Over recent decades farmland abandonment has affected large areas of the landscape. To better predict the changes associated with this process, we developed a secondary succession model based on Ellenberg indicator values describing the ecological niche of a tree along environmental gradients. These values are compared with local ecological factors dependent on terrain conditions. The terrain is represented by a Digital Terrain Model, where the local conditions are represented by a light availability model, climate data, soil properties, and a combination of a water flow model and average annual rainfall data. Each tree in our model is associated with its immediate circular ecological neighbourhood and is treated individually from the seedling stage through to its decay. Each year, tree heights, actual vigour, and neighbourhood radii were calculated. When two radii intersected, the vigour of both trees was compared. The weaker of the two became dominated, leading to stress-related mortality. When a tree reached the adult stage, it produced seeds that established new seedlings that competed for light and nutrition. To start the simulation, the initial amount of seed was planted on bare ground. It was possible to monitor the succession phases either visually or statistically. 3D tree models were used to visualize a tree at any age, generating realistic landscape images useful for demonstrating long-term changes in the cultural landscape to non-experts. The results were compared with those from previous field studies in various areas of Slovenia. Apart from predicting landscape changes after farmland abandonment, the model can be used for forecasting the regeneration process after clearcutting or natural disasters. (c) 2014 Elsevier B.V. All rights reserved.

Fire-fighters work under extremely stressful conditions where even their own lives and the lives of potential victims can be at stake. It is clear that there is no room for error and that extensive training is crucial in this regard. In Slovenia the greater part of the fire-fighting force consists of volunteers, whose training must be of the same quality as that of their career colleagues. Fire-fighters receive the bulk of their basic training in-house at their fire departments and by assisting at actual fires. More advanced training is received at special training facilities where the training is divided into a series of relatively short courses consisting of both theoretical and practical parts. This training culminates in a practical exam aimed at demonstrating their acquired knowledge. This article presents a new multimedia-based teaching tool SIN that has been designed for computer-supported theoretical knowledge delivery during fire-fighter training, where the emergency operations are visualised within environments familiar to the trainees. In order to save time the entire scenario is based on photographic images of real places. This application has already been successfully tested and is currently in use by the fire-fighter school at the Administration of the Republic of Slovenia for Civil Protection and Disaster Relief.

The problem of optimal team formation is domestic to many areas of work organization including education, sport, and business. It is beyond manual implementation to build near optimal teams as soon as the pool of available personnel grows into several tens. The selection process itself is usually well defined - for each team we construct the criteria relating to the required properties (i.e., capabilities) of the team members. Because these properties can be arbitrarily combined in the personnel, the objective function becomes self-conflicting. This aggravates the team formation and calls for a specialized software support. In the paper we present a new fuzzy-genetic analytical model for the problem of project team formation. It builds on previous quantitive approaches, but adds several modeling enhancements like derivation of personnel attributes from dynamic quantitive data, complex attribute modeling, and handling of necessary overcompetency. We improve the flexibility of requirements specification using a special format that expresses the required team capabilities using fuzzy descriptors. We then define a single compound objective function, which incorporates multiple opposing criteria that the solution should maximize. To optimize the selection of multiple project teams with possibly conflicting requirements, we propose a special adaptation of island genetic algorithm with mixed crossover where the fitness of common solution is used to drive the selection within the islands. We test the effectiveness of the system using artificial domains of different complexity and describe some practical experiences of using the system in the educational process.

Various blending functions can be applied in the volumetric modelling of clouds. This paper analyzes the impact of five different blending functions (linear, cubic, Wyvill-1, Wyvill-2, and cosine) on cloud shape, structure, and area. We have found that there are only negligible differences among them. Therefore, we can conclude that the simple linear blending function satisfies all the desired properties for generating cloud images by volumetric modelling.

In the paper, we present a new architecture and implementation of a multi-agent system for university timetable generation. Agents as representatives of individual courses have the task of allocating the necessary human and technical resources through negotiation. We define the negotiation protocol and describe autonomous decisions of agents within the prescribed framework. The advantages of the multi-agent approach are a direct resolution of conflicts, strategic versatility of negotiation, and natural representation of some real-life problems.

In this paper, we present a new efficient algorithm for reconstruction of nonintersecting 3D curves from a sufficiently dense sample. We use the Euclidean minimal spanning trees to identify line segments reconstructing curve shapes. To deal with more than one curve in a sample and to eliminate noisy data, we introduce chains of connected line segments. With the incremental growth based on heuristics, the chains contain finally curve shapes. The method is robust and fast for both 2D and 3D curves.

Parametric curves and surfaces are topics usually included in different disciplines, such as computer graphics, geometric modeling, computer-aided design (CAD), computer-aided geometric design (CAGD), etc. These rapidly emerging and extensive fields require students to understand a wide range of methods. In this context, SURFMOD, a teaching tool for parametric curves and surfaces, was constructed. SURFMOD enables interactive investigation, different quality analyses, and simultaneous studies of various methods using the same data, while, at the same time, ad-justing the control parameters.

Current implicit blending techniques are mostly designed for use in surface modelling, where only boundaries of the object defined by the implicit primitives are important. In contrast, in volumetric implicit modelling the interior of the object is also significant, which requires different and more suitable techniques for combining implicit primitives. In this paper, we first discuss irregularities that occur using the current techniques. Then, a new technique for blending implicit primitives, especially appropriate in volumetric modelling (e.g., cloud modelling), is introduced. It overcomes these abnormalities and gives us better results than current techniques.

Odvoj ploskev je bistvenega pomena za nacrtovanje ravninskih vzorcev, potrebnih za izdelavo npr.: letalskih kril, ladijskih trupov, delov avtomobilske plocevine, zgornjih delov cevljev in oblacil. Ceprav lahko za gradnjo sodobnih ladijskih trupov uporabljamo tudi kompozitne materiale, pa ostaja jeklo v ladjedelnistvu se vedno najpogosteje uporabljan material. Zaradi tega ima postopek nacrtovanja ravninskih vzorcev se vedno pomembno vlogo pri konstrukciji ladij. Odvoj vecjega dela ladijskega trupa je dokaj preprost, izjema sta le premec in krma, ki ju odlikuje zahtevna oblika, zaradi cesar potrebujemo ucinkovit algoritem za odvoj ploskev. V tem prispevku je predstavljen novi hitri algoritem za rekonstrukcijo in odvoj ploskev, ki temelji na strategiji deli in vladaj. Za rekonstrukcijo ploskve se uporabljajo odvojni trakovi. Na ta nacin se lahko ploskev odvije v ravnino brez deformacij.

The flattening of digitized surfaces is still very important in design of thin walled objects such as the airplane wings, parts of car bodies, textile products, and shoe uppers. Especially in shoe industry, the ability of quick respond to changing market needs is essential for successful competition. To give needed flexibility to a shoe designer, special CAD/CAM systems have been developed. Those systems are based on algorithms for surface reconstruction and surface flattening. In this article a fast algorithm for surface reconstruction and surface flattening is presented. Developable stripes are used to approximate a surface. In this way the surface can be flattened fast and without any distortions.

The problem of surface flattening is an important one in pattern engineering. Surface flattening is needed for the design of thin-walled objects, such as airplanes' wings, outer ship hulls, parts of car bodies, shoe uppers, and textile products. Although composite materials can be used for building modern ships' hulls, steel is still the most commonly used material for the ship-building industry. Therefore, the pattern engineering process still has an important role in ship designing. For most of the ship hull the flattening is quite simple; the problem is the flattening of the stem and the stern, because the surfaces of these parts of the ship are very complex, and therefore an efficient surface-flattening algorithm is needed. In this article a new fast algorithm for surface reconstruction and surface flattening, based on a divide-and-conquer strategy, is presented. Developable stripes are used to approximate the surface, and in this way the surface can be flattened quickly and without any distortion. (C) 2003 Journal of Mechanical Engineering. All rights reserved.

The problem of surface flattening is an old and widespread problem. It can be found in cartography and in various industry branches. In cartography, this problem is already solved by various projections. In the industry, however, it is still present. In the article, some existent methods and the problems connected with them are given. We also present the new method based on generation of developable stripes, which can be unrolled without any distortion into the plane. In this way, the problem of overlapping of some parts of resulting flat pattern is eliminated. The overlapping problem is especially hard on the doubly curved surfaces. We show that this problem is successfully solved.

Realistic modeling and animating clouds are ones of the hardest tasks in computer animation. There are different techniques used in computer graphics for representing clouds. Our work is based on volume-rendered implicit junction, for volumetric cloud modeling. Basically, implicit primitives are controlled by a modified particle system. We propose genetic algorithms for initialization of the particle system. They provide an alternative to traditional optimization techniques and are also useful in the key-frame animation. Additionally, we introduce some new ideas in volumetric clouds animation: advanced techniques for controlling a large collection of individual elements - flocks and autonomous behavior. Some properties of these techniques are also applicable in the cloud animation.

This paper discusses three distinct techniques for animation of procedural textures and describes the assisting software tool. Animation is attained by moving the rendered point before texture evaluation, changing the definition of texture space or changing the texture colour mapping. Examples are given for textures that base on noise and turbulence functions in order to simulate natural phenomena. Some phases of texture animation process can be automated by using the code generator supported by a library of animation effects. Aspects of practical implementation are discussed and Renderman compliant code is presented.

In this paper, a new fast three-phase method for object reconstruction from 3D scattered points is presented. The first phase is founded on a novel fast triangulation algorithm, which generates a base approximation of the object surface. By inserting bridges, the triangulation algorithm also handles surfaces with genus greater than zero and determines the genus of the reconstructed surface. From results of the first phase, the object surface features, such as sharp edges, silhouette polylines, and corners, are extracted in the next phase. Sharp edges and corners are used as constraints for triangular mesh fairing later in the final phase, where a new improved decimation and a novel mesh refinement procedure are introduced, while silhouette polylines can be applied for generation of a wire-frame model of the reconstructed object. The overall object reconstruction procedure has a tested linear time complexity.