Questions tagged [geoid]
The hypothetical, natural, surface of mean sea level for the whole Earth. An equipotential gravitational surface. The datum for orthometric heights.
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Mapping older MSA definition to new codes
I have an old dataset that uses msa codes that are four digits and go from 40 to 9999. I would like to match it with the current downloadable data from the Census which has fips codes that are 5 ...
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Bilinear interpolation of a matrix to extract Z at different locations [R]
I have that geoid heights (quasi-geoid model hBG18) in a form that matrix :
library(tidyverse)
Geo <- read.table("https://www.isgeoid.polimi.it/Geoid/Europe/Belgium/public/hBG18.dat",
...
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EGM96 5' geoid model .tif file
Where can I find a .tif file of the EGM96 geoid height above the WGS84 ellipsoid with 5' resolution ?
I am working on converting vertical datum on different kind of files from WGS84 to EGM96 and surch ...
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Convert XYZ file with WGS84 Ellipsoid elevations to EGM96 Geoid elevations
I have multiple files in XYZ format in UTM horizontal + WGS84 ellipsoid vertical that I need to convert to UTM horizontal EGM96 geoid elevations. There are about 250'000 points in a an area that is ...
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Vertical transformation in ArcGIS Pro
I recently bought a drone with a LiDAR sensor that collects and exports an .las file in GRS80, there are no options to collect in other geoids. All of the jobs I work on or will work on are based on ...
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Convert ERA5 data on zero degree level into meters above sea level
I am trying to calculate the zero-degree isotherm (altitude in which temperature is at 0 degrees) in meters above sea level. I used ERA5 data by ECMWF for this and I noticed that the values decrease ...
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Recording GEOID altitude instead of ellipsoid
The Trimble receiver is capable of outputting the geoidal height. But for the whole thing to work, I have to do the conversion with Qfield. so far so good - the display shows the correct altitude. I ...
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Vertical datum transformation in ArcGIS Pro
I'd like to compare USGS 3DEP DEM with SRTM DEM for western U.S.. I did some research here, and find out that I need to match their datum (from NAD83-NAVD 88 to WGS84-EGM 96) before comparing the ...
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Which height data is correct? [closed]
I own the following device - https://interrex-tracking.com/lego-small/
the device is attached to a bird, and every day I receive information about time and date, X and Y locations, altitudе and geoid ...
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Calculate orthometric height with geoid ITRF97 and ellipsoid WGS84
I'm trying to calculate the orthometric height between ITRF97(or EGM96) and wgs84 (or grs80) in specific latitudes and longitudes.
For example:
in longitude 57.111 and latitude -5.582 i used an online ...
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What is the right geoid for calculating current sea depth from ECEF position and sea depth soundings
Let's say that I have an ECEF position (derived from GNSS, IMU, and barometric data) which is accurate to +-10cm. Let's also say that I have a chart of sea floor soundings, which, as unrealistic as it ...
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Are latitudes -90 and +90 both valid in WGS84?
Geometrically, I understand that a sphere can be addressed in latitude and longitude on the ranges [-90, +90] and (-inf, +inf) respectively.
However, I am working on the specification for plus codes, ...
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Three different distance values, which one should I use?
I'm implementing a script that (ideally) has a threshold of <1 meter. However, I have three different distances being pulled from these points that differ by multiple meters. I was wondering which ...
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Why measure height relative to geoid instead of ellipsoid?
Why do we measure elevation relative to sea level? I understand that water settles to a level surface, but why not just measure relative to an ellipsoid and dodge all the sea level rising, geoid, and ...
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What's this 8 byte "padding" in the EGM2008 data?
I recently downloaded the 1' earth gravitational model 2008 Und_min1x1_egm2008_isw=82_WGS84_TideFree dataset from here. According to the readme, the file consists of 233,301,600 32-bit floating point ...
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Calculating Geoid Height (e.g. EGM2008) for Lat/Lon in PostGIS
Is there an existing method or best practice for calculating Geoid height for a lat/lon location in PostGIS? I don't believe there is an "ST_" function.
I know that PostGIS makes use of ...
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Convert ellipsoid height to geoid using SpatiaLite
I would like to convert ellipsoid height to geoid (EGM2008) using SpatiaLite. is there any query that we could achieve this?
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Gravity related height from ellipsoidal height using pyproj
I'm using the pyproj library (http://pyproj4.github.io/pyproj/stable/index.html) to get translate ellipsoidal heights into gravity related height.
Code:
from pyproj import CRS
from pyproj import ...
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Can QField record GPS Z-Value
We are a land survey company and are considering using QField to perform asset surveys for local government agencies.
Looking through the documentation it appears that QField can do most of what we ...
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WGS84 to MSL and opposite
I am using CesiumJS to create point in a map using World Terrain to get the elevation of my points.
The point in Cesium are using WSG84. When I calculate the altitude using sampleTerrain I retrieve ...
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Transform datum CSV->CSV using ogr2ogr
First I have a set of points in UTM 48S / WGS84 (EPSG 32748) as test.csv:
X,Y,Z
9231824.04,787648.04,711.1442
Second I defined a test.vrt for ogr2ogr to read the data as follows
<...
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Understanding Google Earth Pro ruler tool algorithms?
When using Google Earth Pro ruler (Tools / Ruler or by clicking on the "ruler" icon), the ruler tool tells us the heading from one point to another which is not the same as that obtained by Karney's ...
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Where does the Geoid information in a GPS unit come from?
In the NMEA GGA-message the 11th field is Geoid separation. How does the GPS-unit "know" this separation?
Are GPS units preloaded with an EGM (Earth Gravitational Model)?
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Using NAVD88 geoid in Northern Canada?
The USGS NED (1-arcsec) dataset is available for the continental US as well as most of Canada. It is based on the NAVD88 vertical datum.
I am interested in using the DEM to orthorectify SAR scenes in ...
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Adding local geoid in ArcGIS Desktop?
My vector data is based on EGM2008 and I want to add local geoid to arcgis and project vector data from EGM2008 to local geoid.
If it is not possible to add custom local geoid in arcgis, how can I ...
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Adding GDA2020 NTv2 transformation to ArcGIS 10.5
The implementation of GDA2020 is drawing near! In an effort to be ready before time I have downloaded the NTv2 Grid Shift Binary (GSB) transformation grid from ISCM (available here) who are the ...
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What surface's area is used to compute area of country? [closed]
Premise:
Earth's surface geometry is modelled by means of different geoids -depending on the objectives. The roughest and most basic are ellipsoids surfaces. Yet, on a small scale, e.g., area of ...
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Using local mean sea level (LMSL) as altitude for converting latitude longitude altitude to ECEF
I am new in Geographic area and would like to convert latitude and longitude coordinates into ECEF x,y coordinates so that I could do some linear calculation of line or circle equation. I was able to ...
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How to calculate the distance to the Earth center if I know the elevation above the reference geoid?
How could I calculate this? Should I simply add it to 6371km?
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Seeking Trimble GGF Geoid File Format Specification?
I want to generate Trimble GGF Geoid files from my software.
Can anyone provide me with a format specification for the binary ggf files used by Trimble?
I found a basic description on the ...
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Downloading geoid chgeo2004?
Does anyone know where I could download geoids? Specifically I need the Swiss Geoid CHGeo2004.
I found this link: https://opendata.swiss/de/dataset/geoidmodell-chgeo2004-in-ch19031
But it only ...
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Converting elevation from EU-DEM (ETRS89) to WGS84
I'm having a hard time trying to use elevation data from EU-DEM.
This data is in ETRS89 (EPSG:4258), according to their site.
Now, when I extract the elevation for a shore, I get 0 meters of ...
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Convert Geoid File Types
Anyone know what I can use to convert a geoid surface stored as , BYN into .GTX for use with PROJ4?
The CCG2013A vertical datum and geoid model from NRCan is only available, as far as I can find, in ...
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Converting LiDAR ellipsoidal heights to orthometric heights?
Is there any tool to convert all Z attributes (ellipsoid h) value into orthometric height (H)? The idea is, having a point cloud (.las) and geoid undulation EGM08 (.asc) get a point cloud (.las) with ...
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Correcting incorrect altitudes of points recorded by my Android or how to calculate Geoid Height in QGIS
I tried to edit my question with more details and I also think that lot of people can benefit from this question!
I was recording a track with my Android and later I found out that I end up having ...
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What is elevation relative to in EPSG:2284?
I have some locations in EPSG:2284:
(3669486.63386,11293013.10592,709.08004),
(3669559.13811,11292972.72831,711.60055),
(3669639.51308,11292851.48264,712.22258),
(3669800.62304,11292949.38118,714....
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Are LiDAR datasets with same vertical datum, but based on different geoids comparable?
I have two sets of LiDAR for the same region that I would like to compare. Both are in NAVD88. The older LiDAR set used GEOID03 for the transformation. The newer LiDAR set used GEOID09 for the ...
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How does Ellipsoidal Height and Geoidal Height impact water flow? [closed]
I see this as a common theme
Ellipsoidal height doesn't dictate water flow.
Take a shot at explaining this. I think I understand this but it sounds like it would be of use to have a question about ...
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How does a Spatial Reference System change the underlying geoid without having to update coordinates?
Reading Wikipedia on WGS84 I see this,
Currently, WGS 84 uses the EGM96 (Earth Gravitational Model 1996) geoid, revised in 2004. This geoid defines the nominal sea level surface by means of a ...
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How does a Spatial Reference System like WGS84 have an elipsoid and a geoid?
I found out that WGS84 is an ellipsoid with a "geoid component", but I'm unsure exactly how that can be. This is from PostGIS in Action, Second Edition (pg. 64), but it seemed a bit vague.
...
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What is Considered in Geoid?
I found contradictory sources for what's considered in geoid and can't decide on either side because the sources seem about equally reliable. In particular, the question I'm asking is whether ...
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Vertical Datum conversion of a raster with gdal
Is there a tool available in gdal to do vertical datum conversion of a raster DEM? I'm looking for a single command line to execute the vertical datum conversion of a raster like the las2las of Liblas ...
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What geoid does WGS 72 use?
I see from the WGS Wikipedia article:
Currently, WGS 84 uses the EGM96 (Earth Gravitational Model 1996) geoid, revised in 2004.
I see there is an older EGM84 geoid but I couldn't find anything ...
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Find gravity normal by ECEF or GPS coordinate of point
How to find gravity normal by ECEF or GPS coordinate of point?
Is it the same as normal to elipsoid?
Is this ordinary way to calculate normal to ellipse?
I'm not quite sure which altitude is GPS ...
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How to georeference city data set with geoid and objectid as only location data
I am new to Cartodb and ran into my first hiccup. I was trying to import a data set of walkable food access in Philadelphia that is available from Open Data Philly. I can't figure out how to ...
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How to convert the SRTM DEM orthometric to ellipsoidal heights using ArcGIS or others GIS?
Recently I got the SRTM DEM from Cgiar,which based on WGS84/EGM96.
and I merged the tiles to one tiff file. I want to get the WGS84 ellipsoidal heights.
According the steps from the Arcgis Help 10.2 ...
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How can I calculate the intersection of a line and the geoid (EGM96)? [closed]
I have a known line (point and vector) described in ECEF (Earth-Centered, Earth-Fixed) coordinates and I need to find where it intersects the geoid (Earth Gravitational Model 1996). Is there existing ...
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Is there a method to tell which hemisphere a point belongs to, in WGS84 geoid, where the equator is an arbitrary ellipsis?
I use the WGS84 geoid (because I'm working with a GPS chip).
I define an ellipsis that splits the surface in two parts, lets name these 'A' and 'B'.
This ellipsis is defined by two points 'a' and 'b'...
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What programs would allow for the mapping of a geoid in 3d?
I would like to find a method for plotting an exaggerated geoid (e.g. topography):
I primarily use R for my work but would be interested in other open source software options (e.g. QGIS w/ GRASS). I ...
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How do you convert SRTM HGT elevations from WGS84 into meters above sea level?
I am building a JavaScript script that reads binary HGT files - as generated by the SRTM - and converts the data into bitmaps viewable in your browser.
You can try out the script and view the source ...
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