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file Modifica Elemento Impostazoni Shumenti Vane Area dilavoro Applicazioni Finestra 2 
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Figure 2. 3D representation of 1:500 map of Pavia town 
3. LASER DATA PREPARATION 
The Laser data has been acquired with a Toposys instrument on 18/11/1999, the flight height was about 850 mt 
In this way it was possible to have an planimetric accuracy of about +/-10 cm. and an altimetric accuracy of 
about +/-5 cm. Both the RAW-data (related to the DAT-last pulse, FAT-first pulse and QAT mode, cross-stripe) 
and 1 Mt Regular GRID data has been delivered. The second one (GRID data) is a sub-set transformation of 
the RAW data. 
In this paper only the GRID data has been taken under examination postponing the use of RAW data into other 
future paper; those (RAW) data are certainly much more (as number of points) than the GRID one and perhaps 
more accurate: in fact in one square meter usually many distances are calculated from the aircraft to the ground. 
The regular GRID data has been imported into MODELER software (by Intergraph) in order to create a DTM 
based on triangles. With this software it has been possible to analyse the data and to produce outputs such as: 
Sections, Assonometry, 3 D vision, etc. An example of GRID data representation is shown on Fig. No.3. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000. 135