The world countries showing problem about vega

[wrobstory]

It's some sort of error in the mercator projection- try using something like equirectangular or winkel3, and the map looks a little more normal.

[tony612]

@wrobstory thx.
I tried, it's better than mercator, but it seems there is still something wrong:
When I don't hover over on the map it is:

Then when I hover over:

The opacity of the countries should become 0.5 but not. and there is the blue background and opacity of it turns 0.5. (PS: I think the background of it should be transparent)
And the winkel3 project has the same problem.

[RutgerK]

I had the same problem with Mercator.

@tony612, there is probably some error in the geojson geometries. I can replicate it if i use yours. When i made my own geojson by exporting the "Natural Earth 110n countries" shapefile with ogr2ogr it works as expected. In the picture i'm hovering China, all geometries seem to work fine.

[tony612]

I used this data, global_world to show the map, it shows normally. I think there is something wrong with my data. :)

But the mercator has not been fixed.

Has someone tried to fix it?

[mbostock]

The first error is because Vega presumably inherits D3’s default projection, d3.geo.albersUsa which as you might guess is U.S.-specific. (It’s a composite projection for the 48 contiguous United States, Alaska, Hawaii and Puerto Rico.) You’ll need to specify a different projection for a world map; choose one of the many other available projections.

The other error looks like a problem with winding order in your GeoJSON file, where the polygons are not in clockwise order. I’m not sure if Vega supports TopoJSON yet, but I highly recommend it as you can get much smaller data files (as well as the useful applications of topology). Here’s an example:

[tony612]

@mbostock Thanks. I have tried to specify the projection as 'mercator', but it doesn't work well. Maybe there's something wrong as @wrobstory said.

I don't know if Vega support TopoJSON, this wiki only mentions the geoJSON

[jheer]

As @mbostock points out above, it appears that the GeoJSON file used above has an error in it, which should explain the undesirable behavior.

In addition, commit c77bd25 fixes Vega's geopath to use mercator as the default (as stated in the spec documentation). Thanks for catching the bug! Also, Vega largely inherits D3's extensive geographic mapping facilities. TopoJSON support has not been tested, but we will do so soon.

[tony612]

@jheer Is there something wrong with the GeoJSON file in the Vega's live editor?
In this editor, http://trifacta.github.io/vega/editor/index.html?spec=map, If you change the projection to mercator, you can see the same bug.

[jheer]

The problem you are seeing is an albersUsa projection being used by accident. This was fixed in my earlier commit. However, the fix has not been posted to the live website yet. If you run the Vega editor locally using the most recent version in the repo, you'll see that geopath with mercator projection now works correctly.

[tony612]

@jheer Thanks, it works normally. It's my mistake :)