Questions tagged [datum]
The information connecting numerical coordinates to actual locations on the earth.
249
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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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157
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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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1
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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 ...
2
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1
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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 ...
4
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1
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944
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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 ...
2
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1
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286
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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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474
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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
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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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168
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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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803
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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 ...
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160
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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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201
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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 ...
2
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2
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1k
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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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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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458
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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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417
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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
<...
3
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1
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128
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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
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51
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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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1
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302
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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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1
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114
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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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957
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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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601
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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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1
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101
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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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1
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267
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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
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274
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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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221
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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
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1
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902
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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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4k
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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 ...
6
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300
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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 ...
2
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0
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85
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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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2
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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 ...
5
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1
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641
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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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2k
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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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1k
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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
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1
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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
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1
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431
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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
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0
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712
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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 ...
2
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0
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82
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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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1k
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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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108
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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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388
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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 ...
4
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2
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312
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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
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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 ...
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1
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1k
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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 ...
3
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2
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3k
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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?
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66
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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 ...
3
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668
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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 ...
3
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1
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1k
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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
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2
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119
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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 ...
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149
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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):...