7

Convert from (EGM96) geoid vertical datum to (WGS84) ellipsoid vertical datum: gdalwarp -s_srs "+proj=longlat +datum=WGS84 +no_defs +geoidgrids=egm96_15.gtx" -t_srs "+proj=longlat +datum=WGS84 +no_def" dem_in_egm96_geoid.tif dem_in_wgs84_ellipsoid.tif You will need the gtx file containing vertical datum shifts from here: http://download....


6

EPSG has added it as 6647. At Esri, I have it in a development build, but it's not in ArcGIS 10.3 (hopefully 10.3.1). Here's the Esri WKT for it: VERTCS["CGVD2013_height",VDATUM["Canadian_Geodetic_Vertical_Datum_of_2013"],PARAMETER["Vertical_Shift",0.0],PARAMETER["Direction",1.0],UNIT["Meter",1.0],AUTHORITY["EPSG",6647]] This document on height ...


6

No, when doing a map projection, the vertical coordinates are unaffected. If you look at the math behind a map projection (cf. Snyder's Map Projections: A Working Manual). you'll see that there's no mention of any vertical data. The only time you might see altitude or elevation mentioned is if the projection allows you to set its perspective point like ...


5

NTv2 is a raster format, which you can read with GDAL and related tools. You may want to organise your gridshift files in PROJ_LIB. (E.g. on my Windows computer this is C:\OSGeo4W64\share\proj). You can get individual extents from files with gdalinfo BWTA2017.gsb, or if you have rasterio: $ rio bounds BWTA2017.gsb {"bbox": [7.482986111111111, 47....


5

This will be possible with the Project tool with ArcGIS 10.4 (already available as pre-release). An additional parameter 'Vertical' allows you to specify an input and output vertical coordinate system, in addition to the horizontal coordinate system: This new parameter is mentioned in this What's new in 10.4 document (without much detail).


5

The offset that you have between your bathymetry and your elevation model relates to the difference between the Mean Seal Level (MSL) and the Lowest Astronomical Tide (LAT). From the well written text found here we can read that: The MSL surface is in a state of gravitational equilibrium. It can be regarded as extending under the continents and is a ...


4

This answer isn't a single command, but I'll put it in to get the ball rolling. Use gdalwarp to resample the geoid grid, then gdal_calc.py to shift the original raster. gdalwarp -s_srs epsg:4326 -t_srs epsg:26910 -r cubic -tr 10 10 -tap HT2_0.gtx HT2_0_resampled.tif gdal_calc.py -A original.tif -B HT2_0_resampled.tif --calc="A+B" --outfile=shifted.tif If ...


4

If you are doing vertical conversions over the ocean you really need to use VDatum. Vdatum runs a detailed, unstructured mesh tidal model (ADCIRC model, usually), then computes tidal coefficients, generates an 18.6 year time series, then determines surfaces of MLW, MLLW, MHL, MHHW, etc. These surfaces are then evaluated at known tidal gauge locations, and ...


4

Your data is in a compound coordinate system; i.e. vertical data in one coordinate system and horizontal in another. This is true both before and after transforming the raster to EGM96-relative heights. The horizontal (XY) coordinate system can be anything you choose - though typically one would select a map projection tailored to the area of interest (...


3

ArcGIS doesn't support GEOID03 yet as of ArcGIS Desktop 10.6.1 and ArcGIS Pro 2.2. Some possible workarounds... Convert GEOID03 into a raster format supported by ArcGIS and use raster calculations to convert the z (cell) values into ellipsoid heights. Redefine the raster's vertical coordinate system to NAD83 (which one?) ellipsoid heights. Then convert ...


3

I didn't figure out how to make it work with the gdalwarp, but I downloaded VDatum and did a single point coversion. After which it identified that I needed to use the geoid12b. Then I found in the VDatum directory the geoid12b/*.gtx files. Opened the NED file in gdal and the geoid file in gdal and created a matching projection of the geoid into the NED and ...


2

A great tool that is often used for vertical datum transformations is called V-datum, developed by NOAA. This is the tool that I have seen cited most often for similar tasks with a range of different datums including tidal. The V-datum docs has some information, as well as this gis.stackexchange answer on EGM96. I'm not familiar with lowest astronomical ...


2

You can download a demo verion of the Hydromagic software from https://www.eye4software.com/download/ It includes a geoid converter freeware: https://www.eye4software.com/hydromagic/documentation/manual/utilities/geoid-file-conversion/ Supported file types are .geo, .ggf, .gsf, .byn, .bin, .grd, .txt, .gtx as source and destination. They offer a bunch of ...


2

The reconstruction will use the Z values from the image EXIF header as derived from the on-board GNSS unit. The resulting surface will be in WGS EGM96 as returned by the satellites.


2

There is two way to solve your problem: 1st you can try to use the EPSG code for the EGM2008 height with pyproj which is EPSG:3855 (instead of the NAD83 datum that you are trying to use because it is a horizontal datum and not a vertical datum) 2nd you use PROJ6 instead of pyproj (pyproj is the python library from proj) You need to use the proj ...


2

Perhaps the Scale Selected Items tool in OpenJUMP would be close to what you want. The tool shows the original bounding box of the selected features and user can drag one corner while the opposite corner is fixed. A ghost linework shows the preview of the result and when the mouse button is released the features are scaled. QGIS may have a similar tool but ...


2

I have found a plug in that is suitable for my demands but is not quite what I was looking for in first place The plugin is called "Vector Bender" which function as a vector georeferencer


1

From projinfo application of the PROJ library: c:\>projinfo -s EPSG:4979 -t EPSG:7417 returns: Operation n1: unknown id, Inverse of DVR90 height to ETRS89 + Inverse of ETRS89 to WGS 84 (1) + UTM zone 33N, unknown accuracy, Denmark - onshore, at least one grid missing PROJ string: +proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=...


1

The error in the Trimble Z values was a result of accepting the default geoid model inside of Trimble GPS Pathfinder Office during export. Doing a differential correction on the rover file and exporting the corrected rover file to an ESRI shapefile using geoid09 (conus) returned z values within the range of the LiDAR data and further refined those Z values ...


1

AUSGeoid2020 is only correct if your data is in GDA2020, which is an emerging standard not fully implemented, you most probably want AUSGeoid09 if your data is in GDA94, the transformation grid is available from Geoscience Australia ga.gov.au/ausgeoid. Geoid height is higher than AHD so find your value and add it to your Z value of your points and you ...


1

If you have a geoid model, that is often a set of equations to convert between gravity-related heights (elevations) and ellipsoidal heights. It's often modeled as a grid file. There are both versions for EGM96. A possible workflow would be: Convert Mongolian geoid/Baltic-based gravity-related heights to ellipsoidal heights. The geographic (latitude-...


1

Is there an issue with calculating the offsets in Northern Canada? Are the gtx files even defined there? If you open up the *.gtx files in QGIS, for example, you'll find that they are not defined north of about 58 degrees N. You will not be able to calculate geoid offsets outside of where the gtx file is defined. I don't know if you could possibly ...


1

GDAL will support BYN files in an upcoming release. However, it is unclear when this release will be compiled for windows. In the meantime, I've uploaded converted GTX files for HT2_0 and CGG2013 so that they are easily accessible until the GDAL capabilities come into effect.


1

See the direct function (dem_geoid) for geoid conversion available in the NASA Ames Stereo Pipeline(https://ti.arc.nasa.gov/tech/asr/groups/intelligent-robotics/ngt/stereo/).


1

I suggest to install proj-bin and proj-data from Ubuntugis unstable first. The large vdatum files can be downloaded from http://download.osgeo.org/proj/vdatum/ Put the files in /usr/share/proj/. In your file system, navigate to that folder, and open a terminal to execute sudo chmod 644 egm96_15.gtx or whatever grid file you want to use. Then you can ...


1

I asked which state in a comment because I wanted to check the dates for the HARN (High Accuracy Reference Network) and FBN (Federal Base Network) re-adjustments in California. According to GEOCON 2.0 doc, the original HARN re-adjustment was in 1992. The FBN (AKA HARN v2) was in 1998. This document, "AN EVALUATION OF THE HIGH ACCURACY REFERENCE NETWORK ...


1

Here is the answer I got back from NOAA. It's in the form of java code, and the order of parameters has to be inferred, but in case it proves useful to someone else here it is: public static final HTDP NAD83 = new HTDP(0.9910, -1.9072, -0.5129, 0, 0, 0, 1.25033e-7, 0.46785e-7, 0.56529e-7, 0.00258e-7, -0.03599e-7, -0.00153e-7, 0, 0, 1997); public static ...


1

If you have the Spatial Analyst extension you can use the Extract Values to Points tool to add the data from the raster to the point data. You could then use the field calculator to add the two values, either in an existing field or in a new one.


1

No GDAL cannot perform vertical transformations.


1

In Canada, see GPS-H from Canadian Geodetic Survey. As the name implies it's suitable for point records and not lines & polygons, and unlikely a good fit for mass points. Input formats are ascii text files like CSV. GPS-H allows conversion of GNSS ellipsoidal heights h, that are either in NAD83(CSRS) or ITRF, to orthometric heights H (heights above ...


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