I want to create points from lat/long data. I used "File" -> "Add Data" -> "Add XY Data..." to create the points. I am 100 % positive that a I used the right columns for X and Y and I selected the correct CRS. I checked multiple times.
However, when creating the points they are just centimeters apart from each other, using the Measure tool to measure distance. That cannot be correct.
I also used "Add Layer" -> "Add Delimited Text Layer" in QGIS and got the correct locations of the points. It would be better for me to do the action in ArcMap though, since I need to load over 300 of the files and want to build a model later on to do that.

The coordinates are:

enter image description here

The CRS is ETRS_1989_UTM_ZONE_33N
I use ArcGIS 10.3 on Windows 7

What am I doing wrong/what could be the reason for the misplacement of the points in ArcMap?

I know that the points should be around 570 m apart from each other.

  • No, nothings changed. Thanks for the suggestion though. – blabbath May 29 at 9:26
up vote 4 down vote accepted

ETRS_1989_UTM_ZONE_33N is a projected coordinate system, with units in metres. If you have lat-long coordinates in decimal degrees, they can't be in that CRS.

Tell ArcGIS that the coordinates are EPSG:4326 and you'll likely as not get them in the right place. This is the default for QGIS which might explain why it gets them in the right place. What have you done to tell ArcGIS about the UTM Zone coordinate system?

Internally, the GIS (ArcGIS or QGIS) is storing the lat-long numbers. It uses its knowledge of the projection to figure out where on the earth they are. The EPSG:4326 code is a shorthand for the lat-long coordinates that the GPS system uses, and has become a default for most mapping. So it goes "okay, 21.3N 38.6E is.... here on the screen" and draws a dot.

But if you want to do things with coordinates in a small area, i.e. not global, you might want to use a planar coordinate system that works like a grid on a piece of graph paper. You can then compute distances using Pythagoras' theorem, for example, rather than working out the more complex geometry for distances on an ellipsoid.

For this you need a coordinate system like the UTM Zone system. You need to tell your GIS that you want to convert the layer from EPSG:4326 to EPSG:25833 (which I think is the right one for that). Then internally your GIS will change its stored numbers from 21.3N 38.6E (or whatever) to 626300, 147363, these being metres N and E of the origin of the coordinate system.

Note that two things are happening here - the GIS is changing the internally stored coordinates of your data from one system to another, and it is changing the metadata of the data to indicate which coordinate system the numbers are. You have to keep both in sync or you end up with a mismatch.

A GIS might let you set just one of these, for example assigning a new coordinate system to an existing data set without transforming the coordinates. Now you have 21.5, 38.6 stored as coordinates and the metadata as UTM Zone 33, and now the GIS will plot it 2.15 metres north and 38.6 metres east of the origin, which isn't where it should be.

  • Could you give some further information on the last sentence of your answer? – blabbath May 29 at 9:45

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