I understand transforms on data that matches to OS MasterMap and Land-Line detail, but how do we accurately move data with no association?
In reality, all data mapped against or over Ordnance Survey large scale data will have an association. The difference is that where as some data may exactly match features depicted by Ordnance Survey, other information may just be relative to features. This relationship may be precise (one metre from the edge of a road) or may have a more flexible accuracy (between the boundaries of a carriageway). How accurate the data was before will have a bearing on what type of transformation you choose. In discussions with software suppliers, it is important that priorities are set between the relative accuracy and geometric fidelity (ensure that the network is straight and smooth whilst keeping it within the bounds or the pavement).
