104 
models result In geometric accuracy about 7 
m in plane and 11 m in height. Much better 
accuracy can be obtained when using the 
new Dutch airborne system CAESAR develo 
ped by the Nationaal Lucht-en Ruimtevaart- 
laboratorium. Its resolution corresponding to 
2 km altitude is 0.5 m x 0.5 m. 
The advantages of remote sensing technology 
offer a wide range of possibilities for LIS/GIS. 
The new area of research emerges linking 
LIS/GIS and remote sensing. The research 
includes: 
- integration of remote sensing data with 
existing topographic data; 
- use of high resolution imagery in LIS/GIS 
processes of data capture and updating, 
including processes of topographic map 
ping; 
- application of expert systems methodology 
to spatial identification of objects using all 
available information on them. 
3.3.1 Vectorization and interpretation of the 
scanned map data 
At present the majority of the spatial data for 
LIS/GiS systems are coming from conversion 
of existing maps into vector form. Manual 
methods of this conversion procedure use 
well known digitizing tables and are extremely 
tedious requiring steady concentration of the 
operator. 
Most of the automatic digitizing methods are 
based on map scanning which produces 
raster data as arrays of pixel values. The 
scanning is followed by: 
- raster to vector conversion, which is a 
process which can be automatized; 
- vector data interpretation and geometric 
improvement; this process can probably not 
fully be automatized and normally involves 
time-consuming editing. 
The technological progress implies that auto 
matic digitizing will be widely used in the near 
future. 
* 
The research focuses on: 
1. Manual digitizing on the screen. In this 
method raster data are displayed first. The 
image visible on the screen is digitized 
manually using screen cursor and recor 
ding vector data point, object after object. 
This approach offers interesting advan 
tages. Use of a digitizing table is avoided. 
The operator can concentrate his attention 
on the display as a single input/output 
device. Thus, input and output of graphic 
functions are combined, creating such 
possibilities like immediate overlay of raster 
and vector data for checking and control 
ling progress of the work. 
2. Improvement of vectorization. Software for 
vectorization delivered by producers of 
scanning systems do not satisfy users who 
require results of specified high quality. 
Two approaches are considered: 
- development of a new vectorization 
system based on algorithms gives better 
results, especially when scanning large 
scale maps; 
- development of a post-processor which 
improves consistency and accuracy of 
vector data produced by commercially 
available vectorization software. 
3. Interpretation of vector data. Automatic 
creation of objects and their recognition by 
assigning classification codes is an impor 
tant problem which needs investigation 
using methodoiogy related to expert sys 
tems and artificial intelligence in general. 
3.3.2 Computer aided surveying 
The project implies the further development of 
a system for 3D Computer Aided Surveying, 
using Scanned PAnoramic Registrations 
(CASSPAR). This is a new system for collec 
ting, processing and presenting detailed 
geometric and topographic data, based on a 
new method for measuring and calculating 
co-ordinates, for which a patent is applied. 
CASSPAR substitutes surveying measure 
ments outdoors by measurements indoors 
using 360 panoramic images recorded 
photo-graphicaliy (electronic recording is 
planned). Moreover the system allows to 
optimize the number and geometric 
configuration of measurements during the 
measurement process. In this way it will be 
possible to come to optimum results 
interactively, using a computer. Thus not only 
a new method for rapid mapping becomes 
possible, but also the possibility is created to 
present dynamic three-dimensional images or 
simulations: optical and/or digital "movie map". 
CASSPAR consists of a mobile (recording) 
part and a stationary (measurement, 
calculation and display) part. At the moment, 
as a result of a completed research project, a 
first prototype of the optics of the mobile unit 
and a complete stationary unit are available.