QGIS 2.4 - shape files do not overlap

1
votes

I am new to QGIS and currently using QGIS 2.4. I need a help plotting these 2 files.

http://www.eia.gov/maps/map_data/EIA_States_MapLayer_CoalMines.zip (EPSG:2163 - US National Atlas Equal Area)

http://dds.cr.usgs.gov/pub/data/nationalatlas/railrdl010g.shp_nt00917.tar.gz (EPSG:4269 - NAD83)

Somehow, the 2 files do not overlap correctly in QGIS when I load the vector layer. I tried changing the CRS to EPSG:2163 - US National Atlas Equal Area for both the layers but they still do not overlap.

I have tried changing the CRS to other combinations but unable to fix the problem.

Appreciate if someone can point me in the right direction.

Regards

3
vectoroverlapqgis
Hard to be sure if this is the problem, but changing the CRS for an individual layer doesn't re-project it, it just tells QGIS what coordinate system the underlying data are in. Try to make sure each layer is set to its actual CRS and make sure you've enabled "on-the-fly" re-projection in the project properties. You could also try re-projecting one of the files into the others CRS using OGR or something. – kueda
This maybe a silly question, how do i find out what is the actual CRS for a layer? I tried looking at the websites but was unable to find any information there. – GunMetal
Not silly! Look in the .prj file if one is there. It should specify how/if the data are projected, and what the coordinate system might be. If that's not there, look through any metadata you can find (e.g. xml files that came with the data) for hints. If you know who made the data, you could also ask them. If you're comfy on the command line, ogrinfo will also tell you things, e.g. ogrinfo -al CoalMines.shp |less – kueda

3 Answers

0
votes

This is how I was able to solve the problem with some help.

The coal mines data is in a Web Mercator: http://spatialreference.org/ref/sr-org/wgs_1984_web_mercator_auxiliary_sphere/

This is not included in Spatialite, PostGIS or QGIS which all use Proj4.

Fix: The data itself has lat/lon coordinates, so export as txt/csv file (rightclick - save as) Read it back in using the "Add Delimited Text Layer" tool. X will be 'long' field, y will be 'lat' field. Set the project to be WGS 84 just to be safe and it came in on the railroad layer.

0
votes

For anyone else dealing with this problem:

  • Right-click Layer > "Set Layer CRS" > "EPSG:3857"
  • Project > Project Properties > Enable 'on the fly' CRS transformation
0
votes

In case anyone else is trying to use the EIA's shapefile data:

In Settings -> Options -> CRS tab, you can select to Prompt for CRS for new layers.

Then, specify a projection similar to 'WGS_1984_Web_Mercator_Auxiliary_Sphere'. At first glance, Google Mercator appears to work.