A result type of a Grid Overlay indicates what output result from a complex calculation should be stored in that overlay. Since one calculation can often produce multiple types of (intermediate) results, result child overlays can be added to store these results. These result child overlays are always related to their result parent overlay. A result parent overlay always governs the calculation settings, such as the calculation model attributes and keys.
A number of overlays offer multiple result types.
Result Parent Overlay
Some Grid Overlays, such as the Water Overlay, perform complex calculations with multiple forms of input and intermediate steps, and possibly also multiple kinds of output. For these Overlays, a specific result type can be configured which indicates what information should be output when the calculation completes. For example, for the Water Overlay the result types include the surface last value result type and the groundwater result type for water above and below ground respectively.
Even though a calculation may calculate intermediate results as it progresses, or even a variety of end-results, only the results specified by the configured result type are stored. Other overlay results are not stored in that overlay.
Result Child Overlay
Generally, Overlays which offer multiple result types also offer the ability to add additional output Overlays, which are automatically linked to the calculation model, so that more different kinds of results can be obtained after the calculation completes. These are Result Child Overlays. They are automatically added as Child Overlays to the related calculation model. Otherwise, these Overlays function the same as other Overlays. They can be named, have their own legend and Attributes, and can be selected in the viewer interface. They can also be queried for their results, and exported.
The benefits of using Result Child Overlays rather than multiple individual Grid Overlays configured identically other than their result type, are:
- Only a single Overlay contains the configuration for the desired calculation. If multiple configurations have to be kept identical, the chance of a user making a mistake when making a change to the configuration is much greater.
- Only a single calculation needs to be performed. If multiple calculations need to run, even if they are configured the same, the waiting time for them all to complete would be greater for each added Overlay.
- When a Result Child Overlay has its result type changed, its legend is automatically updated (unless a custom legend is configured). However, the actual data is not immediately updated; The Result Parent Overlay the Result Child Overlay is related to needs to be recalculated.