6,245 research outputs found
A Quantitative Comparison of Completely Visible Cadastral Parcels Using Satellite Images:A Step towards Automation
Estimates suggest that 70 percent of the world’s population has little or no access to formal land administration systems and hence their rights are often neither recognized nor secured by governments. A system of organized land rights information, embedded in a broader land administration system, is argued as a key pillar for underpinning any sustainable economy and equitable economic development. Cadastres are a core ingredient of any land administration system. Traditional methods for cadastral surveying and mapping are however, often lengthy and labor intensive. In response, remote sensing based techniques have great potential and are being increasingly employed for rapid creation and upgrading of cadastral maps: the Global Land Tool Network (GLTN)’s fit-for-purpose (FFP) land administration guidelines provide ample evidence in this regard. Furthermore, (semi)-automatic methods for detecting cadastral boundaries are currently under development. These methods seek to make use of very high resolution (VHR) satellite images or sensors capable of similar resolutions. Creating approaches that are both highly automated and transferable between contexts remain a challenge owing to diverse morphologies of parcel boundaries found across contexts. Anyhow, object-based image analysis methods appear highly promising as they mimic the human interpretation process to identify features from an image. A pre-step to utilizing any of these methods should be determining the quantity of the boundaries that are actually identifiable through visual interpretation. Therefore, in this paper, we assess the quantity of visible/non-visible boundaries in different contexts with the aim of determining the percentage of known cadastral parcels that are completely visible via VHR satellite images. For this purpose, we selected subsets from case locations in the contexts of Ethiopia, Ghana, Kenya, Mozambique, Rwanda, Guatemala and Nepal. To cover different landscapes, a combination of rural, peri-urban and urban areas were included. In each case, control cadastral data (i.e. vector files or existing cadastral maps) served as a reference for the assessment. Results show significant difference between visual identification for the samples from seven contexts. The percentage of completely visible cadastral parcels ranged from zero to 71 percent when compared to the reference cadastral map. These were parcels for which all boundaries were fully visible, i.e. a closed polygon. Considering the result of the study, it appears that (semi)-automated cadastral boundary extraction methods using VHR imagery will have high utility in specific contexts (e.g. smallholder and rural), whereas their use in complex urban environments may be challenging and require other methods or data. Nonetheless, an approach like this will greatly enhance the application of FFP approach in Land Administration for cadastral mapping in areas where no relaible data exists, for e.g. even if a small amount of boundaries could be automatically generated (e.g. 30 percent), potentially large cost reductions in cadastral surveying and mapping could be achieved
Structural analyses of features in cultural landscapes based on historical cadastral maps and GIS
A landscape may appear to be ancient and to contain old man-made structures even if this is not the whole truth. Structures are moved, removed, replaced and added over the years. New users introduce new land use and management regimes. In Norway, information from land consolidation processes is crucially important in gaining a better understanding of the history, dynamics and development of farms, identifying older traces of human activity and selecting important areas for protection and management. When cadastral maps are transformed, common points are needed during the transformation process and for testing the accuracy of the final transformation. It is often difficult to find enough common points to satisfy statistical requirements. Paper I presents a simple method using buffers based on linear features to evaluate whether or not the accuracy of the transformation results is better than the known accuracy of the source. Papers II, III and IV show how digitised and geographically referenced historical cadastral maps can be used to reconstruct the situation at various dates back to the 19th century, and for some information back to the 16th century. The digitised cadastral map provides a snapshot of the situation at the time of the land consolidation process, and the information is considered to be very exact. Paper IV also demonstrates how a DEM (digital elevation model) can add significantly to an understanding of the information contained in the land consolidation material. The use of digitised cadastral maps reveals that many man-made structures generally perceived as old, because they are constructed using traditional techniques, in fact date from after the land consolidation process. One aim of the new European Landscape Convention is to promote landscape protection, management and planning. It therefore requires identification of landscapes and analysis of their characteristics and the forces and pressures transforming them. Using land consolidation material in a GIS makes it possible to document changes in a landscape and improve understanding of the pressures behind these changes
The fourth dimension in landscape analysis: changing of heritage and ecological values in the Évora cultural landscapes.
Time is one of the most important driving forces in Landscape Ecology. Time along with geosystem, biosystem and socialsystem determines landscape heterogeneity which reveals itself in different patterns and functions. Cultural Landscapes are the result of the interactions between man and environment along time
Height of successional vegetation indicates moment of agricultural land abandonment
One of the major land use and land cover changes in Europe is agricultural land abandonment (ALA) that particularly affects marginal mountain areas. Accurate mapping of ALA patterns and timing is important for understanding its determinants and the environmental and socio-economic consequences. In highly fragmented agricultural landscapes with small-scale farming, subtle land use changes following ALA can be detected with high resolution remotely sensed data, and successional vegetation height is a possible indicator of ALA timing. The main aim of this study was to determine the relationship between successional vegetation height and the timing of agricultural land abandonment in the Budzów community in the Polish Carpathians. Areas of vegetation succession were vectorized on 1977, 1997, and 2009 orthophotomaps, enabling the distinguishing of vegetation encroaching on abandoned fields before and after 1997. Vegetation height in 2012-2014 was determined from digital surface and terrain models that were derived from airborne laser scanning data. The median heights of successional vegetation that started development before and after 1997 were different (6.9 m and 3.2 m, respectively). No significant correlations between successional vegetation height and elevation, slope, aspect, and proximity to forest were found. Thus, the timing of agricultural land abandonment is the most important factor influencing vegetation height, whereas environmental characteristics on this scale of investigation may be neglected
Multi-hazard risk assessment using GIS in urban areas: a case study for the city of Turrialba, Costa Rica
In the framework of the UNESCO sponsored project on “Capacity Building for Natural Disaster Reduction” a case study was carried out on multi-hazard risk assessment of the city of Turrialba, located in the central part of Costa Rica. The city with a population of 33,000 people is located in an area, which is regularly affected by flooding, landslides and earthquakes. In order to assist the local emergency commission and the municipality, a pilot study was carried out in the development of a GIS –based system for risk assessment and management. The work was made using an orthophoto as basis, on which all buildings, land parcels and roads, within the city and its direct surroundings were digitized, resulting in a digital parcel map, for which a number of hazard and vulnerability attributes were collected in the field. Based on historical information a GIS database was generated, which was used to generate flood depth maps for different return periods. For determining the seismic hazard a modified version of the Radius approach was used and the landslide hazard was determined based on the historical landslide inventory and a number of factor maps, using a statistical approach. The cadastral database of the city was used, in combination with the various hazard maps for different return periods to generate vulnerability maps for the city. In order to determine cost of the elements at risk, differentiation was made between the costs of the constructions and the costs of the contents of the buildings. The cost maps were combined with the vulnerability maps and the hazard maps per hazard type for the different return periods, in order to obtain graphs of probability versus potential damage. The resulting database can be a tool for local authorities to determine the effect of certain mitigation measures, for which a cost-benefit analysis can be carried out. The database also serves as an important tool in the disaster preparedness phase of disaster management at the municipal level
Maps, fields, and boundary cairns: demarcation and resistance in colonial Cyprus
An important component of the administration and control of a colony by an external power was the demarcation and classification of the land and its people. This was certainly the case in Cyprus under British colonial rule (1878-1960), as three case studies demonstrate: the topographical survey of the island by H. H. Kitchener in 1878-1883; the cadastral survey of 1909-1929; and the work of the forest delimitation commission from 1881 to 1896. This was not achieved without resistance on a variety of levels. Ironically, part of the opposition came from the structure of the colonial demarcation and classification project itself
Land Use Changes and Their Perception in the Hinterland of Barranquilla, Colombian Caribbean
The coastal strip of the western peri-urban area of Barranquilla in the Atlántico Department (Colombia) is experiencing changes in human-environment interactions through infrastructure, residential, and tourism projects in a vulnerable landscape. In the hilly area, fragments of biodiverse tropical dry forest still exist in various states of conservation and degradation. To understand the interrelated social, economic, and ecological transformations in the area, we analyzed land use change on the local scale including the local community’s perception, because the local community is a key actor for sustainable land use. For the analysis of the interrelated social, economic, and ecological processes, we combined visual interpretation of high-resolution satellite imagery, on-site field land use mapping, and a spatial statistical analysis of the distribution of land use classes with in-depth interviews and a participatory GIS workshop, thus benefitting from the complementary methodological strengths of these approaches. The case study is the rural community of El Morro, which exhibits the typical social, economic, and ecological changes of the coastal strip of the western peri-urban area of Barranquilla. The local community perceives a continuous loss of forest area, but observations from on-site field mapping cannot confirm this linear trend. We observed a gradual replacement of traditional land uses such as smallholder agriculture, charcoal production, and cattle breeding by services for tourism, gated community projects for urban dwellers, and infrastructure projects; these spatial developments have several characteristics of rural gentrification. We conclude that the drivers of environmental degradation have changed and the degradation increased. The development projects of external companies have been rejected by the local community and have induced environmental consciousness among community members. Thus, the local community has become an advocate for sustainable land use in the study area
Development of remote sensing technology in New Zealand, part 1. Seismotectonic, structural, volcanologic and geomorphic study of New Zealand, part 2. Indigenous forest assessment, part 3. Mapping land use and environmental studies in New Zealand, part 4. New Zealand forest service LANDSAT projects, part 5. Vegetation map and landform map of Aupouri Peninsula, Northland, part 6. Geographical applications of LANDSAT mapping, part 7
The author has identified the following significant results. Inspection of pixels obtained from LANDSAT of New Zealand revealed that not only can ships and their wakes be detected, but that information on the size, state of motion, and direction of movement was inferred by calculating the total number of pixels occupied by the vessel and wake, the orientation of these pixels, and the sum of their radiance values above the background level. Computer enhanced images showing the Waimihia State Forest and much of Kaingaroa State Forest on 22 December 1975 were examined. Most major forest categories were distinguished on LANDSAT imagery. However, the LANDSAT imagery seemed to be most useful for updating and checking existing forest maps, rather than making new maps with many forest categories. Snow studies were performed using two basins: Six Mile Creek and Mt. Robert. The differences in radiance levels indicated that a greater areal snow cover in Six Mile Creek Basin with the effect of lower radiance values from vegetation/snow regions. A comparison of the two visible bands (MSS 4 and 5) demonstrate this difference for the two basins
Horizontal accuracy assessment of very high resolution Google Earth images in the city of Rome, Italy
Google Earth (GE) has recently become the focus of increasing interest and popularity
among available online virtual globes used in scientific research projects, due to the
free and easily accessed satellite imagery provided with global coverage. Nevertheless,
the uses of this service raises several research questions on the quality and uncertainty
of spatial data (e.g. positional accuracy, precision, consistency), with implications for
potential uses like data collection and validation. This paper aims to analyze the
horizontal accuracy of very high resolution (VHR) GE images in the city of Rome
(Italy) for the years 2007, 2011, and 2013. The evaluation was conducted by using
both Global Positioning System ground truth data and cadastral photogrammetric
vertex as independent check points. The validation process includes the comparison of
histograms, graph plots, tests of normality, azimuthal direction errors, and the
calculation of standard statistical parameters. The results show that GE VHR imageries
of Rome have an overall positional accuracy close to 1 m, sufficient for deriving
ground truth samples, measurements, and large-scale planimetric maps
Land use changes, landscape ecology and their socioeconomic driving forces in the Spanish Mediterranean coast (the Maresme County, 1850-2005)
We use a set of landscape metrics to study the long-term environmental transformation of a typical coastal Mediterranean area from 1850 to 2005. Our figures show a dramatic environmental deterioration between 1950 and 2005. The main proximate drivers of this landscape degradation are the effects of urban sprawl on former agricultural areas located in the coastal plains, together with the abandonment and reforestation of hilly slopes intercepted by low-density residential areas, highways, and other linear infrastructures. We carry out a statistical redundancy analysis (RDA) to identify certain ultimate socioeconomic and political drivers of these environmental impacts. The results confirm our interpretive hypothesis that: 1) land cover changes determine changes in landscape properties, both structural and functional; 2) these changes are not at random, but related to geographical endowments and socioeconomic or political drivers.statistical redundancy analysis (rda), ecological connectivity, land-use change, socioeconomic drivers, mediterranean landscapes
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