U radu se iznose mogućnosti novog načina izučavanja strukture sastojina na primjeru digitalizacije krošanja i izrade digitalnog trodimenzionalnog modela sastojina (vizualizacije). Kao podloga za to, uzete su dvije naše karakterističe prirodne mješovite sastojine, sastojina hrasta lužnjaka i običnoga graba (Carpino betuli-Quercetum roboris, /Anić 1959/ emend. Rauš 1969) te sastojina bukve i jele (Omphalodo vernae-Fagetum Marinček et al. 1992).
Na pokusnim plohama trajnoga karaktera sva su stabla obrojčana i kartirana,
a istima su izmjereni prsni promjeri, visine stabala, dužine debala te snimane horizontalne projekcije krošanja. Projekcije krošanja zatim su digitalizirane u CAD programu MicroStation, aplikacija IRAS B, sa srednjom točnošću od 4 cm. Samo geokodiranje i izjednačenje obavljeno je Affinom transformacijom (projiciranje koordinate iz jedne ravnine-izvorni koordinatni sistem, u drugu paralelnu ravninu-izlazni koordinatni sistem) te prebacivanju rasterskog file-a u vektorski oblik, također u programu MicroStation. Na vektorskim plohama izračunate su površine bez zastora krošanja unutar područja (plohe) te površine pod krošnjama izvan područja (plohe). Zatim su datoteke transferirane u program AutoCAD 2000 dwg zbog pojednostavljenog načina prikazivanja. Projekcije krošanja upotpunjene su vertikalnim profilom (CorelDraw) sastojine koji proporcionalno prikazuje odnos osnovnih elemenata krošnje i debla. Na temelju izmjerenih dimenzija stabala na terenu i računalnim programom 3DS Max napravljen je trodimenzionalni model sastojine. Modelu je pridružena odgovarajuća tekstura krošanja, čime se dobio slikovitiji prikaz situacije. Kod izradbe modela vodilo se računa o prostornom rasporedu stabala, visinama stabala, dužinama debala, dužinama i širinama krošanja te o fenotipskim oblicima krošanja hrasta, graba, bukve i jele.
U sastojini hrasta lužnjaka i običnoga graba simuliran je naplodni sijek te isti prikazan u trodimenzionalnoj naravi. Modeli omogućuju računalno praćenje i simulaciju obavljenih gospodarskih jera u sastojini i otvaraju nove mogućnosti rješavanja i upravljanja postojećim informacijama, a svoju primjenu mogu naći u aerofototaksaciji i GIS-u. Metode trodimenzionalne vizualizacije mogu poslužiti predočavanju prirodnog razvoja sastojina, vizualnoj usporedbi sastojina prije i poslije zahvata, kao i pomaku paradigme (primjera-obrasca) istraživanja u šumarstvu od promatranja cijele sastojine prema pristupu istraživanja pojedinog stabla.The paper presents the possibilities of a new method for the study of stand structures by crown digitalisation and production of a three-dimensional model of stands (visualisation). An investigation was carried out in a natural mixed stand of Peduncled oak and Common hornbeam (Carpino betulli-Quercetum roboris, /Anić 1959/ emend. Rauš 1969) and in a beech and fir stand (Omphalodo vernae-Fagetum, Marinček et al 1992). On experimental plots of permanent character all trees were marked by numbers and mapped, and d b h, tree heights and stem lengths measured and horizontal crown projections recorded. Crown projections were then digitalised in the CAD programme MicroStation, application IRAS B with mean accuracy of 4 cm. Geo-coding and functions of equation were performed by Affin transformation (coordinate projection from one plane-source coordinating system into another plane-exit coordinating system) and by transforming the raster file into vector form; also in the programme MicroStation. On the vector planes without canopy within the area (plot) and surfaces under crowns outside the area (plots), were calculated. Data were then transferred into the AutoCAD 2000 dwg programme for the purpose of simplification of presentation. Crown projections were completed by the vertical profile (Corel Draw) of the stand, which proportionally shows the relation between basic elements of the crown and stem. A three-dimensional model of the stand was made based on the measured dimensions of trees in the field and by the computer programme 3DS Max. The corresponding texture of crowns was added to the model, which resulted in a clearer presentation of the situation. During construction of the model attention was paid to the spatial distribution of trees, tree heights, stem lengths, lengths and widths of crowns and phenotypical forms of crowns of oak, hornbeam, beech and fir. Seed - cutting was simulated in the stand of Peduncled oak and Common hornbeam and shown in three-dimensional form. The models enable computer monitoring and simulation of management measures in a stand and present new possibilities for solving and using existing information, and their application can be found in aerial-photography estimation and GIS. Methods of three-dimensional visualisation can serve for the presentation of natural development of stands, visual comparison of stands before and after intervention, as well as for the change of the paradigm (example-pattern) in forestry research from whole-stand observation to investigation of an individual tre
