Bad negative area for Africa/Lubumbashi

[TwoClocks]

Firstly, this is great! I've been trying to figure out how to get territorial waters into the efele data set for a while, now I don't have to!

I downloaded the 2017a release, and I have some issues with the geoJson version of the data.

It looks like Africa/Lubumbashi has one negative polygon with only 4 points (3 if you don't count the dupe at the end), it also looks like it's area is 0. Also, the points go beyond 6 significant digits. Here is the json w/ a most of the points of the positive area removed for readability :

{
"type" : "Feature",
"properties" : {
"tzid" : "Africa/Lubumbashi"
},
"geometry" : {
"type" : "Polygon",
"coordinates" : [ [ [ 23.8940358, 4.8313928 ], .... a ton of points removed .... [ 23.8940358, 4.8313928 ] ], [ [ 24.4123887, -1.7179482 ], [ 24.440029068012333, -1.735314196891881 ], [ 24.440029068012333, -1.7353141968918806 ], [ 24.4123887, -1.7179482 ] ] ]
}
}

[evansiroky]

I'm not sure what you mean when you say that Africa/Lubumbashi has a "negative polygon". Can you explain what a "negative polygon" is and why it is a problem?

I do agree that having more than 6 significant digits is overkill.

[TwoClocks]

Sorry, I'm not sure I have the right lingo.

So, my understanding is that a geoJson polygon one "positive area" that outlines a region, and N "negative areas" that are entirely within the positive area and are subtracted from the positive area. Maybe these are called exterior/interior? Not sure of the correct terminology. For GeoJSON the first polygon is should be the positive area, and all the rest should be negative areas.

So in this case I'm talking about the second polygon in the list for Africa/Lubumbashi. It also looks like it as an area of almost 0. If you round to 6 significant digits it seems to describe a line.

Is that helpful?

[evansiroky]

ok, I see what you're talking about now. I think this particular negative area is an artifact of some geometry operations used to build this zone.