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I'm trying to make a hex map of a country (Russia, in this case). To do this, I've opened a map of Russia in QGIS (from Natural Earth), set up my projection, and created a hex grid with MMQGIS. So far, so good.

Now I want to crop the hexes with the shape of Russia. I've tried using the intersect option, but I get this error:

"Input CRS error: One or more input layers missing coordinate
 reference information, results may not be as expected."

and an empty shapefile for my troubles. What am I doing wrong?

UPDATE: Ok, so now I have them both in the same coordinate system (based on an Albers projection using meters), but I'm still not able to get an intersection to work:

Warnings: Input CRS error: One or more input layers missing coordinate reference information, results may not be as expected. GEOS geoprocessing error: One or more input features have invalid geometry. Some output geometries may be missing or invalid.

The output shapefile is empty.

I was able to generate a version that almost works using WGS84 coordinates, but that had some problems with the 180° meridian...

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    I think you need to set coordinate systems of your data and for the project. I suppose you are using default WGS84 , but the units of your data are in some metric system, therefore there is no intersection. – Zbynek Feb 6 '14 at 13:23
  • Ah, this does sound right—I'm using an Albers projection, and I can't convince QGIS to not do it in meters. That's a separate question, though... thanks! – futuraprime Feb 6 '14 at 13:49
  • It would be better for you just to edit this question rather than asking a separate one--otherwise our site would get littered with orphan, disconnected unanswered questions. (Editing is fine up to the point somebody offers an answer. After that you need to be more careful with edits.) – whuber Feb 6 '14 at 14:07
  • Since the world isn't flat and doesn't end at 180E but your data thinks it is, you will be hitting issues with this. You could switch to using a system that fully understands that the world is an ellipsoid, but the simplest fix is probably just to offset Russia a bit to the west, merge the polygons that was clipped by the anti-meridian, perform the clip and then move them back east and redo-the clip at the anti-meridian. – dotMorten Feb 7 '14 at 0:40

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