UTFGrid from raster source

Question

Is it possible to make utfgrids from a raster source (e.g. GeoTIFF)?

I am trying to get utfgrids from a .tif with mapnik.xml and TileStache but it seems not to be working. As a workaround I am polygonizing the tif to a shape which works well but is not very efficient.

Has anyone experince with this question? Maybe with other tileservers?

This would be an example for the TileMill generated mapnik.xml I am working with:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Map[]>
<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">

<Parameters>
  <Parameter name="bounds">5,43,18,50</Parameter>
  <Parameter name="center">16.7693,48.4365,9</Parameter>
  <Parameter name="format">png8</Parameter>
  <Parameter name="minzoom">0</Parameter>
  <Parameter name="maxzoom">15</Parameter>
  <Parameter name="scale">1</Parameter>
  <Parameter name="metatile">2</Parameter>
  <Parameter name="id"><![CDATA[test]]></Parameter>
  <Parameter name="_updated">1409125380000</Parameter>
  <Parameter name="name"><![CDATA[tmp2m_2_grid]]></Parameter>
  <Parameter name="tilejson"><![CDATA[2.0.0]]></Parameter>
  <Parameter name="scheme"><![CDATA[xyz]]></Parameter>
</Parameters>


<Style name="utf_grid" filter-mode="first">
  <Rule>
    <RasterSymbolizer opacity="1" scaling="near"/>
  </Rule>
</Style>
<Layer name="utf_grid"
  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>utf_grid</StyleName>
    <Datasource>
       <Parameter name="file"><![CDATA[/path/to/test.tif]]></Parameter>
       <Parameter name="band"><![CDATA[1]]></Parameter>
       <Parameter name="type"><![CDATA[gdal]]></Parameter>
    </Datasource>
  </Layer>

</Map>