This project was initiated and it is payed for by the investors to fulfill their needs in establishing a GIS which will enable them to assess the influence of the proposed Novo Virje power plant location on the environment. Existing maps 1:25000 (last time updated 25 years ago) were rectified,digitized and structured into a GIS database. Responding to the investor's request content was somewhat reduced (lonely trees,houses were left out, etc.). Updating of the map content was done using remotely sensed data from the russian KVR-1000 satellite (panchromatic,2 meters spatial resolution) using on-the-screen digitizing technique. This methodology has been chosen because it is the most rational way (less administrative hassle, cheaper) to update 1:25000 maps. Software used: ArcInfo 7.0.3. CPS 2.0 (Cartographic Production System) ERDAS IMAGINE 8.2.
In order to establish GIS for the Drava river a GIS project was
launched as a part of preliminary construction plans for "Novo Virje"
power plant and with primary goal to develop an environmental impact
study. Under that project GISDATA ltd. was assigned the task of
building unique topographic base to be used by the project investors and
for the future users. Topographic base should be used as a background
for different thematic layers needed in further project phases. During
the design of the vector part of the database for the project, he
intention was to develop coding schemes for the 1:25,000 map contents
which are to be entered into the database in several different ways of
digitizing. There were a few guidelines for accomplishing that: The
project will have several successive phases so the database has to be
flexible and easy to maintain, which means to add new layers of contents
and to remove the obsolete ones. In the Republic of Croatia the official
topographic-cartographic information system (STOKIS) was planned, but is
still not established. Therefore, during the database design period we
had to create our own attribute coding scheme. We tried to base the
elementary classification of the topographic content on German ATKIS
system, regarding that it is also basic foundation for the Croatian
STOKIS, which is still under design.The main data source for the
topographic base was the existing 1:25,000 scale military topographic
map, which was last time updated twenty and more years ago. Therefore we
insisted to create the object subgroups inside major object groups so
that they can be identified using symbol codebook associated with
topographic 1:25,000 maps. The most important sources for updating the
contents of the maps were KVR1000 and SPOT-XS satellite images.During
the database design phase and in the proces of creating the coding
system we considered the needs of the users and investors' request, so
we generalized some features already in the digitization phase. The most
obvious example of that was dropping out lonely trees and houses and
grouping houses in the settlements into blocks. As mentioned before, one
of the goal was to create a database with attribute coding very similar
to German ATKIS. Therefore, the whole topographic content was divided
into seven major object groups with subgroups. So, each object's code
contains group number, subgroup number and object type number. The map
contents were organized as seven main ArcInfo layers: coordinate
network (geodetic) points
settlements
communications
vegetation
water bodies
relief
(contour lines etc.)
administrative areas
Each of the layers
consists of line, polygon and point coverage, depending on the way
digitized contents are represented on the map. For example,
"COMMUNICATIONS" layer consists of line coverages (roads, railroads,
transmission lines, ...), polygon coverages bus stations, railway
stations, ...) and point coverages with traffic objects to small to be
represented as a polygon at 1:25,000 scale. Data was converted mannualy
using PC ARC/INFO and semi-automatically using on-screen vectorisation
in Hitachi Tracer for AutoCAD.Data was attributized and prepared in
ArcInfo coverage format. The content of the map was updated using
remotely sensed data from Russian KVR1000 and SPOT-XS satellite images
using on-screen digitizing technique. Final result is a topographic
database, convinient for overlaying with thematic data, environmental
impact analysis and plotting topographic thematic maps.
New satellite images with higher resolution gives new possibilities for using the technology as a source for updating topographic maps. According to demanded accuracy for the 1:25,000 scale we chosen Russian KVR 1000 images with two-meter resolution. The Drava river area is relatively flat, so there was no need for orthorectification.The image was geocoded using existing 1:25,000 maps. In order to update line features (railroads, roads, streams) the IMAGINE's edge EdgeEnhancement filter was used. Regarding the grey spectar of the image, width and shape of the line features, attributes were updated, too. For the "Forest area" theme we utilized Landsat TM and KVR 1000 integration, but that degraded the resolution to 3 meters. To the standard 7 spectral channels we added the eighth one called NDVI (Normalized Vegetation Index) for better differentiation between high scrub vegetation and young forrest. Integration of the two images were accomplished using Principal Component (PC) method, and after that EdgeEnhancement and Summary filters were applied. The existing coverage "FORREST" originally digitized from the topographic maps was used as the test area. Major differences among the old map (updated 1987) and the situation on the ground (KVR 1000 image is datet 1992) were explained as to be due to the long period changes and, even more, local agrar reforms carried out in the meantime.
Cartographic processing was done using ArcInfo ARCPLOT and CPS (CARTOGRAPHIC PRODUCTION SYSTEM, T-KARTOR, SWEDEN). Symbolsets were created in ARCPLOT and imported into CPS. CPS was used for all other cartographic operations, from data dictionary creation to creating ArcInfo metafile. Maps were plotted on HP755CM DesignJet plotter.
This metodology was chosen because it is the most rational way for updating topographical maps. However, in order to achieve full compilance with cartographic standards additional work should still be done (field work, etc..) In the Republic of Croatia there are some specific problems related to cartography. The most important for the theme being discussed here is that Croatia lacks reproduction originals for all topographic maps. The latter were under responsibility of former Yugoslavia's army, which turned into an agressor to Croatia. It is impossible for Croatia to get the cartographic materials even today. In the Republic of Croatia there are intensive activities under way to establish official topographic and cartographic information system and, as a subproject, to renew 1:25,000 topographic map. The project described here, conducted by GISDATA ltd., is the pioneering one towards determined goals.