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

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NTv2 inverse transformation calculation process

NTv2 grid files are used to calculation latitude and longitude offsets for a datum transformation. In the forward calculation, bilinear interpolation is performed by using the four closest points. ...
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23 views

6 degree of freedom helmert transformation

I'm looking to do datum conversions for points with six degrees of freedom, that is, they are described by a heading, pitch, and roll in addition to their position information. I know how to convert ...
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13 views

gdaltransform returns ERROR 1: failed to load datum shift file

I'm trying to do a NAVD88 to WGS84 (G1674) conversion using gdal. I've installed gdal (on centos7) using sudo yum install gdal proj-epsg proj-nad and am trying to perform the conversion via: ...
3
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1answer
24 views

VDatum helmert transform parameters

I'm trying to use NOAA's VDatum to verify the NAVD88 -> WGS84 datum conversion in a c++ datum conversion library that I've written. The answers didn't agree, so I attempted to check a simple ITRF2008 ...
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24 views

QGIS x ArcGIS - Geoprocessing Vectors in Geographic Coordinate Systems [closed]

Is there a possibility of in future versions of QGIS, the software be able to geoprocess vectors (clip, buffer, intersection, etc.) in Geographic Coordinate System, and not only in UTM? In ArcGIS, ...
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2answers
74 views

Datum shift issue between OSGB1936 and WGS84

I have to work between OSGB1936 and WGS84 and BOTH of these data sets started out life as OSBG1936 BounaryLine data. I thought I was just at the end of a full revision of my master mapping until I ...
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2answers
146 views

Is WGS 84 datum, coordinate reference system, or both?

The background to this question is in Understanding difference between Coordinate System and Projection? There @mdsumner commented: WGS84 is not a cs, it's a datum. On a couple of places online ...
3
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1answer
52 views

Why does QGIS do an unintended datum shift to WGS84 in the map canvas

I'm a new QGIS user running 2.12 Lyon. I've encountered an issue with map canvas units and an unexpected and transparent datum transformation to WGS84. I need help figuring out if I've missed ...
4
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1answer
54 views

Datum and transformation error using ST_Transform in PostGIS, going from NAD83 to NAD27

I created a function in PostgreSQL to transform input coordinates using UTM Zone 12/13, with Datums NAD83 or NAD27, to the WYLAM projection. I had to manually create the entry for the proj4text ...
4
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1answer
56 views

WRF Spherical Earth to WGS 84

Weather Research Forcasting Model assumes a spherical earth model with a radius of 6370km. I'm looking to display the data onto the WGS-84 Ellipsoid model as that is the model my system uses for its ...
3
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2answers
64 views

How to re-project a shapefile to be compatible with another shapefile or raster?

I have a polygon shapefile and a raster. The shapefile and raster have different coordinate systems. Coordinate System for the shapefile: NAD_1983_UTM_Zone_19N WKID: 26919 Authority: EPSG ...
6
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3answers
127 views

Vertical datum query for coastal modeling

This may be very specific. I have a USGS derived DEM with a vertical datum of EGM96 from NASA satellite data. My Bathymetry uses a lowest astronomical tide datum. Has anybody come across this or ...
3
votes
1answer
128 views

Difference between datum and ellipsoid for geodetic coordinates?

Looking at the Wikipedia page for the North American Datum, it seems to imply that the datum is completely defined by the ellipsoid, which defines the major/semi-major axes, flattening, etc. For ...
11
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1answer
690 views

why does the North American Datum not actually include north america in it's boundary?

http://spatialreference.org/ref/epsg/4269/ That link shows the area that the North American Datum 1983 covers and one thing I note is that it doesn't cover North America. It covers all of Asia and ...
0
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0answers
22 views

Valid Range of Geoidal Separation in GNS and GGA sentences

I haven't seen any information about valid ranges of geoidal separation in GGA and GNS sentences. I am using Nema Studio Simulator to simulate GPS receiver. In there Geoidal Separation can be set to ...
2
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1answer
128 views

Relation between Geoidal separation and antenna altitude in GGA sentence?

I have searched about definitions and relations about geoidal separation and antenna altitude reported in GGA sentence. The more I read the more I am confused.So in a simple manner can anyone explain ...
3
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0answers
50 views

Do locations “move” when shifting datum?

I hope that this is the right Stack Exchange for this question. I may be oversimplifying this, but I'm looking for verification in my understanding of the following: If I have a spatial dataset in 2 ...
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0answers
60 views

Strategies and methods that Datums and Coordinate Systems use to account for movement of the earth's surface

Are there datums and coordinate systems that address the issue of shifting coordinates through time? If so, what are some of the strategies and methods that the datums and coordinate systems use to ...
4
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2answers
117 views

Are Australian Height Datum and GDA94 applicable to Christmas, Lord Howe, and Norfolk islands?

I've been asked to recommend a mapping coordinate reference frame for use for Australian mapping, which I've said AHD for the vertical component and GDA94 for the the horizontal component. However, ...
3
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1answer
48 views

What does it mean for two datums to be navigationally equivalent?

I read from NOAA that NAD83 and WGS84 are "navigationally equivalent" NOAA uses the North American Datum of 1983 (NAD 83) for all of its charts. This datum is navigationally equivalent to the ...
0
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1answer
33 views

How to set datum in GPS connection setup window in ArcFM Viewer for ArcGIS Engine Application

I have a custom application based on ArcFM Viewer for ArcGIS Engine. I want to use an external GPS receiver with that application and the setup window does not let me choose a different geographic ...
10
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3answers
815 views

What is the meaning of “Elevation above the surface of the ellipsoid”?

I'm using implementation of Vincenty's algorithms, and I have their class called "position" that requires lat, lon, and elevation defined by: "Elevation above the surface of the ellipsoid". What is ...
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1answer
636 views

What is/are the coordinate systems used in South Africa?

What are the principal datums and projections used in South Africa including the names of geodetic datums and their projections?
0
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1answer
171 views

Difference between WGS_1984_UTM_33N and GCS_WGS_84

What is the difference between: a map that has a projected coordinate system of WGS_1984_UTM_33N, a geographic coordinate system of GCS_WGS_1984, and a datum of D_WGS_1984 a map that has no ...
1
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1answer
77 views

Geosoft Oasis Montaj Local Datum Transform - What is the purpose of this parameter?

When defining a coordinate system in Oasis Montaj one of the parameters is "Local Datum Transform". Is this the coordinate transformation definition to convert the defined coordinate system of a data ...
1
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0answers
39 views

Geographic coordinate system and datum [duplicate]

I am bit confused about datums used to define a localised coordinate system for a specific area. Definitions say that, datum defines how a certain well-established point (i.e., reference point) on ...
0
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1answer
82 views

ArcGIS 10.2.2 Does “Batch Project” work for different input datum?

I have two vector data sets - one is in NAD27 and the other is in WGS84. Normally I reproject one at a time. But can I just use 'batch project' to reproject both of them to NAD83 at once? I was not ...
4
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1answer
495 views

Canadian Geodetic Vertical Datum of 2013 (CGVD2013)

"Natural Resources Canada (NRCan) has released the Canadian Geodetic Vertical Datum of 2013 (CGVD2013), which is now the new reference standard for heights across Canada. This new height reference ...
3
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2answers
265 views

methods for converting coordinate datum and format in python?

Related to an earlier Q&A of Missing grid shift files for cs2cs.exe? ... what are the various methods to convert coordinate datum and format in python? (Windows Vista, python 3.4) For example, ...
1
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1answer
270 views

Transform coordinates in MapInfo with GSB data

Does anybody know if MapInfo (or MapBasic) is capable to do coordinate transformation using the NTv2 (National Transformation version 2) method? Currently Switzerland changes their national ...
3
votes
1answer
203 views

Reprojecting between NAD27 and WGS 84 part III

I am trying to perform a reprojection for data with datum Nad27 to WGS84 datum. According to AndreJ in some previous questions in Stackexchange (CRS reprojection for instance) QGIS uses internally by ...
1
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1answer
307 views

Project from Datum Nad27 to WGS84

This should be simple: have a shapefile in UTM z16 DatumNad27 and want to transform it to Datum WGS84 latlon I am using Qgis 2.6 Sorry I am going to clarify, with the steps taken: 1- XY data of a ...
2
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2answers
1k views

ArcGIS Desktop:Transformations: Geographic vs Projected?

Arc10. I have two data sets (both CSV files w/ lat and long columns) and I am working on standardizing them to the same projection. File1: NAD27; File2: NAD27, WGS84, and NAD83. I would like all of ...
2
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1answer
169 views

Coordinate display in Terrasync

I'm using Terrasync on a Trimble GeoXH 6000 - set for WGS 84 and UTM. It acquires satellites fine, but instead of displaying my current location in UTMS, the skyplot screen shows "12RVU" and then a ...
2
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2answers
5k views

Transforming coordinates between wgs84 and UTM ED50 31N, what am I missing?

My problem is I must tranform a point cloud from wgs84 (geographic) to UTM (projected) ED50 for zone 31North. Easy, isn't it? Well, first surprise is I have several free webs who offer me this ...
0
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1answer
55 views

Converting datum?

I need to measure the distance (with the ruler) of points from two different layers. However, one layer is NAD83 and the other is NAD27. I also have a standard ESRI basemap downloaded. The issue I ...
2
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3answers
93 views

Change projection didn't change position in a vector shape in qgis

I got a shape of points and when i save it with another datum and open it again, it stays in the same position. I was hoping for a slight change in position when save from epsg:5361 to epsg:32719.
7
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2answers
319 views

Geo-referencing an old map

I'm trying to georeference this part of an old map of Indochina. . The full extent gives more information: . To do so, I used QGIS and tried to infere the datum, I tried "Unknown datum based on ...
2
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1answer
88 views

Figuring out what coordinates supposedly using 'NAD31 projection' refer to

I'm working with a GeoJSON file that contains sets of coordinates associated with street corners in the city of Montreal, Canada. The spec sheet of the API delivering those GeoJSON specifies that the ...
0
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1answer
585 views

ArcGIS Conversion Error While Converting ED50 Datum to WGS84 Datum

With ArcGIS for Desktop, I tried a datum conversion of Transverse Mercator ED50 Datum to Transverse Mercator WGS84 Datum. Normally, the difference between two projections is approximately 180 meters ...
1
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1answer
222 views

Find AB_CSRS.gsb for NAD_1983_TO_WGS_1984_8 Transformation

I am trying to change my WGS84 data to NAD83 for Alberta data. My research tells me that I need to use the NAD_1983_TO_WGS_1984_8 Datum Transformation which is in the AB_CSRS.gsb. I can not find this ...
0
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1answer
28 views

NAD conversion in Mexixo

I am looking for the file "Mexico.gsb" which used with ArcGIS when datum shifting from NAD27 to NAD83 in Mexico.
3
votes
1answer
243 views

Why not measure elevation from the center of the earth?

In trying to understand Geoid vs Ellipsoid height, I ran across this page. One of the claims is: Zero elevation as defined by Spain is not the same zero elevation defined by Canada ...
2
votes
1answer
221 views

Origin of the OSGB36 datum origin

Interpreting 'GIS' in the geographical information science sense, I have a historical question about the 1936 OSGB datum following the 1936-62 retriangulation of Great Britain - hopefully not too ...
1
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1answer
671 views

Persistent datum conflict error. Datums are the same

I'm clipping a number of features using other feature layers, and was careful to get everything into WGS84 beforehand, using what I thought were the proper datum transformations. Now I keep getting ...
1
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2answers
723 views

Myanmar Datum 2000 information

Does anybody know where I can find the technical details for Burma's latest datum? It's called Myanmar Datum 2000 and I can't find any details online. I need the details to create a custom datum on my ...
3
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2answers
68 views

What is the closest CRS to “Meridiano de Greenwich”

I have a 1906 scanned map that I am trying to georeference in QGIS for Mac. The map has French and English lat-long, indicating them as either "Meridiano de Greenwich" or "Meridiano de Paris." I would ...
4
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2answers
967 views

Geographic Transformations in Alaska Between NAD83 and WGS84

I have done a ton of research on the most accurate transformation to use in mainland Alaska to convert between the NAD83 and WGS84 datums, but I just can't seem to find a definitive answer. ArcMap ...
1
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1answer
108 views

OpenLayers Projection and Datum Question

I had a conversation with a co worker that was asking about an OL map I am developing. She asked me what the 'projection' was and I said EPSG:4326. She didn't know what that means, so I said it's ...
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0answers
44 views

Are ellipsoid and datum the same? [duplicate]

Are the datum and the ellipsoid the same? What is a Datum? The Earth is shaped like a flattened sphere. This shape is called an ellipsoid. A datum is a model of the earth that is used in ...