Characteristic
features of the cartographic documents:
-
the
cartographic documents can be stored in 2D or 3D form
-
the
2D cartographic documents can be single sheets or series of sheets; they can,
however, be bound in volume(s), too. They are regularly coloured, use tiny
signs (small letters of 1 mm in size or graphic sings in this size).
-
their
dimensions are changing, often larger than A0 (70x100 cm). Paper, paper mounted
on linen, parchment, silk etc. can be as their supporting materials.
-
they
have determined mathematical structure; indexes or other data collections can
be attached to them
Digitising
is connected with their features and their size:
a.
directly:
-
with
scanner
-
with
camera scanner
b.
indirectly:
-
using
traditional photograph (slide) in size of 6x7, 9x12, 13x18 cm etc. The slide is
used at scanning in this case.
The
quality of automatic retrieval of the indexes, data collections is not the
required one, especially at the case of old maps. These data need to be stored
manually in databases.
For
further processing of the digital data set, the vector format would be the best
solution, but data sets only in raster format are being built recently. The
memory demand of a digitised, coloured map in size A0 reaches 700 MB.
Conservation
of the cartographic documents can be successfully solved using digitising
technology these days.
Such
a high data set can hardly be processed by a PC, the access to it on the
internet is unsolved.
Recently
using packing procedures causing no losses can solve this only. The best of
these is the Mr.SID program, although lots of image processing programs do not
support it.
The
Internet service of large data sets needs server with high capacity; without
owning such a server this service of the National Széchényi Library can be
accessible via an external server.
An
other problem for the users is the significant difference between the monitor's
size of the PCs and the sizes of the maps what difference causes that the user
can see only a part of the map on the screen. At web service a small guiding
outline of the maps can considerably enlarge the size of the data set.
A
special problem can be if the cartographic documents are accessible in an image
database. For this reason the AMICUS database of the Széchényi Library was
previously connected via URL, now via URN. Using this technology the user of
the library's data set can also access
the digital image of the cartographic document immediately.
This
solution is quite new, also internationally.