe to rectilinear measurements on a flat map. So a 
> degrees/minutes/seconds latitude/longitude coordinate would be converted
> to actual distances in meters or feet.
> It seems to be pretty complicated math. Two systems are used for V&H: 
> NAD-27 and NAD-83. NAD-83 is metric.

NAD-etc are datums and are not projections.

> V&H is commonly used in telecom, apparently.

Not around here (that I know of). I've worked in Telecom and GIS
here and have never come across anything other than the local
co-ordinate system, which...

> Here is one calculator, but it doesn't go in the direction Ralph needs:
> http://www.ngs.noaa.gov/cgi-bin/utm_getut.prl

... around is usually UTM (universal transverse mercator) which is a series
of cylinders placed at uniform places on the globe to form regions. We're
in zone 18 in Ottawa.

> If anyone else wants to try, this is exactly what I typed into Google:
> "vertical and horizontal" coordinates convert to latitude

There are literally dozens of co-ordinate systems in use.
Pick up a GPS receiver and go into setup mode to see the list
they support.
Many states in the U.S. use their own state plane projections for example
rather than the UTM grids. I've done projects with a few of the baby-bells
in the states and had to convert from their state plane systems to lat/long
for use in locating facilities on government map data.