Linked Questions
32 questions linked to/from Difference between projection and datum
18
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2
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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?
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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', ...
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1
vote
0
answers
170
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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.
...
- 11
1
vote
0
answers
119
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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 ...
- 51
0
votes
0
answers
110
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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 ...
- 803
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. ...
- 1,545
31
votes
2
answers
115k
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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 ...
- 1,147
7
votes
1
answer
11k
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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 ...
- 231
0
votes
2
answers
4k
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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
- 103
4
votes
2
answers
8k
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 ...
- 141
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.
- 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 ...
- 187
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 ...
- 31
2
votes
3
answers
2k
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,...
- 121
4
votes
3
answers
409
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 ...
- 3,386
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 / ...
- 11
4
votes
1
answer
3k
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 ...
- 593
-2
votes
1
answer
1k
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.
- 281
3
votes
1
answer
793
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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?
- 239
4
votes
1
answer
620
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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 ...
e-falcon
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 ...
- 63
1
vote
4
answers
624
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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 ...
1
vote
1
answer
963
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 ...
- 339
0
votes
1
answer
871
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/...
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1
vote
2
answers
539
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 ...
- 79
3
votes
0
answers
465
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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 ...
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6
votes
1
answer
293
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 ...
- 141
2
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0
answers
410
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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 ...
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-1
votes
1
answer
219
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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 ...
- 111
0
votes
1
answer
64
views
Measuring distance from points to polygon: won't measure in metres!
I'm using ArcGIS 10.2. I have some point data (sampling points) and I want to know how far each of these is from the nearest protected area (polygon data). I have tried doing this with both the Join ...
1
vote
0
answers
33
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Do i need to list projection on map when using wgs84
I have been creating maps using project CRS:WGS84 or ESPG:4326 when I export these maps (with grids listing the coordinates and suffix) I have just been writing on the map CRS:WGS84. Should I be ...
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