Pavol Federl

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We introduce a class of biologically-motivated algorithms for generating leaf venation patterns. These algorithms simulate the interplay between three processes: (1) development of veins towards hormone (auxin) sources embedded in the leaf blade; (2) modification of the hormone source distribution by the proximity of veins; and (3) modification of both the(More)
Because of their complexity, plant models used in computer graphics are commonly created with procedural methods. A difficult problem is the user control of these models: a small number of parameters is insufficient to specify plant characteristics in detail, while large numbers of parameters are tedious to manipulate and difficult to comprehend. To address(More)
We present a model of fracture formation on surfaces of bilayered materials. The model makes it possible to synthesize patterns of fractures induced by growth or shrinkage of one layer with respect to another. We use the finite element method (FEM) to obtain numerical solutions. This paper improves the standard FEM with techniques needed to efficiently(More)
In this paper we present a model of fracture formation on surfaces of bi-layered materials. The model allows synthesis of realistic patterns occurring in nature as a result of cracking induced by growth or shrinkage of one layer with respect to another. Two different discretizations of the problem are discussed. First we revisit an existing mass-spring(More)
Many activities in computer graphics can be regarded as experiments on virtual objects or models. In the process of experimentation the existing models are gradually improved and new model categories emerge. The Virtual Laboratory (vlab) is a software environment designed to support model development by facilitating the manipulation of models and providing(More)
Mathematical modeling of growing multicellular structures creates the problem of solving systems of equations in which not only the values of variables, but the equations themselves, may change over time. We consider this problem in the framework of Lindenmayer systems, a standard formalism for modeling plants, and show how parametric context−sensitive(More)
This paper introduces a method for creating naturally varied plants from a given basic plant model. Previous techniques create variation in plants by introducing local randomness to the plant model’s description. However, randomness is restricted by the model’s parameterization and lack of correlation between local features making varying global properties(More)
Here we describe a project that deals with license plate location in raster images. The algorithm takes a raster image as input, and yields the position of a plate in the image. After the position is determined, the algorithm can determine the locations of the license plate characters, which could be easily combined with an OCR algorithm to convert the(More)
Several hypotheses have been formed to explain vein pattern formation. Sachs proposed that veins develop as a result of the gradual canalisation of auxin: the auxin transport capacity of some cell files increases, draining auxin from neighbouring cell files. Mitchison implemented models of auxin canalisation by postulating that the transport of auxin(More)