I am trying to use the Set Z Value algorithm in QGIS Graphical Modeler. More specifically, I would like to set the elevations using values contained in a field in the input layer, but the elevations are not getting passed to the output.

I have tried connecting things as described in this post: Using Set Z-Values in QGIS Processing Modeler, but Modeler is not passing any elevations to the output.

I have created the [Vector Layer] and [Vector Field] inputs as shown in the post.

In the [Set Z value] algorithm dialog, I have tried:

  1. setting the [Input layer] type to [Model Input] and the value to my [Vector Layer], and
  2. setting the [Input Layer] type to [Value] and setting the value to the corresponding layer name.

When I run the model, it prompts me to select the appropriate elevation field, which I do. The model runs and produces a result, but the result is not elevated. Any thoughts?

Model DiagramSet Z SetupModel Dialog

  • I only can confirm this behaviour, but I have no clue as to why it is as it is.
    – Erik
    Commented Jan 7, 2021 at 13:03

1 Answer 1


In the Z value setting of the Set Z Value algorithm, set a Value (instead of a Pre-calculated Value).

The value starts with something like 0.000000.

Press the data defined override button, Edit... option. It will open the expression string builder. Write the following expression:

attribute( @ElevField )

  • Thanks Gabriel! That works wonderfully and helps me better understand the way Modeler works!
    – GSC_Mapper
    Commented Jan 11, 2021 at 16:07
  • You are welcome, GSC. Commented Jan 11, 2021 at 22:59

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