The Map Area controls within the Main Window of DatMapR define the range of grid coordinates covered by the map. These can further constrain the selection of records to be mapped, and if no records fall within the specified range, no map will be produced.
If the Project is based on OS NGR (as flagged in the Project / Data Management window), the Map Area can be defined by entering the OS NGR values for opposite corners of the required map. (If the Project is NOT based on OS NGR, this option is not enabled.)
Alternatively (or if not based on OS NGR) the Map Area can defined by a range of Eastings and Northings Coordinates. The
example shown here is the recordeing area of the Sorby Natural History
Society base in Sheffield (UK) and was used in several of maps shown on the Example Maps
page.
As a further alternative, the Set Map Area to include All Data button will set the Map Area to include all data found for the selected data field based on the defined selection constraints. These values can be used as they are presented, or as a reference for defining a more specific area.
The Check Selected Data for the Map Area button will show a summary of the data selected for the specified area and aggregated as necessary.
In 'grid' mode, the map area limits will be adjusted 'outwards' by DatMapR to be exact multiples of the Grid Size. This will be done when the map is being formatted or when the Set Map Area to include All Data or Check Selected Data for the Map Area buttons are pressed.
In 'grid' mode, when the map is produced, the upper limits are omitted from the selection of data (logically these values would be mapped into squares outside the map area), while in 'exact' mode they are included.
In 'exact' mode the E/N values given are used for the data selection, but the displayed map area will be drawn slightly larger to accommodate symbols for data points at the very edge of the area.
