How to view and edit projection details

A map projection is a method for taking the curved surface of the earth and displaying it on something flat, e.g. a computer screen. Certain GIS datasets are associated to a single map projection. These data are either embedded in the main data file or the main file is accompanied by a projection setting file, e.g. a world file.

For these data types to display in the correct location the viewing software has two options:

• It can be set to the same projection – in this case the data can be displayed “as is”.

• It must convert the data file to the projection of the viewer.

Note: Some projects may have datasets that use different projections, so in this case some data conversion will always be required to display all data correctly together.

Flood Modeller provides both options. There are advantages and disadvantages related to adopting either one that are detailed here.

New projects will initially be assigned the map projection specified in General Settings. The default setting here is the British National Grid (OSGB 1936), but this can be changed.

Current projection settings can be confirmed at any time from the ‘Info’ tab of the ‘Start’ tab.

Click Set Projection to edit the current projection.