Mastering QGIS - Second Edition

Adding data inputs to your model

In this first example, you will identify the portion of a forest within 100 meters from streams (riparian trees). To begin a model, you will need to define the inputs. The graphical modeler will accept the following:

• Boolean
• Extent
• File
• Number
• Raster layer
• String
• Table
• Table field
• Vector layer

To add an input, either double-click on the appropriate category from the Inputs tab or drag the input onto the modeler canvas. The Parameter definition dialog will open. Give the parameter a name and fill in any other details, which change depending on the input that is chosen. When an input parameter is defined and added to the model, it is essentially a conceptual parameter. It will not actually be connected to a GIS data layer ...