# Longtitude and Latitude to Cartesian

• ### Question

• Hi Guys and girls i am Domino many thanks to the developers who have replied to my posts you have all been very helpfull, even the young developers that tried to help many thanks.

I have another question for the advanced developers, i have a set of British Longtitude and Latitude Coordinates and im trying to convert them to Cartesian can someone shed some light on this please with possibly some code to convert the bellow coordinates, i have a list of posts about 12 from other sites other developers trying to achieve the same outcome i will post your code on all the sites with your user name to help others. i am using VB-8 (Visual Studio 2005 Pro)

Latitude = 0.93858440528
Latitude = -0.05297033814

Many Thanks in advance

Domino

(MCSD, MVP)
Saturday, September 8, 2007 7:01 PM

• DominoVBCF,

Based on your post, you would like to convert the set of British Longitude and Latitude Coordinates to Cartesian. I notice that you have posted this problem in several forums as below:

Longtitude and Latitude to Cartesian

I would like to provide the related information on the issue and hope that can provide you some idea:

The 'quick and dirty' method (assuming the Earth is a perfect sphere):

x = longitude*60*1852*cos(latitude)
y = latitude*60*1852

Latitude and longitude must be in decimal degrees, x and y are in meters.
The origin of the xy-grid is the intersection of the 0-degree meridian and the equator, where x is positive East and y is positive North.

There is a mechanism called "rubbersheeting" whereby you take the x/y coordinates of several identifiable points on your map (like the Florida Keys or the mouth of the Mississippi). You then mathematically derive a formula to transform these x/y points to the well-known lat/longs. This gives you a rough formula to do the conversion - a short cut to the projection.

The reference I use for this stuff is: "Map Projections-A Working Manual" by John Snyder. This book is a guide to map projections and the underlying mathematics. It was published by the USGS and may be out of print.

Tuesday, September 11, 2007 7:54 AM
• I'd start here http://gps.ordnancesurvey.co.uk/convert.asp the general information link at the bottom of the page is very good.  The spreadsheet provides VBA code for most types of co-ordinate transformation.

Tuesday, September 11, 2007 8:50 AM

### All replies

• DominoVBCF,

Based on your post, you would like to convert the set of British Longitude and Latitude Coordinates to Cartesian. I notice that you have posted this problem in several forums as below:

Longtitude and Latitude to Cartesian

I would like to provide the related information on the issue and hope that can provide you some idea:

The 'quick and dirty' method (assuming the Earth is a perfect sphere):

x = longitude*60*1852*cos(latitude)
y = latitude*60*1852

Latitude and longitude must be in decimal degrees, x and y are in meters.
The origin of the xy-grid is the intersection of the 0-degree meridian and the equator, where x is positive East and y is positive North.

There is a mechanism called "rubbersheeting" whereby you take the x/y coordinates of several identifiable points on your map (like the Florida Keys or the mouth of the Mississippi). You then mathematically derive a formula to transform these x/y points to the well-known lat/longs. This gives you a rough formula to do the conversion - a short cut to the projection.

The reference I use for this stuff is: "Map Projections-A Working Manual" by John Snyder. This book is a guide to map projections and the underlying mathematics. It was published by the USGS and may be out of print.

Tuesday, September 11, 2007 7:54 AM
• I'd start here http://gps.ordnancesurvey.co.uk/convert.asp the general information link at the bottom of the page is very good.  The spreadsheet provides VBA code for most types of co-ordinate transformation.

Tuesday, September 11, 2007 8:50 AM