Issue displaying to layers using XML stylesheet

[rheh]

I'm trying to use mapnik to draw a line path over a layer of countries. The problem I'm having is that both work on there own, but, not together. Here is my style:

<?xml version="1.0" encoding="UTF-8"?>
<Map srs="+proj=lcc +lat_1=49 +lat_2=44 +lat_0=46.5 +lon_0=3 +x_0=700000 +y_0=6600000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs" background-color="white">

  <Style name="countries">
    <Rule>
      <PolygonSymbolizer fill="rgb(255, 228, 193)" clip="false"/>
      <LineSymbolizer stroke="rgba(77, 163, 148, 0.5)" stroke-width="1" />
    </Rule>

  </Style>

  <Style name="points">
    <Rule>
      <LineSymbolizer  clip="false" stroke="rgba(77, 163, 148, 1)" stroke-width="2" />
    </Rule>
  </Style>

  <Layer status="on" name="world">
    <StyleName>countries</StyleName>
    <Datasource>
      <Parameter name="file">../data/world_merc.json</Parameter>
      <Parameter name="type">geojson</Parameter>
    </Datasource>
  </Layer>

  <Layer status="on" name="routeLine" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
    <StyleName>points</StyleName>
    <Datasource>
      <Parameter name="file">../data/routepath.json</Parameter>
      <Parameter name="type">geojson</Parameter>
    </Datasource>
  </Layer>

</Map>

With both I get:

And if I remove the map layer from the XML I get:

Can anyone see where I am going wrong?

[talaj]

Are both input projections correct? Isn't the line path just too short compared to whole world?

[rheh]

Thanks - I think it is projection related - I spent a few more hours on it yesterday. If I remove the Lambert 93 srs from the map it works; however, it is this projection that I want - not mercator. The data in the countries json is that from the demo projects which I believe is merc projection; thus, I though putting the srs for Lamert 93 on the map would do the necessary transform. But it does n't.

This style-sheet work:

<?xml version="1.0" encoding="UTF-8"?>
<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" background-color="white">

  <Style name="countries">
    <Rule>
      <PolygonSymbolizer fill="rgb(255, 228, 193)" clip="false"/>
      <LineSymbolizer stroke="rgba(77, 163, 148, 0.5)" stroke-width="1" />
    </Rule>

  </Style>
  <Style name="points">
    <Rule>
      <LineSymbolizer  clip="false" stroke="rgba(77, 163, 148, 1)" stroke-width="2" />
    </Rule>
  </Style>

  <Layer status="on" name="world">
    <StyleName>countries</StyleName>
    <Datasource>
      <Parameter name="file">../data/world_merc.json</Parameter>
      <Parameter name="type">geojson</Parameter>
    </Datasource>
  </Layer>

  <Layer status="on" name="routeLine" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
    <StyleName>points</StyleName>
    <Datasource>
      <Parameter name="file">../data/routepath.json</Parameter>
      <Parameter name="type">geojson</Parameter>
    </Datasource>
  </Layer>

</Map>

However, as stated I above I was a Lamert 93 projection. How would I achieve this?

Thanks

Ray

[talaj]

Thanks for the info, I will try to reproduce it.

[rheh]

I can supply the geojson files if required?

[talaj]

Why are you insist on Lambert-93? According to spatialreference.org, Lambert-93 is designed for the area of France. I think using such projection for the whole world is not good idea and can cause distortion of geometries in such way they can fall off rendering bounds.

[rheh]

It's the preferred projection in the Aviation world Pilots use aeronautical charts based on LCC because a straight line drawn on a Lambert conformal conic projection approximates a great-circle route between endpoints for typical flight distances.

[talaj]

Yeah, it works well now, when I set srs of the world layer and rendering just bbox of Lambert-93 (-357823.2365, 6037008.6939, 1313632.3628, 7230727.3772):

<Layer status="on" name="world" 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">

Bigger bbox:

[rheh]

Many thanks for the assistance. Is this with the LLC projection on the map? As mine still only work with the merc projection on the map layer.

[talaj]

Is this with the LLC projection on the map? As mine still only work with the merc projection on the map layer.

Yes, this is complete style I have used:

<?xml version="1.0" encoding="UTF-8"?>
<Map srs="+proj=lcc +lat_1=49 +lat_2=44 +lat_0=46.5 +lon_0=3 +x_0=700000 +y_0=6600000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs" background-color="white">
    <Style name="countries">
        <Rule>
            <PolygonSymbolizer fill="rgb(255, 228, 193)" clip="false"/>
            <LineSymbolizer stroke="rgba(77, 163, 148, 0.5)" stroke-width="1" />
        </Rule>
    </Style>

    <Style name="points">
        <Rule>
            <LineSymbolizer  clip="false" stroke="rgba(77, 163, 148, 1)" stroke-width="2" />
        </Rule>
    </Style>

    <Layer status="on" name="world" 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>countries</StyleName>
        <Datasource>
            <Parameter name="file">world_merc.json</Parameter>
            <Parameter name="type">geojson</Parameter>
        </Datasource>
    </Layer>

    <Layer status="on" name="routeLine" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
        <StyleName>points</StyleName>
        <Datasource>
            <Parameter name="inline">
                wkt
                "LINESTRING(-0.260977596045 51.550861001, 2.33179584146 48.8514328748, 6.90210834146 50.9733894467, 13.4939052165 52.4972462654, 20.9646083415 52.2558018565, 27.4685145915 53.9959037304, 37.5759364665 55.7899327576)"
            </Parameter>
            <Parameter name="type">csv</Parameter>
        </Datasource>
    </Layer>

</Map>

[rheh]

Thanks @talaj it work just fine now.