I have a set of contours that I am trying to automate a process on. This process clips the contours by a boundary, sets z-values based on the elevation field, and then exports those contours as a dxf file to be used in CAD. My issue is that I cannot figure out how to set the Z-value from the Processing Modeler algorithm.

Is there a certain syntax that I need to use so that I can assign the "ELEV" field from the output of my clip function to the Z-value in the Set Z-value function? I see no drop down or option to select a field from the output of the clip function so I am confused as to how to accomplish this.

1 Answer 1


If you know the name of the field,
you can use an expression with the field name set as default, just select edit, and you'll get an expression builder window.

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Otherwise, you can use a pre calculated value and set it from a field you can connect to your selected layer

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The end result (just for this part) looks like this, where the Vector Field is connected to the Vector Layer and Set Z-Values uses them both.

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