Road Network Analysis with GIS and GRASS-GIS: A Probabilistic Approach

In this paper we show how it can be useful to the probability of intersections in the determination of a classification rule for raster conversions in Geographical Information System (GIS) and GRASS GIS for the Road Network Analysis (RNA). We use a geometric probabilities approach for irregular path considering these results for transportation planning operations. We study two particular problems with irregular tessellations, in order to have a situation more realistic respect to map GIS and considering also the maximum value of probability to narrow the range of possible probability values.

Dataset compilation by GRASS GIS for thematic mapping of Antarctica: Topographic surface, ice thickness, subglacial bed elevation and sediment thickness

This paper presents the GRASS GIS-based thematic mapping of Antarctica using scripting approach and associated datasets on topography and geophysics. The state-of-the art in cartographic development points at two important aspects. The first one comprises shell scripting promoted repeatability of the GIS technique, increased automatization in cartographic workflow, and compatibility of GRASS with Python, PROJ and GDAL libraries which enables advanced geospatial data processing: converting formats, re-projecting and spatial analysis. The second aspect is that data visualization greatly influences geologic research through improving the interpretation between the Antarctic glaciation and surface. This includes the machine learning algorithms of image classification enabling to distinguish between glacier and non-glacier surfaces through automatically partitioning data and analysis of various types of surfaces. Presented detailed maps of Antarctic include visualized datasets from the ETOPO1, GlobSed, EGM96 and Bedmap2 projects. The grids include bed and surface elevation, ETOPO1-based bathymetry and topography, bed, ice and sediment thickness, grounded bed uncertainty, subglacial bed elevation, geoid undulations, ice mask grounded and shelves. Data show the distribution of the present-day glacier, geophysical fields and topographic landforms for analysis of processes and correlations between the geophysical and geological phenomena. Advances in scripting cartography are significant contributions to the geological and glaciological research. Processing high-resolution datasets of Southern Ocean retrieved by remote sensing methods present new steps in automatization of the digital mapping, as presented in this research, and promotes comprehensive monitoring of geological, permafrost and glacial processes in Antarctica. All maps have been plotted using GRASS GIS version 7.8. with technical details of scripts described and interpreted.

A TOOL FOR MACHINE LEARNING BASED DASYMETRIC MAPPING APPROACHES IN GRASS GIS

Socio-economic and demographic data is often released at the level of census administrative units. However, there is often a need for data available at a higher spatial resolution. Dasymetric mapping is an approach that can be used to disaggregate such data into finer levels of detail. It relies on the assumption that proxies available at a higher spatial resolution, along with knowledge of an area, can be used to produce weights in order to spatially reallocate the data to a finer scale layer. The power and efficiency of machine learning (ML) approaches can be taken advantage of when producing weighted layers for dasymetric mapping. Less advanced users, however, may find these approaches too complex. To encourage a wider uptake of such approaches, easy-to-use tools are necessary. GRASS GIS is a free and open-source GIS software that contains many modules for processing geographic data. The existing GRASS GIS add-on “v.area.weigh” already makes the dasymetric mapping approach more accessible, however users must provide their own weighted layer. This paper presents the development of a GRASS GIS add-on, “r.area.createweight”, which provides a simple and convenient tool to facilitate the implementation of a ML-based approach to produce weighted layers for dasymetric mapping. The tool will be available on the official GRASS GIS add-on repository to encourage a more widespread uptake of these approaches.

GeoLinkage: a GRASS-GIS plugin to integrate surface waters and groundwater in WEAP-MODFLOW models

<p>Water resources management requires specialized computer tools that allow explicit integration of surface and groundwater fluxes, which generally have domains with different spatial discretization. On one hand, a surface hydrological domain, D1, is typically segmented in sub-basins, elevation contour bands or hydrological response units. These elements usually are represented by grids, triangles, or simple irregular polygons. In D1, the elements are connected to each other and incorporated into a drainage network that defines a surface topology, t1. On the other hand, an aquifer domain, D2, is organized in hydrogeological units, which can be represented by geometrical elements such as grids, triangulations, Voronoi or Quadratree diagrams. In D2, a regular connection is typically associated to structured meshes that defines a groundwater topology, t2. We present a new tool called GeoLinkage (v.geolinkage) that creates an ESRI-format linkage shapefile of the new surface-groundwater topology, t<sub>1-2</sub>. This python-based open-source tool has a graphical user interface (GUI) as an add-on for GRASS-GIS, which was constructed using Pygrass and Flopy libraries. It was developed to be used in WEAP-MODFLOV models, but it can also be used with other water resources management models. GeoLinkage allows processing models with reasonable computation times, which facilitates scenario analysis. It calculates the locations of the surface element geometries (nodes and arcs) using the GRASS platform and connects them to each element of a structured mesh in MODFLOW models. GeoLinkage was applied to obtain groundwater levels and coverage of water demand in Azapa Valley, a hyper-arid zone in the desert of Chile, where a grid of 70.305 cells and six fields with detailed geometry were processed in only 12 min.</p>

DETERMINATION OF TRANSPORT ACCESSIBILITY IN THE FORMATION OF TOURIST ROUTES USING QGIS AND GRASS GIS

The creation of modern tourist products contributes to the attractiveness of our country in the market of tourist services. Transport accessibility is an important aspect for creating tourism products. This study considers the algorithm for determining transport accessibility for the projection of tourist travel routes, based on the use of geographic information technologies. Transport accessibility is determined by collecting and filtering data and subsequent creation of isochron maps, which show the time distance when moving a particular mode of transport along the lines of the road network from points of interest. Attractions of Ternopil region were chosen as such points of interest for tourists. The paper uses open OSM data on tourist facilities and the road network. Data preparation was performed using PostgreSQL software. When performing the study, the QGIS program was used, in which data processing was performed. Spatial analysis is performed in the spatial information processing environment GRASS GIS; data processing modules or GRASS GIS plug-ins are used. The proposed algorithm allows forming a database of tourist facilities, transport routes, to define more accurately existing tourist routes, to create new ones. As a test in the course of the study, the route of the tour of Ternopil was designed, in the construction of which an isochron map was used. Spatial analysis helps to better determine the path of the tourist tour and its duration.

Okinawa Trough geophysical and topographic modeling by GDAL utilities and GRASS GIS

This paper presents using GDAL utilities and GRASS GIS for topographic analysis of the raster grids based on GEBCO DEM as NetCDF file at 15 arc-second intervals. The focus study area encompasses the area around Okinawa Trough, Ryukyu trench-arc system, southern Japan, East China Sea and the Philippine Sea, West Pacific Ocean. Several GDAL utilities were applied for data processing: gdaldem, gdalwarp, gdalinfo, gdal_translate. The data were imported to GRASS GIS via r.in.gdal. Data visualization highlighted high resolution and accuracy of GEBCO grid, enabling topographic modelling at the advanced level. The algorithm of DEM processing, implemented in GDAL utility gdaldem, was used for generating multi-purpose topographic models: aspect, hillshade, roughness and topographic indices, such as Topographic Position Index (TPI), Terrain Ruggedness Index (TRI). Thematic maps (topography, geoid, marine free-air gravity) were visualized using GRASS GIS modules for raster (d.rast, r.colors, r.contour) and vector (d.vect, v.in.region, d.legend) data processing. The results demonstrated smoother bathymetry in the East China Sea and rugged relief in the Philippine Sea which corresponds to their different geological and geophysical settings. The presented methodology of the topographic analysis based on DEM demonstrated technical aspects of GDAL and GRASS as scripting approach of advanced cartography.

Aplicação de filtros passa-baixa em modelos digitais de elevação para avaliação da diferença altimétrica entre os Pantanais do Negro e Nhecolândia

Os dados do radar interferométrico de abertura sintética SRTM apresentam grande potencialidade para estudos que envolvam a altimetria, uma vez que, além de estarem disponíveis gratuitamente na internet, também estão geocodificados, facilitando seu tratamento em Sistema de informações geográficas. Entretanto os dados SRTM apresentam algumas limitações de uso, entre elas o Efeito Dossel, consequência do modelo considerar o topo da vegetação como feição de relevo. Outra limitação, não menos importante, especialmente para a utilização desses dados em áreas planas, refere-se à precisão vertical desses dados, já que na área deste estudo, situada no Pantanal, uma diferença de apenas um metro tem um significado importante. O presente trabalho possui os objetivos de avaliar os dados de altimetria oriundos dos dados de SRTM, TOPODATA e do GLS; analisar a acurácia vertical, através da comparação dos dados destes sensores com os dados de altitude dos marcos geodésicos do Instituto Brasileiro de Geografia e Estatística; e aplicar Filtro Passa-Baixa de Média Móvel para a correção do "Efeito Dossel" dos dados SRTM. A área de estudo escolhida para realizar todas essas análises está englobada entre os Pantanais do Negro e Nhecolância. A metodologia aplicada foi desenvolvida em ambiente SIG de plataformas gratuitas: GRASS-GIS, Quantum GIS e SPRING. Os dados SRTM utilizados permitiram avaliar a diferença altimétrica entre o Pantanal do Negro e a Nhecolândia. Já os filtros aplicados sobre os dados SRTM diminuíram substancialmente as principais feições associadas ao efeito dossel da vegetação.

O cenário do trabalho do policial militar: espacialização e reflexos no adoecimento funcional

O presente artigo teve como objetivo caracterizar o cenário do trabalho, especificamente, a realidade vivenciada pelo policial militar, bem como as causas desse desempenho sobre o adoecimento funcional, examinando a espacialização das situações de mortes ocorridas no Brasil. Metodologicamente, foi feito uso da pesquisa bibliográfica e censitária, sendo os dados analisados pelo Software Grass gis 7.6.1, mostrados no formato de mapas. Resultados evidenciaram que o realidade de trabalho vivenciada pelo policial militar, em um ambiente de riscos, inseguranças e pressões, interfere em sua vida pessoal, com possibilidades de adoecimento e, inclusive, mortes, como reportadas pelos dados empíricos. Tal cenário demonstra a necessidade de políticas e programas voltados para essa classe profissional, como uma estratégia de mitigação dessas situações marcadas pela insatisfação, estresse, fragilidades e perdas.

Photogrammetric Measurement of Erosion at the Sabbath Point Beothuk Site in Central Newfoundland, Canada

Erosion at archaeological sites in Central Newfoundland, Canada is a major concern, which is compounded by the fact that there has been a dearth of archaeological research in this region. While more than 70 house pits are known, very few excavations have examined whole features in the Exploits River Valley (ERV), and the archaeology of many has not been examined yet. The aim of this study is to examine the rate of erosion at the Sabbath Point house pit, a recently recorded archaeological site, located on the bank of Red Indian Lake (RIL), and to describe a low-cost methodology for analysing site level bank changes. This site is particularly important, as it represents an example of a late Beothuk residential feature about lifeways practiced in this region. The surveys employed here were carried out using image-based modelling. GRASS GIS was used to measure the diachronic difference between bank edges. The Digital Elevation Models (DEMs) were then compared, and the differences were measured using a transect based method. The erosion measurement has shown that Sabbath Point is in danger of being completely eroded. This shows that a salvage excavation program covering the entire feature is necessary within the next few years, as the feature itself will begin to erode.