Questions tagged [geodesy]
Scientific discipline dealing with the measurement and representation of the Earth's shape and gravitational field.
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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 ...
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Re-referencing raster in rotated coordinate system by "de-rotating" it
My Trying to define a "rotated regular grid" coordinate system in QGIS question about this got closed because there was already an answer to it, which I understand. I went to the answer in ...
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How to find out if three points on Earth are on the same great circle?
I am trying to figure out whether 3 particular points on Earth's surface are on the same arc (of a great circle) or not. Using Google Earth's (also ArcGIS Earth's) line tool, I see that the points are ...
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Local System to Lat-Lon
I have a local system coordinates (Pi) of a satellite and I want to calculate observer latitude and longitude from the local coordinates of the satellite. I did this operation manually, I didn't use ...
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Meridian Convergence in UTM and Gauss Kruger Projection system?
There are points where geographic coordinates (latitude and longitude) are known. I have calculated the UTM (Universal Transverse Mercator) projection coordinates of these points and then I want to ...
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Calculate where a geodesic line crosses a meridian
Given a geodesic line between two points with known coordinates on a sphere, is there an easy way to calculate or approximate where this line crosses a specific meridian?
I want to calculate where ...
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How do you decide a new datum?
How do you decide datum size (axies a & b) and datum position relative to WGS84 (dx,dy,dz,rx,ry,rz) for a country if you were to create a new datum best fit for the country?
Example, is datum ...
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Completing Coordinate transformation?
I have two airborne lidar datasets and, for purposes of comparing change between the two, would like to standardize the vertical and horizontal coordinate information for each. The plan is to ...
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How to use pyproj to convert between ITRF2014 2023.9 to ITRF2014 2017.0
I am trying to convert a current observation from 2023.9 to a ITRF2014 2017.0 epoch. The Longitude Latitude is: -83.9851111, 43.9823026, 191.101. I Used pyproj to convert to ITRF2014 and then convert ...
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Converting geodetic coordinates to ENU coordinates
I am trying to understand conversion from geodetic coordinates to ENU coordinates. As per this wikipedia page, its two step process: geodetic to ECEF coordinates and then ECEF coordinates to ENU ...
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Calculating the surface area of the ocean at each latitude
I am trying to get the surface area of the ocean at each 1° latitude slice. However, for some unknown reason, region -61 which is at latitude -61 has a negative number, and am not sure why that is the ...
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Viewshed curvature of Earth using ArcGIS Pro
I've been running some viewshed analyses in ArcGIS Pro 2.5.0 and a few of these involve results at extreme ranges (200km+). This is set in a mountainous region with a few especially dominant features, ...
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Are there any naming conventions for heights (orthometric / above ellipsoid)?
We are used to lat and lon names for describing latitude and longitude on the WGS84 ellipsoid. But I cannot figure out a single convention for naming the ellipsoidal height. The most common way of ...
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Reverse Calculate Ellipsoidal Height
I have a few hundred points with ellipsoidal height taken a few years ago. Based on these ellipsoidal heights I had deduced orthometric heights for the same.
Is there a way to find the ellipsoidal ...
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Intersection between a ray from lat, lon, alt, with pan, tilt and earth's surface
I have a problem that consists of finding the intersection point between a ray from a given lat, lon, alt, that is looking to a given pan and tilt angles and the earth's surface. I need the lat, lon ...
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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 ...
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Geodetic to ENU conversion
I am trying out geodetic to enu conversion. I tried this pymap3d's geodetic2enu function:
import pymap3d as pm
lat0 = 37.7749 # deg
lon0 = -122.4194; # deg
h0 = 10.0 # meters
lat = 37.7750 # ...
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Does the ellipsoid intercept sea level markers?
I know the geoid represents the gravity surface as if mean sea level, but came across a comment that the geoid was created by taking the ellipsoid, setting the volume constant and changing that ...
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How can I calculate the course angle of two coordinates in decimal degrees?
I want to calculate course angle of two given decimal degrees, like shown in the following picture:
In the above picture the result would be 135°
The coordinates are given in decimal degrees, e.g. (...
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How to convert ITRF to ITRF
ITRF 96 1998.0 epoch
X Y Z Vx(m/y) Vy(m/y) Vz(m/y)
4059623.25 2764405.93 4056720.43 -0.0079 -0.0007 0.0132
Transformation parameters from ITRF1996 to ...