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I am using the style editor in GeoServer to make some symbols for an OpenLayers based Web GIS solution. But I face a challenge when trying to rotate some symbols. I have a Point Layer that needs to be rotated based on the values in a field named "ROTATION".

This is fairly simple and I created the following SLD that do this:

enter image description here

But unfortunately the values in the rotation field is not providing the correct rotation (it might be radians or something)... so I get the following result in my Web GIS (it is the small black lines):

enter image description here

I wish the black lines to be perpendicular to the red and blue lines. I have calculated that I will get the right rotation using the formula: (360 - "ROTATION" + 90) / 360

At least it works when I calculate a new field on the feature class using MSSQL (where the layer is currently stored). Unfortunately I can't do the trick in MSSQL as the data are currently in production. So my question is - how do I get this formula to work on the field ROTATION in the SLD editor.

I am using GeoServer 2.10.

I have so far read that I might need something with "ogc:Literal"Formula"/ogc:Literal", but what should I write exactly.

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1 Answer 1

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Something like this should work, using the math operators - please note it is untested:

<Rotation>
    <ogc:Div>
        <ogc:Sub>
            <ogc:Literal>450</ogc:Literal>
            <ogc:PropertyName>ROTATION</ogc:PropertyName>
        </ogc:Sub>
        <ogc:Literal>360</ogc:Literal>
    </ogc:Div>
</Rotation>
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  • Thanks JimT. I tried your suggestion but when I insert your code my symbols go back to looking as if there has been no rotation set at all. Is it possible that I have to set some initial parameter in the start of the SLD script to make it work with the math operators? Or do you have other suggestions? I changed the lines with Rotation to se:Rotation to fit with the other parts of my script. And when I hit "Validate" it says "No validation errors"
    – Kristian Birchvald Jensen
    Commented Jan 18, 2017 at 12:27
  • If your rotation values are in degrees then dividing by 360 as per your above equation is going to result in a tiny rotation that is impossible to see. Can you confirm the maths? Note that angles are expected in degrees
    – JimT
    Commented Jan 18, 2017 at 13:39
  • I can confirm the math. No matter what values I put into the Literal boxes nothing happens. I get my (wrong) rotation shown above, when I have no literal statements, but as soon as I add these (no matter the values eg 360 or 2) my black lines go back to a symbol showing no rotation.
    – Kristian Birchvald Jensen
    Commented Jan 18, 2017 at 13:45
  • I have tested the code and the basic functionality works - point objects are rotated. If the Rotation field is in degrees then I'm afraid the maths remains suspect. What I do suggest is that you start basic build up from there to try and track where the error is. Start with this perhaps: <se:Rotation> <ogc:Literal>45</ogc:Literal> </se:Rotation>
    – JimT
    Commented Jan 18, 2017 at 14:10
  • 1
    Hi JimT. Of course you were right. I did some trial and error and thanks to you made it work with: <se:Rotation> <ogc:Div> <ogc:Sub> <ogc:Literal>450</ogc:Literal> <ogc:PropertyName>ROTATION</ogc:PropertyName> </ogc:Sub> <ogc:Literal>1</ogc:Literal> </ogc:Div> </se:Rotation> ... Apparently my math skills could need a fresh up ;) Thanks again!
    – Kristian Birchvald Jensen
    Commented Jan 18, 2017 at 14:15

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