TCA uses a free software application, Map Maker Gratis, to map the Little Millhams site and the excavations. Exact geographic coordinates for on-site structural features and adjacent buildings have been obtained by identifying these same features in the satellite images available from Google Earth; the Google Earth coordinates for these features have then been used to align our map with the Ordnance Survey grid (after first transforming the latitude/ longitude coordinates used by Google Earth to the UK’s OS grid). A final sanity check against a paper OS map is used to verify that the calibration is not wildly in error: it is believed that the map alignment is accurate to within one or two metres.
Map Maker Gratis allows image files in formats such as jpeg or tiff to be superimposed and aligned with the map. We have used this feature to record aspects of the excavation by producing plan-view photographs or scaled drawings which are then placed on the map after they have been rotated and scaled correctly to fit in with the grid. Map Maker Gratis allows scaled prints to be produced, which are useful for on-site use; the accompanying image when printed out at A4 size, shows the site at a scale of 1:100.
The mapping is in a process of continuous refinement and development as new phases of the excavation are added. A working version of the current Map Maker Millhams project folder is available on Dropbox. TCA members who wish to may view the current status of the project by first installing Map Maker Gratis and applying to the TCA Secretary for access to the shared folder on Dropbox.