I've created a CartoDB map with a bunch of different multipolygons and it is displayed with a CartoCSS color ramp I created. However I've noticed that I cannot rid my map of the dashed lines that separate the polygons. I initially thought this was due to my polygons being mulitpart instead of singlepart, but even working with a singlepart polygon, I still get those dashed lines.

My CartoCSS has no mention of line-color, line-width, or line-opacity to it. I've also tried to specifically set the line-opacity and line-width to 0 in hopes that this would take care of it. Here is my CartoCSS:


Here's a screenshot of what I'm seeing

enter image description here

Here's a URL to my visualization: http://cdb.io/1Ig5cGq

It looks like what I'm seeing is actually slivers of the basemap behind the polygons. @andytilia's comment helped me find this. This is interesting because the polygons match up completely. Even when zooming in all the way the "gap" only appears to be a very faint dotted line.

Here's what I see on a dark map background:

enter image description here

Zoomed in all the way:

enter image description here

I'm wondering now if this is an bug in CartoDB or it's rendering engine Mapnik. Or perhaps there is something I need to do to my geometry (ST_Scale?) that I could use to "grow" my geometry by like a half meter and remove those lines?

  • Is there another layer involved? When I open your visualization first I see the shapes without the boundary for less than 1 second then the boundary (and maybe some transparency?) is added.
    – andytilia
    Commented May 6, 2015 at 15:47
  • There wasn't any other layers except for the map. Your idea of an additional layer though, led me to the idea that what I'm actually seeing is the map itself!
    – scud42
    Commented May 6, 2015 at 18:27

1 Answer 1


No geometry editing needed!

I was able to get around this by applying the same styling of the polygons to the polygon outlines as well.

  line-width:1; line-opacity:0.4;
  [fcst<=68]{polygon-fill:#DFF22C; line-color:#DFF22C;} 
  [fcst<=66]{polygon-fill:#BFE526; line-color:#BFE526;} 
  [fcst<=64]{polygon-fill:#9FD81F; line-color:#9FD81F;} 
  [fcst<=62]{polygon-fill:#7FCC19; line-color:#7FCC19;} 

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