Bug in the javadocs for VerticalTransform and ModifiedEarthGravitationalModel
-----------------------------------------------------------------------------
Key: GEOT-3813
URL: https://jira.codehaus.org/browse/GEOT-3813
Project: GeoTools
Issue Type: Bug
Components: docs, referencing3D
Affects Versions: 2.7.2
Environment: Using trunk of geotools. Affects all operating systems,
java versions, and hardware platforms.
Reporter: arichnad
Assignee: Jody Garnett
The javadocs for VerticalTransform and ModifiedEarthGravitationalModel
heightOffset state this:
Returns the value to add to a <cite>height above the ellipsoid</cite> in order
to get a <cite>height above the geoid</cite> for the specified geographic
coordinate.
I believe this is exactly the opposite. As you can see here:
http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/intpthel.html
WGS 84 Ellipsoid height = Orthometric height + EGM96 Geoid height
In other words, the javadocs should probably read this:
"Returns the value to add to a <cite>height above the geoid</cite> in order to
get a <cite>height above the ellipsoid</cite> for the specified geographic
coordinate."
Or this:
"Returns the value to subtract from a <cite>height above the ellipsoid</cite>
in order to get a <cite>height above the geoid</cite> for the specified
geographic coordinate."
But if I follow the javadocs's suggestion, I get a value that is very wrong.
Example:
Here is: 38.883,-77.106
The DTED0 HAE for here is: 56 meters
The DTED0 Height above Geoid for here is: 89 meters
The heightOffset is returning: -33 meters
So, I can take the HAE and subtract the heightOffset to get the height above
Geoid.
Or, I can take the height above geoid and add the heightOffset to get the HAE.
But I CANNOT take the HAE and ADD the heightOffset to get the height above
Geoid.
Also affects:
* Geotoolkit
* The rest of the VerticalTransform class (I see addition being used to convert
from HAE to Height above Geoid)
Thank you for your attention!
adrian
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
------------------------------------------------------------------------------
Get a FREE DOWNLOAD! and learn more about uberSVN rich system,
user administration capabilities and model configuration. Take
the hassle out of deploying and managing Subversion and the
tools developers use with it. http://p.sf.net/sfu/wandisco-d2d-2
_______________________________________________
Geotools-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/geotools-devel
