Millions of archaeological air photos have been made in the past, and many more will be made in the future. Each photo is a unique record which contains spatial information of historical value. It’s worth as a record depends on being able to find features on the ground and to protect them from destruction or for scientific study. Thus, the spatial data in the photography needs to be related to its position on a large scale map. The map in turn, is an abstraction and generalisation of the true appearance of the terrain, and it is based on a transformation of that appearance relative to the three dimensional shape of the Earth. The techniques for making such transformations, which are erroneously called ‘projections’ for historical reasons, have long been based on higher mathematics and hundreds have been invented during the long history of map making.
Showing posts with label Datum. Show all posts
Showing posts with label Datum. Show all posts
Wednesday, October 27, 2010
WHERE ON EARTH IS IT?
Millions of archaeological air photos have been made in the past, and many more will be made in the future. Each photo is a unique record which contains spatial information of historical value. It’s worth as a record depends on being able to find features on the ground and to protect them from destruction or for scientific study. Thus, the spatial data in the photography needs to be related to its position on a large scale map. The map in turn, is an abstraction and generalisation of the true appearance of the terrain, and it is based on a transformation of that appearance relative to the three dimensional shape of the Earth. The techniques for making such transformations, which are erroneously called ‘projections’ for historical reasons, have long been based on higher mathematics and hundreds have been invented during the long history of map making.
Subscribe to:
Posts (Atom)