[GIS] How to apply Mapnik Zoom Level Styling via Leaflet Zoom Levels

leafletmapnik

I've setup a node mapnik server to render some tiles for polygons. The application I've built to call out to these tiles is in Leaflet

An example of a current mapnik styling rule is below

<Style name="pubLands">
        <Rule>
          <Filter>[simple] = 'blm'</Filter>
          <PolygonSymbolizer fill="#e3cc00"/>
          <LineSymbolizer stroke="black" stroke-width=".1"/>
          <TextSymbolizer size="5" fill="black" face-name="Helvetica Black Regular" halo-fill="#DFDBE3" halo-radius="1" wrap-width="20">[detail]</TextSymbolizer>          
       </Rule>
</Style>

Features within this rule are being styled at all zoom levels etc. I would like to only show labels at my map's zoom levels of 13+. How can I modify the style.xml to only label above a certain zoom level, in this case a Leaflet zoom of 13+?

Best Answer

Scale dependent rules need to be applied via min/max scale denominators. https://github.com/mapnik/mapnik/wiki/MinScaleDenominator

Converting mapnik scales to map scales requires a conversion. The table below is a good start http://wiki.openstreetmap.org/wiki/MinScaleDenominator

My example ended up working with something like below

<Rule>
      <Filter>[simple] = 'state'</Filter>
      <MaxScaleDenominator>170000</MaxScaleDenominator>
      <MinScaleDenominator>0</MinScaleDenominator>
      <TextSymbolizer size="5" fill="black" face-name="Helvetica Black Regular" halo-fill="#DFDBE3" halo-radius="1" wrap-width="20">[detail]</TextSymbolizer>
</Rule>
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