o paper chart, or colour separations 
(repromats); 
o Scanning parameters: 
v Type of scanner: liner, flat bed, 
drum; 
Y Colour depth: paper charts are 
usually scanned in true colour 
while colour separation are 
scanned in b/w; 
Y Resolution: typically comprised 
between 200 dpi and 400 dpi. 
v 
o The bitmap is typically stored in a 
standard format . bmp; 
o Bitmap processing — colour reduction 
(the number of colours of bitmap is 
reduced to 4-bit colour depth). If 
repromats have been scanned, the proper 
colour is assigned to each of them; 
Y Georeferencing; pixel coordinates are associated to 
geographic coordinates (latitude, longitude) by ( 
means of control points with known coordinates; 
Y Normalization consists of rubber-sheeting the 
bitmap, to correct deformations possibly existing in 
the source documents or introduced by the scanner. 
The normalization result is storaged in format . bp CO owefshpot.. 
for creation of vector data in specialized software 
dKart Editor. Co-registration of repromats is also 
performed at this stage; 
  
Y Raster to vector conversion; vector data is created 
by appropriate software tools, such as: Line 
Following (LF) algorithms, Optical Character 
Recognition (OCR) algorithms, topological engines 
ete (Fig. 2); 
) 
"-— Convert / 
Raster pixels 5 
C) N / 
  
X 
_ Vector data \ 
"(Punta \ 
(09) 9 \ 
— Paraíso 
  
Figure 2. Raster to vector conversion 
Y Chart Compilation: 
o Structure the chart data into different 
‘layers’: 
Y Chart border, title, compass 
rose, eic.; 
Y  Depths, symbols, names, etc.; 
84 
D. gap/undershoot 
4. 
Y Depth contours, coastline, any 
features related to colour fills, 
etc (CARIS, 2000); 
o Vector electronic charts can be compiled 
from multiple sources: 
Y Data obtained by vectorization 
can be merged with data from 
other vector charts; 
Y . Vector data can be imported 
from databases (list of lights 
etc); 
Topological editing: 
o All digitized data contain errors (gaps, 
overshoots, duplicated data, missing 
labels etc), topological processing 
removes these errors (Fig. 3);the result of 
vectorization is a vector electronic chart 
with data classified into classes and 
encoded in form of features (objects). 
missing 
C) label 
  
Figure 3. Topological editing 
Validation and quality control (QC); Main criteria 
in quality control is navigational safety. Data has to 
be full (all necessary information is presented) and 
correct (both formally and logically); 
Printing the paper Nautical Chart with dKart 
Publisher (direct colour plot, postscript file, EPS 
file, CMYK colour separate files); Updating the 
Charts (assemble new survey data, extract data for 
the chart area, transform to the correct projection, 
scale, ellipsoid, etc., merge new data with the old 
chart). ENC should contain actual and up-to-date 
information describing the hydrographic situation 
at sea. Corrections are issued in a form of ER files 
(update). Update is relatively small pieces of 
information (only correction information is 
included) that have been aplied to the base cell. 
Bring it to the up-to-date level (IMA, 2001 & IMA, 
2002). 
CURRENT SITUATION IN PRODUCTION 
OF ENCs IN CROATIA 
HHI is a scientific and research institution responsible for the 
safety of navigation in the Adriatic, hydrographic survey, 
marine geodesy, design and production of charts and nautical 
publicati 
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