Technical Tools and Instruments
Satellite images, such as those provided by Google Earth and others, can provide a good starting point for producing basic maps. Particularly for larger cities, high-resolution and regularly updated data are available. Since they can be combined and overlaid with basic online maps, as provided by OpenStreetMap, these images can provide sufficiently accurate information for documenting conditions on the ground, and for most basic planning tasks. Where necessary, they can be supplemented with information from other sources, such as UNOSAT or private commercial service providers.
When documenting the pre-conflict status, however, the available historical satellite images may not offer the necessary resolution and quality.
Existing cadastral maps showing the boundaries and ownership of land parcels and plots are the most accurate sources for preparing basic maps. For some historic city centres in the Middle East, such cadastral maps are available from previous cadastral surveys and registers. On the other hand, such maps have been regularly updated only in a few cases. They therefore provide historical snapshots rather than up-to-date information on actual ownership and plot structures.
In addition, useful cadastral maps and records may have been lost or destroyed during the armed conflict.
Building surveys on the ground
Building surveys need to be performed in order to obtain exact measurements in cases where cadastral maps are outdated, missing or destroyed, and satellite imagery with appropriate quality and resolution is not available.
Such surveys can be especially relevant in the case of important buildings or ensembles if they are not marked on pre-conflict plans or if their original plans and documents have been destroyed. For the purpose of producing basic maps, floor plans are sufficient. More comprehensive building surveys are generally needed only for documentation and archiving purposes, and when planning actual reconstruction or restoration works (see also damage assessment of historical buildings).
Geographical Information Systems
Ideally, all cartographic information should be integrated into a comprehensive geographical information system.
In cities where urban regeneration projects have already been implemented in the wake of a conflict, as in the Old City of Aleppo, cadastral maps may be available in digitised form or even as fully-fledged GIS.
Where such information is accessible, it can provide a good basis for producing accurate and up-to-date basic maps.