Questions tagged [datum]

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

Filter by
Sorted by
Tagged with
2
votes
1answer
71 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....
2
votes
1answer
81 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 ...
2
votes
1answer
27 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 ...
0
votes
0answers
28 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 ...
0
votes
0answers
25 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 ...
3
votes
0answers
38 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. ...
0
votes
0answers
54 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 ...
1
vote
2answers
50 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 +...
2
votes
0answers
21 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=...
0
votes
2answers
45 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 ...
1
vote
2answers
111 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 <...
2
votes
1answer
38 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 ...
2
votes
0answers
36 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 ...
1
vote
1answer
69 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 ...
0
votes
1answer
38 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 ...
0
votes
1answer
118 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 ...
1
vote
1answer
99 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 ...
1
vote
1answer
45 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' ...
0
votes
1answer
62 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 ...
3
votes
1answer
62 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 ...
0
votes
0answers
23 views

Correlation between varying bearings

Problem: The Bearing of point B from point A on one datum and projection varies from that on another datum and projection. Can a consistent correlation be established for the variation in the Bearings?...
0
votes
0answers
75 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 ...
3
votes
1answer
261 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 ...
0
votes
1answer
372 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 ...
4
votes
1answer
81 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 ...
2
votes
0answers
44 views

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 ...
0
votes
2answers
3k 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 ...
3
votes
1answer
154 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 ...
-1
votes
1answer
257 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 ...
4
votes
2answers
642 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 ...
2
votes
1answer
356 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["...
1
vote
1answer
236 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 ...
2
votes
0answers
265 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 ...
1
vote
0answers
70 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 ...
1
vote
1answer
271 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 ...
0
votes
1answer
64 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 ...
0
votes
1answer
224 views

Cannot assign custom projection to raster file in QGIS

I have a LiDAR data tile (raster file in GeoTIFF format) that is currently in WGS 84 (lat/long) geographic coordinate system. However, the data was collected in New Arc 1950 / UTM Zone 36 South ...
3
votes
2answers
94 views

Transforming Datum in Lat/Long to Projection in Feet

I am having issues projecting my csv file I have imported in lat/long to our state government-standard projection (EPSG 102121 NAD 1983 Michigan GeoRef (feet)), which is based on Oblique Mercator. ...
4
votes
2answers
807 views

Raster DEM vertical units are defined in meters, yet Arcmap displays them in feet

Background: I have received a single-band, 32-bit floating-point tif raster DEM, derived from a lidar project. The tif's XY coordinate system linear units are feet. Its vertical coordinate system ...
0
votes
1answer
431 views

How to map using more 'accurate' DATUM than WGS84? [closed]

WGS 84 is not very accurate as it is a compromise for the whole earth. Assuming theoretically I'm surveying using very accurate IMU and very accurate GPS (in WGS 84 of course). I think I'll get a ...
2
votes
2answers
1k views

Converting vertical datum from WGS84 to EGM96 in ArcGIS Desktop?

I am comparing two different Digital Elevation Models SRTM (Datum: EGM96) Cartosat (Datum: WGS84) How to convert WGS84 to EGM96 in ArcGIS Desktop?
1
vote
1answer
48 views

Is it acceptable to assume there will be no 'walk' in coordinates transformed back and forth between two datums?

Given that you use the same datum transformation, you should end up with the same coordinate regardless of how many times you convert between to datums. Is this a correct assumption? Is this ...
2
votes
0answers
244 views

Postgis st_transform precision

I am checking effects of reprojecting planar coordinates from one CRS to another and back, keeping the same DATUM, and I was trying to determine the cause of the loss of precision. I know that ...
2
votes
1answer
527 views

Transforming from NGVD29 to EGM96/WGS84?

I have this USGS reservoir elevation in NGVD29 datum and I want to transform it to WGS84 ellipsoid (SRTM 1 ArcSec DEM). How can I transform this point data (NGVD29) to EGM 96 or WGS84 ellipsoid so ...
2
votes
2answers
72 views

Trying to project a shapefile to line up with another shapefile?

I have two polygon shapefiles representing district boundaries: Districts1 and Districts2. They are supposed to represent the same geographical area and same district boundaries, but I realized that ...
1
vote
1answer
32 views

What (where) are elements that comprise WGS60 and FSHR1960?

Considering two 1960 geodetic ellipsoids (from this list), I've found the following parameters (from here): WGS60: World Geodetic System of 1960: 6378165.0, 298.3 FSHR1960: Fischer – 1960 (Mercury):...
2
votes
1answer
84 views

Calculating Datum Corrections to Overlay pre-NAD27 USGS Maps?

I am working with some older (ca. 1900) USGS Topographic Maps. These Raster maps are georeferenced with a CRS of NAD27 and poly projection (polyconic). However, they are offset and require easting/...
2
votes
2answers
2k views

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 ...
1
vote
1answer
78 views

What vertical datum for OpenDroneMap with no GCP

I am processing drone imagery with OpenDroneMap using a native Ubuntu installation of OpenDroneMap. I see the the LAS generated returns points in UTM for X and Y coordinates as stated in the ...
1
vote
1answer
260 views

NOAA vdatum GDAL Variable Paths for Linux Ubuntu

I want to do vertical datum conversions on geotiffs using NOAA vdatum The conversion status menu shows no progress and no conversion happens. I see that Microsoft Windows needs GDAL environmental ...