The geodesy tag has no wiki summary.
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0answers
20 views
How do I account for changing latitude with a spatial filter?
I'm working with data in latitude/longitude grid form in a non-GIS specialised package (MATLAB) and wish to apply spatial filters to it.
As this data contains a broad range of latitudes and is ...
-1
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0answers
27 views
Question on Geodesy [duplicate]
How important is it to understand geodesy when dealing with GIS? Also does anyone have recommendations on learning more about geodesy?
7
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1answer
93 views
Which training courses in Geodetics can you recommend?
Can anyone recommend any training courses in geodesy which would cover the following objectives:
Case studies on coordinate issues
Overview of geodetic datums, coordinate reference systems and ...
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 ...
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0answers
50 views
How accurate is spherical geodesic distance? [duplicate]
Possible Duplicate:
Approximating earth as sphere
We are in a situation where spherical distance computations may be more convenient and faster than ellipsoidal ones. However, I am ...
3
votes
1answer
145 views
Trilateration on a Sphere given 2 points and 3 distances
Given the points:
A) N 38° 38.000 W 90° 20.000
B) N 38° 39.000 W 90° 21.000
I can calculate the distance between the 2 using a spherical earth model as 7710 feet.
Given this segment and 2 other ...
2
votes
1answer
137 views
Trilateration in 3D with signal strengths
I'm having a hard time getting my head around the maths to locate a target in 3D given a number of known points (4 or more) and a value that indicates the signal strength (range 0–100).
I've looked ...
6
votes
3answers
312 views
How to generate geodesic linestring from two points in C#
I'm looking for a FREE C# class, library or set of functions that will allow me to generate a geodesic linestring (or array of vertices, whatever) from two decimal degree points.
I've found ...
1
vote
1answer
74 views
Which SRS is computational more effective to store continental scale data? (given some conditions)
For a Precision Agriculture application I need to make calculations in UTM projection. The data will be stored in Postgis and is made of soil samples results (point data) and field boundaries of many ...
1
vote
1answer
228 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.
4
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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 ...
8
votes
2answers
2k views
How do you compute the earth's radius at a given geodetic latitude?
(I see there is an equation on wikipedia that does exactly what I am asking but there is no references. I have no way of confirming the validity of this equation!)
I already understand the difference ...
2
votes
1answer
127 views
Attributes that characterize a geodetic track
I need a way to index and retrieve a large amount of track data. To do this I need to derive from every track as many attributes as I can. For now, I derive
Name
Tortuosity
Speed (average, max)
...
12
votes
2answers
374 views
How do you find a lat/lon (DMS) on a paper map using a 30cm ruler?
How do you use a 30cm ruler to find DMS on a paper map? The locations I would like to find are the 'corner' points so I can generate an extent based on the four corners.
I have an old paper map (3 ...
2
votes
3answers
1k views
How to perform trilateration using 3 lat/lon points without distances?
I read this thread Trilateration using 3 latitude and longitude points, and 3 distances explaining about trilateration using 3 latitude and longitude with measured distance.
The problem is I want to ...
8
votes
1answer
113 views
Is there a geodetic benchmark that is fixed with respect to plate tectonics?
I see that NGS benchmarks are used to monitor the movement of geologic plates.
Is one of the benchmarks assumed to be in a fixed location, with movements of all other benchmarks measured with respect ...
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5answers
5k views
Trilateration using 3 latitude and longitude points, and 3 distances
I want to find out an unknown target location (latitude and longitude co-ordinates). There are 3 known points (latitude and longitude co-ordinate pairs) and for each point a distance in kilometers to ...
