Polygonal Map Research Articles

Evaluation of the use of very high resolution aerial imagery for accurate ice-wedge polygon mapping (Adventdalen, Svalbard)

The main objective of this paper is to verify the accuracy of delineating and characterizing ice-wedge polygonal networks with features exclusively extracted from remotely sensed images of very high resolution. This kind of mapping plays a key role for quantifying ice-wedge degradation in warming permafrost. The evaluation of mapping a network is performed in this study with two sets of aerial images that are compared to ground reference data determined by fieldwork on the same network, located in Adventdalen, Svalbard (78°N). One aerial dataset is obtained from a photogrammetric survey with RGB+NIR imagery of 20cm/pixel, the other from an UAV (Unmanned Aerial Vehicle) survey that acquired RGB images of 6cm/pixel of spatial resolution. Besides evaluating the degree of matching between the delineations, the morphometric and topological features computed for the differently mapped versions of the network are also confronted, to have a more solid basis of comparison. The results obtained are similar enough to admit that remotely sensed images of very high resolution are an adequate support to provide extensive characterizations and classifications of this kind of patterned ground.

The third dimension of political mapping: exploiting map interactivity for a better understanding of election and referendum results

Density-equalizing cartograms in the Euclidian plane are the usual cartographic solution for the discrepancy between the topographic nature of the GIS map, reflecting the extent of land surfaces, and the demographic nature of a vote, pertaining to the number of voters expressing a given political choice. Cartograms adapt map polygon areas to population sizes. Contemporary mapping technologies allow a different approach by giving access to interactive models in which the third dimension of space can be used to reflect a demographic variable while leaving the topographic base-map intact. This offers an answer to concerns about cartogram readability by the general public. Examples from Austrian election and Swiss referendum results are given to illustrate our approach.

Natura 2000 protected habitats, Massaciuccoli Lake (northern Tuscany, Italy)

ABSTRACTThe Massaciuccoli Lake (northern Tuscany, Italy) Natura 2000 habitat map (1:10,000) was compiled from photo-interpretation and recent phytosociological studies, integrated by field surveys of the vegetation units. Conventional geographical information system procedures were used to select and manage spatial information. The following attributes were assigned to each map polygon: (i) vegetation type, (ii) habitat typology and (iii) percentage cover of the habitat type. Habitat types covering polygons smaller than 50 m2 were treated as points. A total of nine Natura 2000 habitat types were identified and mapped; they cover almost 20% of the study area. The results show that of all sites on the Italian peninsula, Lake Massaciuccoli Calcareous fens with Cladium mariscus covers the largest surface area and is crucial for the national conservation of this habitat type. It is also of priority importance in Europe.

The third dimension of political mapping: exploiting map interactivity for a better understanding of election and referendum results

ABSTRACTDensity-equalizing cartograms in the Euclidian plane are the usual cartographic solution for the discrepancy between the topographic nature of the GIS map, reflecting the extent of land surfaces, and the demographic nature of a vote, pertaining to the number of voters expressing a given political choice. Cartograms adapt map polygon areas to population sizes. Contemporary mapping technologies allow a different approach by giving access to interactive models in which the third dimension of space can be used to reflect a demographic variable while leaving the topographic base-map intact. This offers an answer to concerns about cartogram readability by the general public. Examples from Austrian election and Swiss referendum results are given to illustrate our approach.

Gully erosion regionalization of black soil area in northeastern China

Gully erosion is the frequent and main form of soil erosion in the black soil area of the northeastern China, which is one of the most important commodity grain production bases in China. It is encroaching upon the fertile farmland there. Regionalization of gully erosion can reveal the spatial distribution and regularity of the development of gully erosion. Based on the eco-geographical regional background features of the black soil area, this study combined the regionalization with influencing factors of the development of gully erosion. GIS spatial analysis, geostatistical analysis, spatial statistics, reclassification, debris polygon processing and map algebra methods were employed. As a result, the black soil area was divided into 12 subregions. The field survey data on type, length, volume and other characteristics indicators of gully erosion were used to calibrate the results. Then the features of every subregion, such as where the gully erosion is, how serious it is, and why it happens and develops, were expounded. The result is not only an essential prerequisite for gully erosion surveys and monitoring, but also an important basis for gully erosion prevention.

Mixed methods participatory GIS: An evaluation of the validity of qualitative and quantitative mapping methods

Participatory mapping in social research is characterized by methodological pluralism, with two common methods being qualitative mapping using stakeholder interviews and quantitative methods that engage larger public samples through digital, internet mapping. To date, there has been no systematic evaluation of the extent to which mixed methods in participatory mapping yield valid results when applied to the same research setting and research questions. A mixed methods research design (combined exploratory sequential and convergent parallel) was implemented in a large research project to identify marine and coastal values in the Kimberley region of Australia. Qualitative interviews (n = 167) were completed with stakeholders to identify place-based values using polygon mapping methods and internet-based public participation GIS (PPGIS) methods (n = 578). We defined and operationalized the concepts of concurrent, commensurate, and convergent validity to assess mixed methods research outcomes. We found that qualitative and quantitative methods resulted in moderate to high concurrent validity when assessing the importance of place values in the study area. Convergent validity (spatial) was highly variable by place value, with stronger convergent validity found with mapped aesthetic, recreational fishing, tourism, biodiversity, and Aboriginal culture values, and weakest with existence, therapeutic, and commercial fishing values. Convergent validity was influenced by weak commensurate validity through the use of different geometric features (polygons versus points) for mapping values across a large study area. The utility of mixed methods for planning decision support in a convergent parallel design depends on demonstrating convergence in construct meaning, spatial location, and consistency in values in the sampling populations.

A new watermarking method for vector map data

In this paper, we propose a new digital watermarking method for protecting of vector data in geographic information systems. The method is based on a combination of two novel approaches. Firstly, the watermark information is embedded into the polygon map objects by cyclically shifting the list of vertices of each polygon. Secondly, instead of a bit vector, a raster image superimposed on the map is considered as a watermark. The major advantage of this method is that it does not distort the map by altering the coordinate values. A simple example demonstrates the method efficiency, as well as the robustness of the embedded watermark against geometric transformations usually performed when working with map data: translation, scaling, rotation and cropping.

Composition and spatial structure of dwarf shrub heath in Norway

ABSTRACTDetailed descriptions of individual vegetation types shown on vegetation maps can improve the ways in which the composition and spatial structure within the types are understood. The authors therefore examined dwarf shrub heath, a vegetation type covering large areas and found in many parts of the Norwegian mountains. They used data from point samples obtained in a wall-to-wall area frame survey. The point sampling method provided data that gave a good understanding of the composition and structure of the vegetation type, but also revealed a difference between variation within the vegetation type itself (intra-class variation) and variation resulting from the inclusion of other types of vegetation inside the map polygons (landscape variation). Intra-class variation reflected differences in the botanical composition of the vegetation type itself, whereas landscape variation represented differences in the land-cover composition of the broader landscape in which the vegetation type was found. Both types of variation were related to environmental gradients. The authors conclude that integrated point sampling method is an efficient way to achieve increased understanding of the content of a vegetation map and can be implemented as a supporting activity during a survey.

POLYGONAL QUASICONFORMAL MAPPINGS AND CHORD-ARC CURVES

In this paper we show that a polygonal quasiconformal mapping always corresponds to a chord-arc curve. Furthermore, we find that the set of curves corresponding to polygonal quasiconformal mappings is path connected in the set of all bounded chord-arc curves.

키넥트 거리센서를 이용한 실내 이동로봇의 위치인식 및 3 차원 다각평면 지도 작성

키넥트 거리센서를 이용한 실내 이동로봇의 위치인식 및 3 차원 다각평면 지도 작성

Spatio-Temporal Pattern of Breast Cancer - Case Study of Southern Karnataka, India.

Spatio-ecological study of disease provides a framework to study the interaction of genetic, environmental, social, cultural and behavioural factors on people's health. The occurrence and interaction of these factors are different in different places, giving rise to distinct geographic or spatial variation. Diseases like breast cancer have variation both spatially and temporally. Public health practitioners can use Geographic Information System (GIS) as a visualization tool to effectively present geographic phenomenon and depict it in maps that might remain otherwise undiscovered in tabular form. To demonstrate how GIS can be used to understand and communicate breast cancer data through spatial visualization techniques. (i) To visualize the Spatial Distribution of Breast cancer incidences by a point map. (ii) To visualize the Temporal distribution of breast cancer incidences by thematic maps for the study period of 2007 -2011. Total 1090 breast cancer case records collected for the year 2007-2012 were segregated taluk wise for the 29 taluks and geocoded using the address of the patient, creating a point map. ArcGIS 10.2 software was used to prepare thematic map of breast cancer cases. The taluk wise aggregated breast cancer incidence from the year 2007 to 2011 was then attributed into polygon map representing taluks (Base Map). Natural break data classification technique was used to classify the breast cancer incidence data and breast cancer incidences were classified as low, moderate, high and very high. Spatial distribution of breast cancer incidences using thematic mapping methods high incidences were reported in MY_ T24 (Hunsur), MY_ T25 (KR Nagar), MY_27 (Nanjangud), CH_T1 (Chamrajnagar) and CH-T2 (Gundlupet). Temporal maps prepared for the study from 2007 to 2011 showed that Mysore Taluk had very high Incidence level and the same was observed throughout the study period. The taluks which have high and moderate intensities seem to be fluctuating. However, 25 taluks do not fall into very high category during the study period. Taluks such Gundlupet (CH_T2), K R Nagar (MY_T25), Kollegal (CH_T3) have been observed to enter high intensity category during the year 2011 from moderate intensity. It is also observed that Nanjangud (MY_T27) is in high intensity category throughout the study period which might be due to its proximity to Mysore urban. Analysis of Breast Cancer in southern Karnataka using GIS has revealed that urban areas of Mysore has the highest risk of breast cancer and the temporal trends reveal that even rural areas with moderate risk are moving towards high risk areas.

Effectiveness of visually analyzing LiDAR DTM derivatives for earth and debris slide inventory mapping for statistical susceptibility modeling

Landslide inventories are the most important data source for landslide process, susceptibility, hazard, and risk analyses. The objective of this study was to identify an effective method for mapping a landslide inventory for a large study area (19,186 km2) from Light Detection and Ranging (LiDAR) digital terrain model (DTM) derivatives. This inventory should in particular be optimized for statistical susceptibility modeling of earth and debris slides. We compared the mapping of a representative set of landslide bodies with polygons (earth and debris slides, earth flows, complex landslides, and areas with slides) and a substantially complete set of earth and debris slide main scarps with points by visual interpretation of LiDAR DTM derivatives. The effectiveness of the two mapping methods was estimated by evaluating the requirements on an inventory used for statistical susceptibility modeling and their fulfillment by our mapped inventories. The resulting landslide inventories improved the knowledge on landslide events in the study area and outlined the heterogeneity of the study area with respect to landslide susceptibility. The obtained effectiveness estimate demonstrated that none of our mapped inventories are perfect for statistical landslide susceptibility modeling. However, opposed to mapping polygons, mapping earth and debris slides with a point in the main scarp were most effective for statistical susceptibility modeling within large study areas. Therefore, earth and debris slides were mapped with points in the main scarp in entire Lower Austria. The advantages, drawbacks, and effectiveness of landslide mapping on the basis of LiDAR DTM derivatives compared to other imagery and techniques were discussed.

Quantitative Measures for Cartogram Generation Techniques

AbstractCartograms are used to visualize geographically distributed data by scaling the regions of a map (e.g., US states) such that their areas are proportional to some data associated with them (e.g., population). Thus the cartogram computation problem can be considered as a map deformation problem where the input is a planar polygonal map M and an assignment of some positive weight for each region. The goal is to create a deformed map M′, where the area of each region realizes the weight assigned to it (no cartographic error) while the overall map remains readable and recognizable (e.g., the topology, relative positions and shapes of the regions remain as close to those before the deformation as possible). Although several such measures of cartogram quality are well‐known, different cartogram generation methods optimize different features and there is no standard set of quantitative metrics. In this paper we define such a set of seven quantitative measures, designed to evaluate how faithfully a cartogram represents the desired weights and to estimate the readability of the final representation. We then study several cartogram‐generation algorithms and compare them in terms of these quantitative measures.

Detailed Natura 2000 and CORINE Biotopes habitat maps of the island of Elba (Tuscan Archipelago, Italy)

The island of Elba (Tuscan Archipelago, Italy) Natura 2000 habitat map (1:25,000) and the CORINE Biotopes habitat map (1:25,000) were derived from the phytosociological map of Elba integrated with recent studies and field knowledge of the vegetation units. Conventional geographical information system queries were used to manage and select the spatial information. For each map polygon, the following attributes were assigned: (i) habitat typology and (ii) percentage cover of each habitat type. Where multiple habitat types were associated with the same polygon, the percentage cover of each habitat type was estimated. A total of 27 Natura 2000 habitat types and 58 CORINE Biotopes habitat types were identified, these being distributed in single and/or multiple typological units. Distribution and covers of the different habitat types are discussed. The usefulness of this kind of map for monitoring and managing conservation actions is discussed.

Method development to extract spatial association structure from soil polygon maps

Existing soil information systems contain mainly qualitative data on soilscapes, however, quantitative data would be necessary to more eff ectively guide digital soil mapping eff orts. Detailed analysis of small scale overview maps off ers the most appropriate way to delineate soilscapes where they are available. In our study, the genetic soil map of Hungary have been used which displays the most complete representation of the Hungarian Soil Classifi cation System. Our goal was to analyse spatial association structure based on the boundary segments between soil polygons. We transformed the polygons into lines. The features of each line segment were the names (or codes) of the soil polygons on both sides. Aft er omission soils with low representation (less than three polygons) and boundaries beside state border, forests and cities, 69 soil units were retained. We calculated a similarity matrix among soil types based on logarithm of ratios between existing segment lengths and theoretical segment lengths. The theoretical lengths were calculated with a Chi-squared calculation by using sums of lengths in rows and columns in the 69 × 69 matrix. The similarity matrix was converted into dissimilarity matrix to distinguish between complete dissimilarity (missing values) and complete similarity (main diagonal). Dissimilarity matrix was clustered and represented in a form of dendrogram both in original form and aft er dimension reduction with multidimensional scaling method. Our method has resulted a promising approach for delineating soilscapes in presence of overview soil maps. The study resulted fuzzy soilscapes with broad transition zones. The method could be refi ned by using variable sized moving window method and by combining boundary data with terrain, geology etc.

A Pedological Tale IV: Conversations with Turtle, Bear, and Eagle

A Pedological Tale IV: Conversations with Turtle, Bear, and Eagle

The transformation of cuts in the conformational mapping of circular polygons in problems of liquid and gas mechanics

A linear differential equation of the Fuchs class with six regular singular points is considered, which corresponds to the problem of the conformal mapping of circular hexagons in polar nets with two cuts that are characteristic in the theory of jets and cavitation, the theory of gliding, in gas dynamics, in the theory of the motion of ground waters and in seepage theory. It is shown that, in the case of a fixed parameter, characterizing the ratio of the radii of the circular ares constituting the opposite sides of a polygon on which there are cuts, the configuration and mutual arrangement of the cuts depend considerably not so much on the known properties of theta-functions, on the basis of which special solutions of the equation considered are constructed, but on the ranges of variation in the constants of the conformal mapping occurring in the expression for the mapping functions as well as the modulus of the elliptic functions. It is found that cuts that are different in their configuration and mutual arrangement can correspond to different ranges of variation in these constants in the corresponding region of the velocity hodograph which is evidence of the transformation of the fluid seepage flows depending on the effect of various physical factors.

Operationalizing digital soil mapping for nationwide updating of the 1:50,000 soil map of the Netherlands

This paper presents a pedometric approach to updating the Dutch 1:50,000 national soil map for the peatlands, and illustrates this approach for a 187,525ha area in the northern peatlands. This is the first time that digital soil mapping replaces conventional soil mapping in a nationwide, government-funded soil survey program in the Netherlands. Soil classes were updated indirectly through mapping two quantitative diagnostic soil properties: the thickness and starting depth of the peat layer. From these, five major soil groups could be constructed. Because the point data were zero-inflated, a two-step simulation approach was implemented. First, peat presence/absence indicators were simulated from probabilities of peat occurrence that were predicted with a generalized linear model. Second, conditional peat thickness values were simulated from kriging with external drift predictions. The indicator and peat thickness simulations were combined to obtain simulations of the unconditional peat thickness. A similar approach was followed for the starting depth. From the simulated soil properties, probability distributions of soil groups were derived. These groups were refined with information on (static) soil properties derived from the 1:50,000 map to obtain soil classes according to the 1:50,000 legend. The updated raster map was then incorporated in the 1:50,000 polygon map. The prediction models were calibrated with legacy point data, that were updated for peat thickness before being used, in addition to a set of newly acquired point data. The uncertainty associated to the updated peat thickness values in the legacy dataset was quantified and accounted for by the prediction models. The peat thickness map and a map with three soil orders were validated with independent probability sample data. The overall purity of the soil order map was 66% for both subareas. For subarea 1 this was a 12% purity improvement compared to the current 1:50,000 map, for subarea 2 this was 3%. For subarea 1, the mean absolute error of the predicted peat thickness was 23.5cm, and the R2 is 0.50. For subarea 2 these accuracy measures were 30.9cm and 0.65. We conclude that nationwide updating the 1:50,000 map with pedometric techniques is feasible. In order to increase the value and usability of the legacy point data as well as the large set of newly acquired field observations and the updated 1:50,000 map, we recommend installation of a soil monitoring network in the Dutch peatlands.

An Extended Evaluation of Open Source Surface Reconstruction Software for Robotic Applications

With the raising popularity of 3D sensors in robotic applications, e.g., RGB-D cameras or laser scanners, the demand for fast and reliable methods for surface reconstruction from 3D point clouds increases. Currently, several freely available implementations of such algorithms exist. This paper presents an evaluation of the usability of different open source software packages for polygonal map generation in robotic contexts.

Climatic characterization of forest zones across administrative boundaries improves conservation planning

Aim This paper demonstrates methods to extend standardized vegetation zone descriptions and mapped distributions across political boundaries. An extended climate niche for North America's Coastal Douglas-fir (CDF) forest zone is determined and projected to evaluate its potential distribution under a changing climate and to identify climate refugia for conservation planning. Location Pacific Northwest temperate rain forest in British Columbia (BC), CA, and nearby Washington (WA) and Oregon (OR), US. Methods Using a combination of ecosystem polygon mapping and ecological plot data with climate interpolation tools, forests characterized as CDF under BC's biogeoclimatic ecosystem classification system were identified in the neighbouring US. Current (baseline) limits to CDF distribution were identified and used to map its potential distribution and climate refugia under future climate conditions using ensemble Global Climate Model projections. Results The extended CDF climate niche covers 76 725 km2 under baseline conditions, with the majority of the area in the Pacific Northwest US. The extended CDF forest zone includes a vegetation assemblage consistent with existing definitions of BC's CDF moist maritime subzone, but also an additional vegetation assemblage representing a drier maritime subzone. Projections of future climate suggest a northerly shift (~150 km) and a decrease (−91.5%) in overall CDF area. Climate refugia are projected for discontinuous patches of CDF forest on Vancouver Island and adjacent mainland. Conclusions This project combined georeferenced ecological plot data and digital maps, thereby facilitating the international mapping of ecosystem distributions in adjacent administrative areas that do not currently use the same ecosystem classification and mapping systems. This approach and the concept of climate niche definition, distribution and persistence are applicable to the management, restoration and conservation of plant communities, particularly in evaluating future ecosystem range shifts and disruptions associated with a changing climate. The potential for dramatic reductions in the range of the Coastal Douglas-fir zone, with persistence in <15% of its current area, suggest that most of the extended CDF zone is marginally suitable for the characteristic CDF ecosystems and that slight shifts in climate or disturbance regime may greatly alter the character of the vegetation. The full climatic niche for British Columbia's Coastal Douglas-fir forest zone is determined from its mapped distribution and georeferenced plot data in the neighbouring USA. A new subzone is characterized, and the potential distribution of the extended zone is projected under a changing climate to identify climate refugia. For sensitive ecosystems with multi-jurisdictional distributions, this approach helps focus conservation efforts.