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Questions tagged [datum]

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

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Turkish National Geodetic Network parameters, Turkish National Vertical Control Network (TUDKA-99) & Turkish Fundamental GPS Network 1999A (TUTGA-99A)

I have a shapefile with the GCS_TUREF coordinate system. The client's requirement is to align the GIS files with the parameters of the Turkish National Geodetic Network, specifically the Turkish ...
Sunanda Mukherjee's user avatar
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36 views

Converting vertical datum of Lowest Astronomical Tide (LAT) to EGM96

I want to model the impact of sea level rise (SLR) on the coast zone of an Asian country using a modified bathtub model. The SLR projections include AR6 results and extreme sea level (ESL) by high ...
Yuxuan Ye's user avatar
1 vote
0 answers
55 views

Rasterio convert vertical datum of NAVD88 to WSG84

I've been asked to provide an elevation data for projected to GPS. To achieve that i've tried to convert the NAD83 geotiff with NAVD88 vertical datum (downloaded from USGS) into WSG84. To do the ...
Szymson's user avatar
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71 views

Identifying the coordinate system in a set of Australian data

I have the following set of data. Name Easting Northing Point 1 7675 0576 Point 2 7758 0330 Point 3 7568 0864 I would like to know what coordinate system this data uses, to convert it to latitude ...
TigerTen's user avatar
1 vote
1 answer
130 views

autonavi / amap xyz tile layer appears shifted in OpenLayers (Chinese Web Mercator with GCJ-02 datum)

I am trying to add an xyz source tile layer to OpenLayers v8.1. The source URI for the tiles is the Chinese autonavi / amap provider. http://webrd0{1-4}.is.autonavi.com/appmaptile?lang=zh_cn&size=...
Dennis Bauszus's user avatar
1 vote
0 answers
453 views

Converting geodetic coordinates to ENU coordinates

I am trying to understand conversion from geodetic coordinates to ENU coordinates. As per this wikipedia page, its two step process: geodetic to ECEF coordinates and then ECEF coordinates to ENU ...
RajS's user avatar
  • 111
2 votes
0 answers
48 views

Location from which QGIS reads datum transforms

I am trying to transform coordinates from the Adindan datum (EPSG:4201) to the WGS-1984 datum (EPSG:4326) using the transform Adindan to WGS 84 (6) (EPSG:1105). But when I try to select it, QGIS only ...
Luigi's user avatar
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138 views

Vertical transformation of DEM from NAVD88 to CGVD2013 datums

I am attempting to recalculate a DEM raster from the vertical datum of NAVD88 to the 'new' Canadian vertical datum, which is CGVD2013. I've looked at a few similar questions but they only are geoidal ...
Matt Canada's user avatar
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96 views

More information on transformation warning

Software: ArcGIS Pro 2.9.5 Issue: datum transformation error Want: some details on where the error can be found Detail: like most folks at some point, I am getting a "transformation warning" ...
somegismurph's user avatar
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1 answer
212 views

Convert XYZ file with WGS84 Ellipsoid elevations to EGM96 Geoid elevations

I have multiple files in XYZ format in UTM horizontal + WGS84 ellipsoid vertical that I need to convert to UTM horizontal EGM96 geoid elevations. There are about 250'000 points in a an area that is ...
tukanium's user avatar
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Are datum and geodetic datum the same?

Although I really read many post and text book, I really don't know 'datum' and 'geodetic datum'. If they are different, could you tell me how?
Jiyeon Kim's user avatar
1 vote
0 answers
79 views

Convert GPS heights to AHD

My workplace is looking to replace our Geo 7X and TerraSync. We are looking to replace the Geo 7X with the Trimble DA2 and replace TerraSync with QField. I'm currently trying to test QField and see if ...
Mow's user avatar
  • 175
1 vote
1 answer
687 views

NAD83 / NAD83 HARN datum transformation

I have data in two projected coordinate systems (PCS), 1) NAD 1983 HARN StatePlane California III FIPS 0403 (US Feet), and 2) NAD 1983 StatePlane California III FIPS 0403 (US Feet). Using HARN, ...
somegismurph's user avatar
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1 answer
189 views

Mobile phone GPS altitude decreases when measured from high rise buildings

I am using my mobile phone (Motorola G30) in which I had installed GPS Test app, to measure altitude. I am coming across something really weird. Attached is the screengrab comparing the altitude ...
karthikeyan's user avatar
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1 answer
1k views

Difference between WGS84 datum and WGS84 UTM 15N [closed]

I have two digital elevation models. One’s datum is in WGS84, and the other datum is WGS84 UTM 15N. I am using both for geologic mapping. What’s the difference between the two datum? Is it okay for ...
Programmer888's user avatar
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86 views

Using Project tool in ArcMap

I am trying to get my shapefiles to line up using the project tool. This is the information of the "Input Dataset or Feature Class" Data Type: Shapefile Feature Class Shapefile: C:...
Yoshihiro G Yagi's user avatar
5 votes
1 answer
151 views

How is datum used in assigning lat and long to point on Earth's surface?

It's accepted wisdom that geographic coordinate systems require a datum in order to assign lat/long to a point on Earth's surface. However, every point in 3d space already has 3d polar coordinates ...
Sideshow Bob's user avatar
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533 views

Vertical Datum transformation for raster using ArcGIS Pro

I have a DEM raster file on WGS84 CRS and height referenced to ellipsoid on same datum. I want to convert that DEM to local CRS (horizontal & vertical) including the vertical datum transformation. ...
user4906240's user avatar
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209 views

Gridshift in QGIS 3

I try to access to a specific gridshift for a projection but It doesn’t appear in the datum transformation window. I’m working on QGIS 3.16.16. I want to use the NAD8398.gsb (from NTv2) in a ...
Jonathan's user avatar
1 vote
1 answer
841 views

If NAD83 is a datum and not a projection, what is happening when set CRS = EPSG:4269 (NAD83)

My understanding is that different projections can use the NAD83 Datum i.e. UTM, Lambert Conformal Conic. But what happens when I'm working in R and I set the CRS of a shapefile to EPSG:4269 (https://...
canderson156's user avatar
2 votes
1 answer
301 views

Lowering GeoTIFF raster by fixed value using QGIS

I'm trying to find a way to lower a GeoTIFF raster file by a fixed value. I will try to describe my process so far. I start by downloading a GeoTIFF from the usgs webviewer, these are in CRS "...
Jesse G's user avatar
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1 answer
322 views

Defining Geographic Transformation in Project Raster using ArcGIS Pro

I am using ArcGIS Pro 2.9. I have a raster in D_NAD_1983_2011_Transverse_Mercator and wish to project it to WGS_1984_UTM_Zone_12N so I may export this projected raster as a .tif file. I have tried ...
geotocho's user avatar
5 votes
2 answers
1k views

Convert Vertical Datum of GDAL file

I have 2 DTM datasets, the first has a vertical datum of WGS84, while the second has an orthometric vertical datum (maybe EGM96). gdalinfo seems to only provide the horizontal datum info: Size is ...
Daniel C Jacobs's user avatar
2 votes
1 answer
889 views

Identifying vertical datum of raster

I have a DEM that purports to use the Canadian Geodetic Vertical Datumn 1928 (CGVD28) where heights are normal-orthometric. However, when I run gdalinfo dem.tif from the command line the output for ...
standbybee's user avatar
2 votes
0 answers
234 views

How is Trimble Pathfinder Office transforming positions?

I am struggling to understand how Trimble’s Pathfinder Office transforms and exports GNSS data and I’m hoping someone here can explain. I've seen posts like this and this, and documents like this, but ...
c_herrick's user avatar
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1 answer
359 views

Raster does not match the target extent and shape of another raster ArcGIS

I have future climate data in .nc format. I transferred them into multiband rasters so I can separate them using another tool and make some calculations. I faced one issue in one variable where it had ...
Areej's user avatar
  • 27
2 votes
1 answer
280 views

Finding the correct aspect ratio from image

I'm trying to put an image over my map. I know the correct bounding box of it, but when I load it, I see it doesn't fit correctly in the map. Just for curiosity, I cut a piece of map of same region ...
Magno C's user avatar
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1 vote
1 answer
250 views

Custom datum transformation in Python

I need to transform a shapefile from Deir ez Zor / Levant Stereographic (EPSG:22780) to UTM 36N using 7-parameters Helmet transformation on Python script. In ArcGIS, I can achieve the following using ...
Ali J. Ghandour's user avatar
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1 answer
100 views

vDatum returns error at Linux command line - fails to accept parameters with GUI

I am trying convert a GeoTiff using VDatum at the Linux command line. My data reference the Washington State Plane South CRS with z values referencing EGM96. I would like to convert these z values to ...
GBG's user avatar
  • 9,940
0 votes
0 answers
141 views

Identifying undefined vertical datum

I was given two DEM files covering the same area of Northern California (lets call them File_A and File_B). They're derived from LiDAR that was flown separately in the last 10 years. My goal ...
Adam C's user avatar
  • 217
1 vote
1 answer
431 views

PostGIS ST_Transform seems to treat the vertical datum but not the equivalent pyproj Transformer, even so they both rely on Proj

I've narrowed down a problem I met when processing some points having altitude values to the following: It seems that PostGIS and pyproj do not treat the vertical datum in the same way but both are ...
swiss_knight's user avatar
  • 10.4k
1 vote
0 answers
129 views

Datum transformation with velocity corrections

I have a coordinates with velocity values of some points in ITRF2014 at 2010.0 epoch and I want to convert these coordinates to ITRF96 1998.0 epoch. I apply the velocity corrections to my coordinates ...
Sun's user avatar
  • 113
1 vote
0 answers
330 views

Special relationship between EPSG:4326 and EPSG:4369

This is a follow-up question to a previous one (Projection between EPSG:4326 and EPSG:4269 using pyproj does nothing). When using pyproj (python 3.8.8 and pyproj 3.0.1 on windows) to project a point ...
Anon_Chem's user avatar
1 vote
0 answers
277 views

Projection between EPSG:4326 and EPSG:4269 using pyproj does nothing [duplicate]

According to this quite thorough answer : Is re-projection needed from SRID 4326 (WGS 84) to SRID 4269 (NAD 83)? the crs EPSG:4326 and EPSG:4269 are slightly different, due to a difference in one of ...
Anon_Chem's user avatar
1 vote
0 answers
106 views

Datum transformation not working properly [closed]

I want to create a map with 20 coordinates (UTM), that I have loaded as a CSV-file into QGIS 3.12. The area is located in UTM zone 32 U (northwest of Munich). As a background I want to use an 80 cm ...
Victor's user avatar
  • 19
0 votes
2 answers
2k views

Transformation datum from WGS84 to BTM (Bangladesh Transverse Mercator)

I'm changing raster layers in ArcMap from WGS84 to BTM (Bangladesh Transverse Mercator). I first set my data frame to be in BTM [BTM Projection: Transverse_Mercator False_Easting: 500000.0 ...
Areej's user avatar
  • 27
2 votes
0 answers
60 views

Visualizing resource dependencies and relationships underlying EPSG CRS

I'll go straight to the point; I remember long ago that I was quite shocked the first time I discovered that EPSG:4326 was kind of an "umbrella" definition on top of many others, which often ...
swiss_knight's user avatar
  • 10.4k
0 votes
1 answer
153 views

NAD27 data distributed in NAD83 by Canadian government

Natural Resources Canada (NRCAN) produced 1:50000 topo maps for all of Canada according to the Natural Topographic System grid configuration. The maps are now considered a legacy product, but GeoTIFFs ...
tomfumb's user avatar
  • 3,678
2 votes
1 answer
268 views

EPSG for TanDEM-X Ellipsoid

I have TanDEM-x data and according to the documentation: "The elevation values represent the ellipsoidal heights relative to the WGS84 ellipsoid in the WGS84-G1150 datum." I would like to ...
GeoMonkey's user avatar
  • 1,357
8 votes
1 answer
2k views

Understanding EPSG in WKT

I notice several EPSG codes in one WKT. At the first glance it almost is non-intuitive to see so many EPSG codes linked to a single EPSG. Can someone explain each line of the following WKTs for EPSG:...
GISEnthu's user avatar
  • 101
0 votes
2 answers
111 views

Drawing two points in two datums with same coordinate value

Today I was trying to use ArcMap to find out what is the distance between two locations with same coordinate values in NAD27 and NAD83, but the points I drew appeared to be at the exact same location. ...
LamberWBY's user avatar
1 vote
2 answers
115 views

Failure to project shapefile to Mass State Plane NAD83 (meters) SRS with ArcMap

I am working with a shapefile that I have not been able to project to the Mass State Plane NAD83 meters (i.e., EPSG:26986) SRS using ArcMap's "Project" tool. The "Project" tool ...
Ben Krepp's user avatar
0 votes
0 answers
221 views

Why do I continue to get a datum conflict message even though layers match?

I have a document with multiple raster layers and a set of buffer zones for which I am trying to use the zonal statistics tool to summarize some of the raster information within the buffers. Most of ...
fin's user avatar
  • 35
0 votes
0 answers
178 views

Using NTV2 transformations in MapInfo

I am investigating the use of MapInfo to apply transformations between GDA94 and GDA2020. I am using MapInfo Pro 2019.1 so the NTv2.xml file has 10 entries relevant to Australia. They come in pair ...
TazAstroSpacial's user avatar
0 votes
1 answer
265 views

Setting a custom projection in ArcGIS, from data provided by the Government of Mauritius?

I am trying to save a custom projection in ArcGIS. It is a local projection used by the Land Unit from the Government of Mauritius. Below are the information provided by the government: My question ...
StainlessSteal's user avatar
1 vote
1 answer
1k 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 ...
Brannon's user avatar
  • 165
1 vote
0 answers
446 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? ...
PPR's user avatar
  • 511
5 votes
0 answers
142 views

Datum transformation in QGIS Server 3.10 [closed]

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 ...
andrew's user avatar
  • 51
7 votes
1 answer
594 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 ...
Jeff's user avatar
  • 79
1 vote
0 answers
644 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 ...
Jeff's user avatar
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