Rasterization model
The rasterization model is a part of Overlay models, that is tasked with converting attributes from features, from various layers, to values in rasters.
Layers
The layer rasterization sequence of the features is:
Methods
Converting polygons to grid cells can be done in different ways. A common approach is by checking the intersection between the polygon outline and the cell. As displayed below:
However this will create a small overshoot resulting in larger cell area then the original polygon. To correct for this one could also rasterize based on the center point. As displayed below:
Although this provides a fairly accurate area this can lead to unwanted results for very small objects that are smaller then the grid cell area. When the cells center point does not intersect the small object it will not be rasterized and thus be part of the simulation.
To compensate for this situation the default option is combined center + outline. Where most objects are rasterized via the optimal area solution (center point) and small objects are rasterized with the outline to prevent falling of the grid.
Via the the editor Calculation panel the rasterization method can be selected.
- Combined Center for large and Outline for small polygons (default).
- Outline Overshoot results in more cells then polygon area.
- Center WARNING: fastest but missing small polygons.
Note: Since version 2025 'combined' is the default, before that Outline was used.