Map Layer Grouping Considerations

During a Geospatial Analysis, exposures can only be accumulated by a single GIS Layer, either a polygon vector layer or a raster layer. This means that a group can contain only one layer that is identified as an ECA layer (an accumulation layer). An ECA layer is identified by the value "EC" in the AvailableForAnalysisTypeCode column in the tSpatialDataset table. As a result, you cannot include two footprints, each with a value of "EC", in the same group. ExampleYou cannot include in the same group: two raster layers; two polygon vector layers; one polygon vector layer and one raster layer.

Touchstone will display an error message if you try to add a second "EC" layer to a group. ExampleYou want to include two layers in a tropical cyclone group, a windspeed footprint layer and a storm path layer. The windspeed footprint is imported as a GRID type with the analysis type code set to "EC", while the storm path is imported as a PATH type with the analysis type code set to "SPTL". If you try to import another windspeed footprint into the same group, with the analysis type code set to EC, Map Layer Import will display an error message.

For grouped layers, the group name displays the complete group of layers as a single entity in all places in a Geospatial Analysis configuration and in Map Layers (when searching on the Active Layers tab). The group is tightly bound, meaning that you cannot add only one group member (layer) to the Active Layers tab as a single layer. However, in a legend, you can see the individual layers that comprise a group and the symbology associated with each layer.

Usage notes

•       Groups should comprise layers with the same spatial data type. In particular, you should import each layer that is part of a group as:

•       An event layer if the group is an event group

•       A boundary layer if the group is a boundary group

•       A hazard layer if the group is a hazard group.

•       Do not mix spatial data set types within a group, that is, do not include boundary and hazard layers or hazard and event layers in the same group.

•       If a group is composed of all event layers or all hazard layers, the layers should all list the same peril. This ensures that the layers appear under the correct peril on the mapping menus.