scanner 
  
  
graphic preproccessing 
| 
  
coordinate transformation 
& clipping window 
  
  
  
automatic graphic 
combination 
  
  
     
  
  
convert it to TIFF format 
and using Paintbrush to 
edit the thinning result 
  
  
automatic raster 
  
  
to vector conversion 
  
  
  
  
form a DWG file 
and using AutoCAD 
to edit 
  
  
  
  
  
automatic 
topology 
  
  
topology check 
and display 
  
  
  
topology rebuild 
  
  
attribute input 
| 
attribute editing 
area and arc length 
calculation 
area deduction of 
linear feature 
|. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
database set up 
| 
| | | | | ] 
data data data data data plotting 
addition || editting || inguriying | statistics | and Land 
and and table use 
delete updating output || map 
  
  
  
  
  
  
  
  
  
  
  
  
  
Fig. 2 Flow chart of the system 
730 
* Graphic preprocessing 
* Interactive graphic editing 
* Line thinning 
* Raster to vector conversion 
* Automatic topology 
* Area calculation 
* Arc length calculation 
* Database management system 
* System function call 
The above mentioned functions of the system are 
introduced in details as follows. 
Data Acquisition from Scanner 
In this software system we have developed many 
interface softwares for various kinds of scanning input 
devices, so at present it can support many kinds of 
scanners such as HP series scanner, SHARP scanner, 
IS series scanner, FSS series scanner, HI series scanner 
and Mecrotek scanner and so on, which are stored 
graphic file in one of the formats such as TIF, PCX, 
PIC, IMG and so on. Addtionally it can also support 
any kind of the CCD cameras, but if the CCD camera is 
used for graphic input device, binarization and data 
compression must be done before using this software 
system to process. 
Automatic Graphic Combination 
Because scanners are different, the scanning sizes 
of scanners are also different. The minimum is A4 and 
the maximum is AO. The large size scanner can directly 
scan a full map sheet, but the small size scanner must 
scan the full map sheet block by block, so we developed 
an automatic graphic combination software. In order to 
do graphic combination, four control points are need to 
select in each block, and then each block separately car- 
ry out its coordinate transformation (include displace- 
ment, rotation and scale transformation), after the co- 
ordinate transformation and window clipping they can 
be combined two by two. The scheme of the automatic 
combination of two blocks is shown in Fig. 3. There- 
fore using graphic combination can digitize the full sheet 
map with small size scanner. 
  
  
  
  
  
  
  
  
  
Q4 Qe 
X A 
a, a 
b 3 ; 
b, 5 
Fig. 3 Scheme of graphic combination