Geographic co-ordinates program

Any required transformations would be done once, before analysis. The equatrions required require only simple arithmetic. This required using the inverse or forward projection equations for every point. If you need to put data sets from a different projection on the map, say a SPCS system on a UTM map, the required actions would look like this:.

Coordinates Action, map to data top to bottom Action, data to map bottom to top Screen Coordinates Simple transformation move origin, rescale Projected map coordinates, like UTM Inverse projection equations x,y to lat, long Simple transformation move origin, rescale Geographic map coordinates Second projection forward equations lat,long to x,y Projection forward equations lat,long to x,y Second projection projected map coordinates, Like SPCS Second projection Inverse equations x,y to lat, long.

As computers got faster, the cost of performing the transformations grew less, and currently is essentially negligible. The requriment to reproject data before it could be used became a bother for users, and led to having to have copies of particular data sets in each projection a user wanted to use.

I then quickly converted the data to DD. Computer software will convert coordinates from DMS to DD on a regular basis without us even knowing it is happening.

However, it's good to know the equation and I routinely see spreadsheets of data in DMS and I can quickly convert the data to DD because I know the following information.

Converting between DD and DMS is now easy with the one addition that we need to remember that latitudes in the southern hemisphere are negative while longitudes in the western hemisphere where most of the US is are negative. We almost always need spatial data to be in Decimal Degrees in order to work with it in a computer.

Here are some examples:. The precision of geographic coordinates varies based on how they are formatted and regularly see coordinates in DMS with just the degrees without a decimal or minutes after them. The degrees are only precise to about km so the coordinates are basically worthless. Use the information below to quickly compute how many digits you need to retain in DMS for the required precision:.

Didn't find what you are looking for? We've been online since and have created 's of pages. Search below and you may find just what you are looking for. Michael R. We created the first U.

Learn more about us and our services. Have a project in mind?