Questions tagged [datum]

The information connecting numerical coordinates to actual locations on the earth.

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27 views

get “Cannot find coordinate operations” in GDAL 3; works in GDAL 2

I get the following error when trying to use GDAL 3.1.2 for computing the LLA from my custom gnomonic projections. Am I setting it up wrong? Missing some information/files? Would it be a misconfigured ...
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6 views

Converting GEOID18 elevation data to NAVD88

Is there a way to convert vertical data from GEOID18 to NAVD88 (survey feet) (EPSG:6360)? . Horizontal coordinates in NAD83-2011-EPSG:6570.
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33 views

How to convert elevation data from Google Elevation API to NAVD 88?

I want to convert the elevation data obtained from Google elevation API to NAVD 88. I understand that Google uses WGS84 with EGM96 Geoid. Do you know what I should do to convert the elevation data? ...
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Datum transformation in QGIS Server 3.10

I have a QGIS project that uses data stored in Web Mercator (epsg:3857) spatial reference system. The project itself has epsg:5514. To have a better precision I use one of datum transformations that ...
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137 views

What is MHHW Mean Highest High Water, in terms of datums/coordinate systems?

I'm modeling sea level rise, which entails adding the projected sea level rise for a specific decade to the current MHHW height (I think. I am new to this.) My question is very general--what is MHHW ...
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15 views

Convert MHHW (mean highest high water) to WGS84, or NAVD88

I am trying to create a tidal surface to use in mapping sea level rise. My first step was to create a raster surface from points in ArcGIS. I then used VDatum from NOAA to transform that surface from ...
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59 views

Conversion of EGM96 to NAVD88

I am new to ArcGIS and geoids/ellipsoids, and I want to convert a dataset in EGM96 (the USGS SRTM DEMs) to NAVD88. I have the SRTM dataset from NASA downloaded and open in ArcGIS as .hgt files. I ...
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45 views

Datum Transformation from WGS84 UTM Zone 35N to ED50UTM Zone 35N with a grid shift file (.gsb file)

I would like to transform WGS84 UTM Zone 35N coordinates to ED50UTM Zone 35N coordinates with a grid shift file (.gsb file I have) in python using pyproj. I tried below code but it gives failed to ...
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45 views

Geographic Transformations in QGIS 3.12

I have a problem with the way that QGIS handles transformation parameters between coordinate systems based on the Datum NAD27 and those based on the Datum WGS84. In version 3.12.1 I have found that ...
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26 views

Reproject WKID Using DotSpatial

I am trying to use DotSpatial's ReprojectPoint code to transform between WGS84 and NAD83(2011). This done for some spatial validation (Comparing collected data to NGS Monument Data) project I am ...
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26 views

Aligning different vector features and vector features with rasters

I am fairly new to GIS and I encountered this problem concerning projections. Maps don't align despite having the same projections (according to the Properties - XY Coordinates). I already tried with ...
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Why there is a different relative to Geodetic Azimuth from Arc Map from the original datums and transformations?

We where conducting a displacement for some BM (Old vs New values), we made calculations on different platforms for the North, East, Elevations. We used the NGS NCAT, Inverse 3D, TBC and manual ...
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101 views

Difference between datum transformations in QGIS 3.4 and ArcMap 10.7

Could someone briefly explain the difference between how datum transformations are handled by QGIS versus ArcMap? For example, I am under the impression that in QGIS you can simply select a ...
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1answer
190 views

Path to add NTv2 transformation to QGIS

Every time I start a new QGIS project, I have to add the BETA2007.gsb NTv2 Transformation. I would like to modify my QGIS settings in a way, that the NTv2 is automatically added to the project. When ...
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35 views

Why is my “choose crs” window grayed out when trying to choose a CRS for datum transformation

I want to choose a source and target CRS for datum transformation but when I click on the "choose crs" button, the window to choose the CRS is grayed out (see Image). I can think of a workaround but I ...
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1answer
112 views

What is the meaning of “SI-D-48-Gauss_Kruger” projection used in an ESRI WKT string?

Recently I encountered the following WKT CRS definition from an ArcMap project: PROJCS["SI-D-48-Gauss_Kruger",GEOGCS["GCS_Bessel_1841",DATUM["D_Bessel_1841",SPHEROID["Bessel_1841",6377397.155,299....
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146 views

Reproject in QGIS doesn't work the way like in ArcGIS [closed]

Sometimes I get polygon data that digitizes buildings, but they are slightly displaced like in the following example However, when I use the ArcGIS Tool "Project" to project the layer from a ...
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1answer
62 views

Which ArcGIS 10.7 transformation to convert WGS84 data to Washington State Plane North?

A bulk of my GIS datasets reference Washington State Plane North FIPS 4601 (US Feet). Often I get data in WGS84 that I need to transform to FIPS 4601. Ten years or so I worked though many of the ...
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30 views

Identifying of Vertical Datum from Metadata

I have been working with the DEM of South Carolina and I am not able to see from the metadata what is the vertical of the DEM. How do I identify the vertical datum from the attached screenshot of ...
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47 views

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 ...
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64 views

Problems importing raster to GRASS from QGIS (error: Datum ETRS89)

When I try to import raster from QGIS to GRASS with r.in.gdal.qgis an error of projection appears. Raster is in EPSG::25831 - ETRS897UTM zone 31N and mapset is supposed to be defined with the same. ...
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62 views

Shapefile appears correct on QGIS, but wrong on Google Earth

I've created a shapefile on QGIS, drawing over a raster that I've just georeferenced. The raster is a map with UTM lines drawn every 50 meters, so it was easy to georeference. Moving the mouse over it ...
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100 views

Adequate proj4string for ETRS89

I am currently working with spatial data in R using sp When I used WGS84-referenced coordinates, I used to specify it by setting the proj4string to: +proj=utm +zone=18 +datum=WGS84 +units=m +no_defs +...
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34 views

How to run OSGeo4W shell for molodensky transform?

I'm a beginner with Proj, so I just downloaded proj, and I'm using the OSGeo4W Shell and when I try to run the example proj=molodensky a=6378160 rf=298.25 da=-23 df=-8.120449e-8 dx=-134 dy=-48 dz=...
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71 views

What are the standard values of the GPSMAPDATUM attribute in the exif standard?

I'm working on an application to read the exif georeferenced metadata of some photos. I would like to know all the possible values of the attribute GPSMapDAtum. Do you know where to find a list with ...
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161 views

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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1answer
47 views

Why are there differences in output position between the ArcGIS versus NCAT transformation [NAD83 to NAD83 HARN]?

My question is specifically referencing the file-based grid transformation methods that are now available in ArcGIS. I thought this grid-file method was exactly the same method that NGS's NCAT used ...
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41 views

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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1answer
100 views

NADCON 5.0 Transformations in ArcGIS

Are the new(ish) NADCON 5.0 transformations available in ArcGIS? If so, at what versions? If not, can they be added? Specifically, I am looking to go from NAD83(2011) to NAD27. I am ...
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62 views

Dynamic Text Datum properties in ArcMap

Is there a way to add the datum information to a layout using dynamic text in ArcMap. I am aware that the properties of the CRS can be added, including the datum name using but I am looking for the ...
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1answer
204 views

Convert IGLD85 to CGVD28 - Vertical Datums

I have water level data for the Toronto Harbour that states, "74.200 metres above IGLD 1985" I also have land elevation data around Toronto that uses the Geodetic Vertical Datum of 1928 (CGVD28) To ...
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1answer
119 views

Can we say ECEF datum like in Geodetic datum?

Commonly we use geodetic datum to describe the geoid, a distorted ellipsoid model of the Earth, but is it correct to say Earth-Centered Earth-Fixed (ECEF) datum? Because we are applying ECEF to a ...
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49 views

Transforming to GPS coordinates using projections with osgeo with Python

I am trying to transform a shapefile and its datum to GPS (EPSG Projection 4326 - WGS 84) but I get very different result on Google Earth, I write: from osgeo import ogr, osr file_name = 'POIS.shp' ...
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105 views

Create custom coordinate system

I have the following info from a data provider and need to create a custom coordinate system using these parameters. The end goals is to map a file in this coordinate system against other data sources ...
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73 views

What datums were used in North America before NAD27?

What datums were used in North America before NAD27? I googled around on this without luck. Also I found an old nautical chart of Lake Michigan, dated 1876, which states: Longitudes on this map ...
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120 views

ntv2 datum transformations-problem on file output

I am working with qgis 2.18.27 I have installed ntv2 datum transformations and it worked fine, but yesterday it didn't work and i am not finding the way to resolve the issue (explained below) I am ...
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1answer
380 views

How to apply a default datum transformation in an expression in QGIS

I'm using the expression: x(transform($geometry, 'EPSG:32632', 'EPSG:3003')) to add coordinates fields according to different CRS in a point layer. To obtain better accuracy i need to apply a Datum ...
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574 views

Translating WGS 84 datum to mean sea level?

I'm very new to GIS so here my question is I have WGS84 DEM data for my country and I want to calculate the sea level rise. I will use QGIS raster calculator, my problem is I need to find sea level ...
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1answer
104 views

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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Sentinel 1 (A and B) Vertical Datum

I have been working through the ASF's "Recipes" for the creation of a DSM from Sentinel 1 (A and B) imagery. I am able to produce a DSM, and am relatively happy with the results in terms of the ...
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2answers
5k views

What Datum is used by Google Maps?

I am trying to convert vector shapefiles into Google Maps Datum using QGIS. Do you know which one is the datum? When I tried to convert them into WGS84 EPSG 3857, I could see that the shapes of ...
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1answer
181 views

NAD83 to NAD83(CSRS) transformation for Northwest Territories, Canada

I am looking to determine the correct Grid Shift Binary (gsb) file for transforming data from the NAD83 original to NAD83(CSRS) geodetic datum for the NWT in Canada. I was able to find reference for a ...
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342 views

What is the formula to convert geodetic coordinates to state plane?

I know there are tools that can do the conversion like pyproj, but I'm actually interested in the formula for computing it. Or if it's done with a big lookup table. I would love some information on ...
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716 views

Defining Latitude and Longitude before defining Datum?

Reference material: The Five Key Ingredients for Mapping the Earth There are five important steps to producing a map of the Earth's Surface. These are: sphere with north and south through the ...
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1answer
581 views

Datum transformation in QGIS 3

I have an Esri shapefile with following in the .prj file (broken into multiple lines for comprehension): PROJCS[ "SGL_Stereo", GEOGCS[ "GCS_SGL_GEO", DATUM[ "D_SGL", SPHEROID["...
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1answer
265 views

Pix4D and ODM generated tiff with same source images not aligning?

I have created two georeferenced orthomosaics using dronemade images. I used OpenDroneMap and Pix4D for that and I used the same source images for both. I thought that if I used the same images, the ...
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335 views

How to change the vertical datum of a geotiff DEM

I am trying to do some change detection between SFM derived DEM products, but the DEM i would like to use as my base elevation (and one other) is in NAD83, the remainder are WGS84. I would like to ...
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74 views

Missing datum only have lat long

I have some lat long coordinates but do not have any other information (datum, CRS etc) . I know where the place on Earth is but I cannot locate it (is a few miles off) using the coordinate numbers I ...
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1answer
360 views

Trimble 7X GNSS point Z returns negative elevations

I have a newly acquired Trimble 7X (with a centimeter kit). I collected a point in an area with a clear view of the sky. The accuracy indicator showed 1" accuracy and post processing and a ...
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1answer
69 views

Universal Datum Transformations between Rasters in ArcPy

Problem: Translating a set of various rasters with different datum into the same datum using ArcPy My Solution: Run rasters through a for loop, check their datum with an 'if' statement, run rasters ...

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