7 Parameter Transformation

[+GEO*Trailblazer 1]

I am wondering about this one,a new line of thought .Can anyone eloborate on this subject?

 

WHEN ALL ELSE FAILS *GEOTRYAGAIN* http://www.msnusers.com/MissouriTrails

[Wild T2]

Most GPS receivers can be set to use quite a few different datums and are pre-programmed with the parameters needed to do the conversion.

 

The seven parameter transformation is for transforming coordinates from one datum to another using earth centered X Y Z coordinates.

 

The coordinate for the center of the earth is X=0, Y=0, & Z=0. The X-axis is in the plane of the equator and is oriented to the Greenwich Meridian. The Y-axis is also in the plane of the equator and is oriented 90 degrees from the X-axis. The Z-axis is perpendicular to the equator and passes through the poles.

 

See link for a sketch and conversion program.

http://www.ngs.noaa.gov/TOOLS/XYZ/xyz.html

 

Your GPS figures out where you are using the WGS-84 datum using these X Y Z coordinates. The GPS receiver then converts the X Y Z to latitude and longitude, UTM or whatever you have it set to.

 

If you want to use a different datum the GPS receiver applies three translations and three rotations on the X, Y, and Z axes with the final and seventh parameter being a scale factor.

[+GEO*Trailblazer 1]

You hit the nail on the head.I was just wondering if any body else had heard about it on this site.I called EROS data center here a few years ago and talked to Dr.Dru Smith about some things that I was working on and he had explained it to me then.I just had not seen anywhere, that it was being used except on the NASA projects.

http://nweb.pct.edu/homepage/staff/wsprinsk/coordinate_transformation/page40a.htm http://denali.gsfc.nasa.gov/sla/sla/srowton/file_dist.html

WHEN ALL ELSE FAILS *GEOTRYAGAIN* http://www.msnusers.com/MissouriTrails

 

[This message was edited by Trailblazer # 1 on February 21, 2003 at 08:38 PM.]

 

[This message was edited by Trailblazer # 1 on February 21, 2003 at 08:44 PM.]

[Kerry.]

I'm not sure what some are trying to say here but 3D, 7 parameter transformation sets (and all sorts of other transformation data sets for that matter) are used in everyday use by a wide range of every day people.

 

There's no magic it's just maths.

 

Cheers, Kerry.

 

I never get lost everybody keeps telling me where to go