In the following CSS styling:

* {
   mark: url(smileyface.png);
   mark-mime: "image/png";
   mark-rotation: 45;

How can I make the URL value dynamic (to be read from a layer's field image_url)?

I've tried the following:

* {
   mark: url([image_url]);
   mark-mime: "image/png";
   mark-rotation: [rotation_angle];

But didn't work. The server console says:

WARN [renderer.style] - Unable to read image at file:/Applications/GeoServer.app/Contents/Java/data_dir/workspaces/tst/styles/%5Bdescription%5D : Can't get input stream from URL! 

The auto-generated SLD is:

                <sld:OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="[image_url]"/>

Although the same works for mark-rotation.

  • Does it work with mark: url(${image_url}); or mark: url('${image_url}');?
    – JGH
    Commented Mar 15, 2018 at 12:10
  • Thanks a lot JGH, mark: url('${image_url}'); works perfectly.
    – Faz B
    Commented Mar 15, 2018 at 12:32

1 Answer 1


In the SLD, you would need to use a CQL filter for the dynamic external graphic. One trick in CSS is to write this CQL filter as plain text that will later be interpreted in SLD.

* {
   mark: url('${image_url}');
   mark-mime: "image/png";
   mark-rotation: [rotation_angle];

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