Linked Questions

16 votes
2 answers
67k views

Is WGS84 a Coordinate system or projection system? [duplicate]

WGS84 is often referred to as a "projection system" and sometimes it is confusing to me about what a "projection system" is and where WGS84 falls in one. Could someone please clear that up for me?
ImaneKtb's user avatar
  • 351
3 votes
2 answers
2k views

What is the difference between a datum and an ellipsoid? [duplicate]

For example I am converting from ECEF to lla using def ecef_to_lla(x, y, z): lla = pyproj.Proj(proj='latlong', ellps='WGS84', datum='WGS84') ecef = pyproj.Proj(proj='geocent', ellps='WGS84', ...
nickponline's user avatar
1 vote
0 answers
168 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 mapping. ...
THILINA's user avatar
  • 11
1 vote
0 answers
115 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 ...
Shrestha's user avatar
0 votes
0 answers
109 views

what is the difference between the Geographic coordinate, transformed coordinate and screen coordinate [duplicate]

What is the difference between the Geographic coordinate, transformed coordinate(projected) ,cartesian coordinate, and screen coordinate? Is there a live example? And what is the association between ...
giser's user avatar
  • 953
25 votes
7 answers
4k views

Spatial reference for dummies?

Can anyone recommend a good reference or tutorial that explains the principles of spatial references, projections, and coordinate systems? We are a small team of programmers working with GIS ...
21 votes
5 answers
25k views

What is projection of WGS84 in GIS software? [duplicate]

WGS84 is a reference ellipsoid that determines coordinates of every point on Earth using latitude, longitude and height about the its surface. This ellipsoid is often used as a base to make maps. ...
multigoodverse's user avatar
30 votes
2 answers
109k views

Understanding difference between Coordinate System and Projection?

Can somebody please explain what is the difference between the Coordinate system (WGS 84 for example) and a Projection (Universal Transverse Mercator for example)? What is the difference between a ...
marco's user avatar
  • 1,137
7 votes
1 answer
10k views

Latitude, longitude, projections, CRS [closed]

I'm confused about the following basic points: Do lat/long points have a projection or are they projection agnostic? Do these points live in a sphere or a plane? I understand that projections are ...
xv70's user avatar
  • 231
0 votes
2 answers
4k views

How would I convert this point to WKID 4326?

This is a point in Brewster, MA, USA. How would it be converted to WKID 4326? 324299.3348436486, 832511.5939650714
Seibar's user avatar
  • 103
4 votes
2 answers
7k views

Converting NAD83 (epsg:4269) to WGS84 (epsg:4326) using pyproj

I'm trying to convert US census data (NAD83) to WGS84. I know the difference between the two is quite minor, but trying to apply the transformation using pyproj does not do anything. e.g.: from ...
Zohar Bar-Yehuda's user avatar
7 votes
1 answer
2k views

Vertical Datum and Projection

Does vertical datum get projected? I feel a bit confused with the concept of the vertical datum and doing a projection.
Carrie's user avatar
  • 71
4 votes
3 answers
4k views

Advanced Digitizing Panel Not Enabled When Map View is in Geographic Coordinates

I am trying to use the advanced digitizing panel with a new line geometry layer. I am using QGIS 3.0.3 The QGIS documentation states: "The tools are not enabled if the map view is in geographic ...
That60sKid's user avatar
2 votes
1 answer
4k 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 projected ...
Geoniette's user avatar
2 votes
3 answers
1k views

Understanding map projection coordinate systems

I have been playing around with a variety of map projections for the purposes of transforming between various representations. The thing that I still don't quite understand is how to interpret the (x,...
marcman's user avatar
  • 121
4 votes
3 answers
367 views

Determining if file in projected or geographic coordinates using ArcGIS Desktop?

I have download the European grid DEM raster data from Copernicus website, which I would like to use to calculate solar radiation for smaller study site. The ArcGIS:Area solar radiation tool requires ...
maycca's user avatar
  • 3,376
3 votes
1 answer
2k views

Which BC Albers should I use and is there any difference?

I was about to calculate the area of some polygons and before I did I did some research. I found that the area of the polygon will be represented in the units of the projection used. So I did some ...
Chewy's user avatar
  • 583
1 vote
2 answers
3k views

Difference between EPSG:4326 and EPSG:32637?

I'm exporting data from a program into a .csv for RStudio, which will then go into ArcMap. I haven't done this before and I've been given two projection options which are: WGS 84 [EPSG:4326] WGS 84 / ...
Eal20's user avatar
  • 11
-2 votes
1 answer
908 views

QGIS exporting shapefile with proper projection

Can someone walk through the proper way to set a projection and export the shapefile so it will properly open up in another GIS program? I'm having trouble.
Mike Guillen's user avatar
3 votes
1 answer
664 views

What are the highest and lowest precision Coordinate Reference Systems for US East Coast?

And does it matter what system your data layer begins with if you choose the right system for your project? Do some applications use more precise projection systems than others?
Fred's user avatar
  • 239
4 votes
1 answer
616 views

No difference between distances measured in projected and non-projected data

I'm performing measurements of distances in Km between a lot of localities by using the "Point Distance" in ArcGis 9.3. I realized that the results obtained after using projected coordinate system are ...
user avatar
3 votes
2 answers
1k views

Projecting vs. export using data frame projection?

I have two shapefiles with different projections. When I load both into ArcMap I get the 'Geographic Coordinate Systems Warning' when the second is loaded into table of contents but they both align ...
Ian Schelly's user avatar
1 vote
4 answers
597 views

Effect on using different spheroids system

Recently I am investigating case of grounding vessels, one of the findings is the paper chart used for passage planning was using Bessel 1841 spheroids, whilst the GPS system was using WGS 1984 ...
aleik nurwahyudy's user avatar
1 vote
1 answer
935 views

Choosing best projection/SRID

I created a shape in OpenJump and exported it to shape(ESRI) file and then imported it to SQL2008 via shape2sql , the problem is that it shows bigger than what I want, In OpenJump it shows 1meter ...
AliRezza's user avatar
  • 339
0 votes
1 answer
862 views

SRID, Shape2SQL and SQL Server 2008r2 query

I'm using Shape2SQL to load the Ordinance Survey's Meridian 2 map into SQL Server 2008r2 (which is working very smoothly and painlessly). According to this page (https://alastaira.wordpress.com/2011/...
Matthew's user avatar
1 vote
2 answers
484 views

How can I make the UTMs of different datasets uniform?

I have wind datasets for every U.S. state and want to merge them. I found out that these datasets use different UTMs. So I want to make the UTMs uniform. How can I do that? This can not simply be done ...
Stefanie's user avatar
3 votes
0 answers
446 views

Why do each of my buffer-polygons have different areas

I`m using Qgis 2.2 and 2.4 and loaded a wms-map using the coordinate system ERTS89 UTM 32N. I set 8 points (all in on shp-fileand in UTM 32N) on various locations on the map. After that i created a ...
Chris's user avatar
  • 31
6 votes
1 answer
256 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 ...
Keegan Smith's user avatar
2 votes
0 answers
402 views

Reprojecting raster file with unknown datum using ArcGIS Desktop?

I am new to GIS. I had a grib format data file and it's coordinate system shown below. I want to project it to WGS84, however, the datum of original file is unknown. I know I need to provide the datum ...
Krystal's user avatar
  • 29
-1 votes
1 answer
214 views

What is a coordinate system?

Please help me understand a coordinate system and how a coordinate system is relevant to a region of interest such as South Africa. I came across this term a couple of times and overlooked it because ...
eldix_'s user avatar
  • 111

15 30 50 per page