Geomatics and Environmental Engineering
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ISSN 1898-1135
e-ISSN: 2300-7095
Issue Date
2010
Volume
Vol. 4
Number
No. 4
Description
Journal Volume
Geomatics and Environmental Engineering
Vol. 4 (2010)
Projects
Pages
Articles
Polyhedral building model from airborne laser scanning data
(2010) Borowiec, Natalia
This paper presents the semi-automatic method, which only uses ALS data to build a model of a building. This method focuses on modeling the roof, assuming that by knowing the shape of the roof and the digital presentation of the terrain, we could easily obtain the model of the whole building. A unique feature of this method is the sequential regular and irregular tesselations, which are used to obtain analyses of grid and tin. This method consists of three main steps. The first step is to execute the interpolation of lidar points to the grid and then indicate the places where buildings are most likely to be present. The region of interest (in this case, the buildings) is located on the grid using the easy grid analyses. The next step helps us to indicate the edge of a building's roof. Accurately detecting the edges is possible when using the original data but we are limited to the ROI indicated in the first step. The lines which define the roof edges were detected as a result of the TIN analysis. The edges of the building allow us to choose only those points which represent the roof out of the entire "cloud of points" and proceed to the next step. The third step consists of planes detection, in which we define the shape of the building's roof. The roof planes are detected using the split-merge method in which a LIDAR point cloud is organized and planes are extracted from each voxel. The planes are joined when parameters such as slope, azimuth and height are contained in the definition of boundary. The final step is exporting the building model to dxf format.
Relationships between microbial and chemical properties in mine soils reclaimed for forestry
(2010) Chodak, Marcin
Measurement of several microbial properties is necessary for comprehensive assessment of mine soils. Therefore, the applied methods should maximize amount of acquired information. Objectives of the work were to assess relationships between microbial properties of mine soils and to assess of their dependence on some soil chemical and physico-chemical properties. The measured microbial properties included microbial biomass, basal respiration, activities of dehydrogenase, acid phosphatase and urease. Biolog® assay was used to assess physiological properties of soil microbial communities. The chemical and physico-chemical properties included the contents of C, N and pH in KCl. Spearman correlation was applied to study relationships between the properties measured. Most of microbial properties were correlated with each other. However, the Biolog® derived parameters weakly correlated with Cmic and enzyme activities what indicates that they bear complementary information on soil microbial communities. Activities of acid phosphatase and urease depended mainly on microbial biomass. Positive correlation between Shannon index based on Biolog® data and microbial biomass indicates that in the mine soil the physiological abilities of microbial communities increase as increases the microbial biomass.
Statistical algorithms for modelling the results of geodetic observations
(2010) Czaja, Józef; Dąbrowski, Janusz
The article presents the principles for linearizing observational equations describing functional relations in the field of geodesy. An algorithm for solving overdetermined systems of equations with a rank deficient coefficient matrix is then formulated. The estimation of parameters which describe the given process is based on the Gauss-Markov model, using the generalized inverse of the normal equations matrix. Variance analysis is used to present formulae for estimating the covariance matrix for the vector of unknowns which is the basis for evaluating the accuracy of the estimated parameters. In the last section, a practical illustration of the proposed algorithm is presented, applied to the modelling of survey observation results in order to estimate the elevation of a water table at four ground points.
Repetitive measurements of the strain state in the rock mass persistently disturbed by the mining exploitation - focus on the triangular rosette
(2010) Ćwiąkała, Paweł; Skulich, Mikołaj; Szafarczyk, Anna
Underground mining exploitation causes many negative effects on the surface of the mining area. Among the biggest nuisances for the buildings, one should count the arising of squeezing and stretching stress, and the description of the arising deformations is an important element of the safety assessment of the objects on the surface. The measurements and calculations, carried out on measurement rosettes, allow defining strains occurring in the ground in any direction. The article presents the results of the measurements with a triangular measurement rosette situated over the exploited deposit during the whole process of the wall exploitation. The theoretical description to define the surface tensor of strains was also given.
Sub-pixel classification of middle-resolution satellite images - evaluation of regression trees applicability to monitor impervious surfaces coverage
(2010) Drzewiecki, Wojciech
The aim of the presented research was to test the method of assessing the imperviousness index on the basis of middle-resolution satellite images with the use of regression trees. The task also included evaluation of the applicability of the method to monitor the changes of impervious surfaces coverage. The research has been done in the catchments of Prądnik and Dłubnia rivers (Malopolska region, Poland). The imperviousness index has been assessed for two time periods - current state (2007) and the mid-1990s. The training and verification data for both time periods have been obtained from aerial orthophotomaps for urban, suburban, rural, industrial and commercial areas. In both time states the best assessment of imperviousness index have been achieved for the variants where the regression trees were built on the basis of all satellite data accessible for the time period. However, it is worth notifying that the variant with the input data limited to three images from spring, summer and autumn provided comparable accuracy of the results. These models have the systematic error between 1.3-2.2%, the mean error between 15.8-16.4% and correlation coefficient between 0.85-0.86 for the mid-1990s. For the year 2009 these values are respectively: 1.4-1.7%, 15.7-16.0% and 0.86. The accuracy of the imperviousness index obtained in the present research is comparable with the accuracy obtained with the use of regression trees in research reported in the literature. The comparison has shown high accuracy of imperviousness index change assessment for the whole population of pixels in verification dataset. The systematic error is 0.1%. However, the obtained assessment accuracy for a single pixel (±14.5%) can be too low for some applications.