6

I haven't received a reply posting this same question on the Natural Earth forums, so I figured I'd give it a try here.

I’m trying to reproject the 1:10m "Admin 0 – Countries" shapefile into a Web Mercator projection (EPSG:3857) using QGIS. However, the reprojection fails with the following message:

Export to vector file failed. Error: Failed to transform a point while
drawing a feature of type ‘ne_10m_admin_0_countries’. Writing stopped.
(Exception: forward transform of (3.141593, -1.570796) PROJ.4:
+proj=longlat +datum=WGS84 +no_defs +to +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs 
Error: tolerance condition error)

I receive this error for both "ne_10m_admin_0_countries" and "ne_10m_admin_0_countries_lakes".

A post here on gis.stackexchange.com indicates that it might be a problem with points in Antarctica going to infinity during reprojection, but I’m not sure how to fix it if that is indeed the problem.

The 1:50m "Admin 0 – Countries" shapefiles are able to be reprojected successfully using QGIS, which leads me to believe that the root of the problem may lie in the 1:10m shapefiles.

I'm hoping that someone can expand on the answer offered in the linked post and provide answers for the following questions:

  • Is there an error in the 1:10m shapefile? (Since the 1:50m shapefile reprojects without issue) Or is this sort of reprojection error just to be expected under certain circumstances?
  • Exactly what steps may I take to fix the shapefile so that it can be successfully reprojected? The linked post says to "delete the objects around the south pole" but I'd prefer not to delete Antarctica. I tried editing the Antarctica feature to chop off the southernmost portion, but it didn't seem resolve the reprojection error.

Please assume I'm a GIS newbie.

Thanks!


RESOLUTION & NEW SHAPEFILES

Second try was the charm for me, and I was able to trim off the bottom of Antarctica using the "Reshape Feature" tool in QGIS. There's a decent description of how to use it here: https://gis.stackexchange.com/a/21651/1770. After removing the southernmost portion of Antarctica, I was able to successfully reproject the map.

To save everyone some time, I've posted the files. These are the "_lakes" files that do NOT include boundary lakes:

Improve this question
6
  • the post you link to contains a clear answer to your problem
    – Ian Turton ♦
    Jun 14, 2013 at 7:25
  • The post I link to does not answer the following questions: Is there an error in the 1:10m shapefile (since the 1:50m shapefile reprojects just fine)? How may I go about fixing the shapefile so that it can be reprojected? All the post says is "delete the objects around the south pole", and I'd prefer not to delete Antarctica.
    – David Mills
    Jun 14, 2013 at 13:45
  • 1
    Don't try to project files that contain data north or south of 85 degrees in to Google Mercator.
    – Ian Turton ♦
    Jun 14, 2013 at 15:26
  • The 1:50m shapefile contains data south of 85 degrees and reprojects without issue. Also, I'm still interested in an answer to both of my questions. Exactly what steps may I take to fix the 1:10m shapefile so that it can be successfully reprojected?
    – David Mills
    Jun 14, 2013 at 15:33
  • I re-opened the Q since David revised it sufficiently to show what makes this different from the linked duplicate. However since it is a specialized problem relating to a single dataset there is potential for it to be closed again as 'too localized'. We'll see what kind of answers are turned up.
    – matt wilkie
    Jun 14, 2013 at 16:09

1 Answer 1

Reset to default
3

The error message is reasonably clear--there's a problem at longitude = 180, latitude = -90 (given values are in radians). I downloaded both datasets and displayed them together in ArcMap. When I checked Antarctica, the 1:50 million data has its southernmost line at approximately -89.9989, while the 1:10 million is -90.0. Clip off the bottom of Antarctica slightly and you should be good to go.

Improve this answer
1
  • Ok, second time was the charm for me. I'm not sure what I did wrong the first time when attempting to chop off the bottom of Antarctica, but the key tool to use in QGIS is called "Reshape Feature". There a decent description of how to use it here: gis.stackexchange.com/a/21651/1770. After removing the southernmost portion of Antarctica, I was able to successfully reproject the map.
    – David Mills
    Jun 18, 2013 at 15:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.