The ellipsoid tag has no wiki summary.
4
votes
2answers
1k views
What datum (reference ellipsoid) does Google Earth use?
What datum (reference ellipsoid) does Google Earth[1] use?
I can't seem to find where Google Earth tells explicitly what datum they use. I need some sort of valid link.
[1] The default free version ...
2
votes
2answers
847 views
How are EGM96 and WGS84 related to each other?
As far as I understand the EGM96 defines the Geoid, where as the WGS84 Standard defines the Ellipsoid.
Is the ellipsoid defined in the WGS84 standard defined in a way to maximize the congruency with ...
3
votes
0answers
102 views
Bearing/Course/Heading in WGS84 ellipsoid model
There is a common formula for computing the initial bearing for a course from lat1, lon1 to lat2, lon2. (And yes, I'm aware that the course will change when traveling).
atan2( sin(lon2-lon1) * ...
19
votes
2answers
290 views
Are ellipsoids a mathematical necessity?
The literature usually just tells us that the Geoid is complex to describe mathematically and that we therefore fit different Ellipsoids to approximate it.
Are these Ellipsoids mathematically ...
3
votes
1answer
93 views
How to determine error radius of given points
I am running QGIS 1.8.0 on a 64-bit Windows 7 platform.
Given multiple points with different (but close) coordinates, how do I automatically create a new point that programmatically takes into ...
2
votes
0answers
55 views
is ellipse inside ellipse in WGS84 ellipsoid
My question is quite clear:
Assume that there is an ellipse, namely EL1. Parameters of the ellipsoid are (focus11 [latitude, longitude], focus12[latitude, longitude], radius1).
And a second ellipse, ...
1
vote
1answer
38 views
How to fix PJ_healpix.c in PROJ.4?
Michael Speth and i are in the process of fixing the PROJ.4 implementation of the HEALPix map projection (see http://trac.osgeo.org/proj/browser/trunk/proj/src/PJ_healpix.c for the current buggy ...
3
votes
1answer
195 views
What is the DNSC08 Mean sea surface model ellipsoid based on?
Does anyone know what Danish Space centre DNSC08 mean sea surface model uses as the reference ellipsoid? there is no meta data on the web site:
...
7
votes
3answers
194 views
What's a term for Sea Level Distance which is usable by novice users?
I've been using the term Sea Level Distance to describe the total length of a line string where I ignore the elevation and just calculate the distance from point to point along the ellipsoid and sum ...
1
vote
1answer
226 views
What datum (reference ellipsoid) does Nasa Worldwind use?
What datum (reference ellipsoid) does Nasa Worldwind use?
I can't seem to find where Nasa Worldwind tells explicitly what datum they use. I need some sort of valid link.
8
votes
3answers
611 views
What kinds of line segments/edges require high accuracy in a true surface-of-the-ellipsoid representation?
I've been musing (and doing prototype coding) for a 'projection free' geographic codebase with your basic point, line & polygon primitives.
Rather than dealing with all the sacrifices that come ...
1
vote
0answers
114 views
How to get the height according to EGM96 for a point?
For a program I have to calculate the height according to EGM96. I found http://earth-info.nga.mil/GandG/wgs84/gravitymod/egm96/egm96.html - this site delivers files with parameters and a ...
6
votes
1answer
170 views
Accuracy of planimetric geometry vs. ellipsoidal model
I'm examining the two geospatial options for IBM's DB2 database. In particular I am interested in the accuracy between these two options and whether it's worth it (the more accurate representation ...
