This is from Trimble RTX....print out shows a Z value of 3892968.835m, and the El. Height of 141.832m....my question (being I haven't had to do this since the 80's or whenever....how do I create an elevation from this info....thanks...
rberry5886, post: 425750, member: 232 wrote: This is from Trimble RTX....print out shows a Z value of 3892968.835m, and the El. Height of 141.832m....my question (being I haven't had to do this since the 80's or whenever....how do I create an elevation from this info....thanks...
First of all, the Z value is part of the triplet of earth-centered earth-fixed defining the point's location with respect to the origin of the system. The origin being the center of mass including the oceans and atmosphere. We use the triplet to determine a latitude, longitude and ellipsoid height. NOT the Z-coordinate only.
If you have a point clearly labeled as an ellipsoid height and you know the system to which it refers, you use the ellipsoid- geoid separation to derive an orthometric height (like NAVD88).
An NAD83(2011) ellipsoid height can be combined with the output of the GEOID12B tool on the NGS web site to compute an orthometric height compatible with NAVD88. If the ellipsoid height is IGS08 you cannot use GEOID12B. You can use the output of USGG12B. If it is labeled WGS84, determine the associated GPS week, the most recent version of WGS84 is consistent at the few centimeter level with IGS09.
The relationship between ellipsoid (h), geoid (N) and orthometric(H) heights is: h - H - N = 0 + errors in h, H and N.
When you submitted to RTX did you ask for the results in NAD83(2011)?
Typically you would have the appropriate Geoid model (ie/Geoid 12B) loaded in your data collector. The geoid seperation from the model is applied to the Ellipsoid Ht by the collector to yield orthometric elevation (NAVD88 in the continental US) .
Yes, Yes, and Yes......