AGG line-join:round triangle artifacts bug testcase

14_10083_6161.vector.pbf.z

README.md

Setup

npm install

Use Mapnik 2.3.x branch at https://github.com/mapnik/mapnik/commit/68aaec5ac705791d59a410b0c21d335fa1985c63

Optionally use mapnik-vector-tile branch to reduce the testcase futher: https://github.com/mapbox/mapnik-vector-tile/compare/offset-debug

Running

node test.js

Results

out.png will have a black triangle artifact in the upper right

out2.png likely will not (for unknown reasons)

json.xml

<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over" maximum-extent="-20037508.34,-20037508.34,20037508.34,20037508.34">

<Style name="contour">
  <Rule>
    <Filter>[ele]=2330</Filter>
    <LineSymbolizer stroke="#000000" offset="1" clip="false" stroke-width="1" stroke-linejoin="round" />
  </Rule>
</Style>

<Layer name="contour"
  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
    <StyleName>contour</StyleName>
    <Datasource>
        <Parameter name="type">ogr</Parameter>
        <Parameter name="file">merc.json</Parameter>
        <Parameter name="layer">OGRGeoJSON</Parameter>
    </Datasource>

</Layer>

</Map>

merc.json

original.xml

<Map srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over" maximum-extent="-20037508.34,-20037508.34,20037508.34,20037508.34">

<Style name="contour">
  <Rule>
    <Filter>[ele]=2330</Filter>
    <LineSymbolizer stroke="#000000" offset="1" clip="false" stroke-width="1" stroke-linejoin="round" />
  </Rule>
</Style>

<Layer name="contour"
  srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over">
    <StyleName>contour</StyleName>
</Layer>

</Map>

out.png

out2.png

package.json

{
  "name"          : "vtile-test",
  "main"          : "./vtile-mem.js",
  "dependencies"  : {
      "mapnik":"1.4.x",
      "queue-async":"*",
      "bytes":"*"
  }
}

test.js

var fs = require('fs');
var zlib = require('zlib');
var bytes = require('bytes');
var mapnik = require('mapnik');

mapnik.register_default_fonts();

function vtile() {
    var map = new mapnik.Map(256,256);
    map.loadSync('./original.xml');
    var filename = '14_10083_6161.vector.pbf.z';
    var data = fs.readFileSync(filename);
    zlib.inflate(data, function(err, buf) {
        if (err) throw err;
        var parts = filename.split('_');
        var z = +parts[0];
        var x = +parts[1];
        var y = +(parts[2].split('.')[0]);
        var vt = new mapnik.VectorTile(z,x,y);
        vt.setData(buf);
        var im = new mapnik.Image(256,256);
        vt.parse(function(err) {
            if (err) throw err;
            fs.writeFileSync('out.json',JSON.stringify(vt.toGeoJSON(1),null,1));
            vt.render(map, im, {buffer_size:0}, function(err,image) {
                if (err) throw err;
                image.save('out.png',"png24")
            });
        }); 
    });
}

function normal() {
    mapnik.register_default_input_plugins();
    var map2 = new mapnik.Map(256,256);
    map2.loadSync('./json.xml');
    map2.extent = [4625357.4555925857275724,4965349.357405048795044,4627803.4404977113008499,4967795.3423101771622896];
    map2.render(new mapnik.Image(256,256),function(err,im) {
        if (err) throw err;
        im.save('out2.png',"png24");
    });
}


//normal()
vtile()