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The rasterization model is a part of Overlay models, that is tasked with converting attributes from features, from various layers, to values in rasters.
The rasterization model is a part of the [[Simulation Core]], that is tasked with converting attributes and polygons from features of various layers into raster values.


=Layers=
=Layers=
The layer rasterization sequence of the features is:
The layer rasterization sequence of the polygon features is:
# [[Net Line]]s
# [[Net Line]]s
# [[Address]]es
# [[Address]]es
Line 13: Line 13:
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:  
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:  


[[File:Raster outline.jpg|thumb|none|300px]]
[[File:Raster outline.jpg|thumb|none|300px|Outline rasterization method]]


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:  
However this will create a small overshoot resulting in larger cell area than the original polygon. To correct for this one could also rasterize based on the center point. As displayed below:  


[[File:Raster center.jpg|thumb|none|300px]]
[[File:Raster center.jpg|thumb|none|300px|Center rasterization method]]


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.
While more accurate, this method may fail for objects smaller than the grid cell area. If the cell center point misses a small object, it won't be rasterized and remains as traversable space in 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.
To compensate for this situation the default option is '''combined''' center + outline. This method uses center-point rasterization for most objects and outline rasterization for small ones to ensure coverage.


Via the the editor [[Calculation panel]] the rasterization method can be selected.
Via the editor [[Calculation panel]] the rasterization method can be selected.


* '''Combined''' Center for large and Outline for small polygons (default).
* '''Combined''' Center for large and Outline for small polygons (default).
* '''Outline''' Overshoot results in more cells then polygon area.
* '''Outline''' Overshoot results in more cells than polygon area.
* '''Center''' WARNING: fastest but missing small polygons.
* '''Center''' Fastest but missing small polygons.


Note: Since version 2025 'combined' is the default, before that Outline was used.
Note: Since version 2025 combined is the default, before that outline was used.
 
[[File:rasterization.jpg|thumb|none|500px|Select rasterization method in calculation panel]]
 
{{article end
|seealso=*[[Grid Overlay]]
* [[Rasterization (Average Overlay)]]
* [[Rasterization (Combo Overlay)]]
* [[Rasterization (Distance Overlay)]]
* [[Rasterization (Sight Distance Overlay)]]
|api=* [[Api session event editor setting set rasterization]]
}}

Latest revision as of 09:04, 14 July 2026

The rasterization model is a part of the Simulation Core, that is tasked with converting attributes and polygons from features of various layers into raster values.

Layers

The layer rasterization sequence of the polygon features is:

  1. Net Lines
  2. Addresses
  3. Buildings
  4. Terrains
  5. Areas
  6. Neighborhoods

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:

Outline rasterization method

However this will create a small overshoot resulting in larger cell area than the original polygon. To correct for this one could also rasterize based on the center point. As displayed below:

Center rasterization method

While more accurate, this method may fail for objects smaller than the grid cell area. If the cell center point misses a small object, it won't be rasterized and remains as traversable space in the simulation.

To compensate for this situation the default option is combined center + outline. This method uses center-point rasterization for most objects and outline rasterization for small ones to ensure coverage.

Via 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 than polygon area.
  • Center Fastest but missing small polygons.

Note: Since version 2025 combined is the default, before that outline was used.

Select rasterization method in calculation panel

See also

API Endpoints

Retrieved from "https://support.tygron.com/w/index.php?title=Rasterization&oldid=91369"