Visual Interpretation Of Aerial Photographs Research Articles

Application of an incomplete landslide inventory, logistic regression model and its validation for landslide susceptibility mapping related to the May 12, 2008 Wenchuan earthquake of China

The main purpose of this paper is to present the use of multi-resource remote sensing data, an incomplete landslide inventory, GIS technique and logistic regression model for landslide susceptibility mapping related to the May 12, 2008 Wenchuan earthquake of China. Landslide location polygons were delineated from visual interpretation of aerial photographs, satellite images in high resolutions, and verified by selecting field investigations. Eight factors, including slope angle, slope aspect, elevation, distance from drainages, distance from roads, distance from main faults, seismic intensity and lithology were selected as controlling factors for earthquake-triggered landslide susceptibility mapping. Qualitative susceptibility analyses were carried out using the map overlaying techniques in GIS platform. The validation result showed a success rate of 82.751 % between the susceptibility probability index map and the location of the initial landslide inventory. The predictive rate of 86.930 % was obtained by comparing the additional landslide polygons and the landslide susceptibility probability index map. Both the success rate and the predictive rate show sufficient agreement between the landslide susceptibility map and the existing landslide data, and good predictive power for spatial prediction of the earthquake-triggered landslides.

Estimating soil sealing rate at national level—Italy as a case study

Soil sealing has been regarded as a key environmental problem since sealed soils lose several of their functions determining a reduction in land productivity and quality. Unfortunately, the analysis of changes in land-use carried out through the use of traditional data sources allows a relatively rough estimation of this phenomenon. The aim of this paper is to illustrate a procedure quantifying over time the soil sealing rate at the country scale. Italy was chosen as the study area due to its spatially-complex urbanization patterns. The procedure was based on the visual interpretation of aerial photographs and high-resolution topographic maps taken at four points in time (1956, 1994, 1999, 2006) in a random sample of field plots homogeneously distributed across the country. Results indicate that soil sealing continuously increased in Italy over the investigated period with the highest absolute and per-capita growth rate of sealed areas being observed respectively in northern and southern Italy. Compared to past, per-capita soil sealing was higher in the most recent period (1999–2006).

Influence of Near‐to‐Nature Stormwater Management on the Local Water Balance Using the Example of an Urban Development Area

Near-to-nature stormwater management aims at replicating the quasi-natural local water balance and preserving the ecosystem's integrity of affected waters. Surface waters in the urban areas of Trier-Petrisberg are managed by a separate sewer system in conjunction with a complex retention system. To investigate the effect of this alternative rainwater management practice on the local water balance, a differentiated discharge and groundwater monitoring network with a high spatio-temporal measurement resolution has been implemented within the watershed. Additional information regarding the proportion and spatial distribution of discharge-generating surfaces was provided through visual interpretation of aerial photographs. As a result of this analysis, groundwater levels were found to not be significantly affected by an increase of local sealed surfaces, and the ecologically-justifiable maximum discharge in the tributary was infrequently exceeded. Regarding further building development and climate change, the hydrological load capacity of the retention basins will provide effective rainwater management, even with respect to increasing precipitation intensities and frequencies.

Differences in land cover interpretation in landscapes rich in cover gradients: reflections based on the montado of South Portugal

This paper contributes to the discussion on current issues in methodologies of mapping land cover in the agro-silvo-pastoral landscapes of the Mediterranean. These landscapes, characterized by intermixed land use and indefinite boundaries, require particular attention in applying the patch-corridor-matrix model when classifying patches and their delineation. In a case study area in southeast Portugal, mainly characterized by agro-silvo pastoral systems, the land cover for 1990 has been mapped. The paper discusses the consequences of the complexity of some Mediterranean land use systems for land cover mapping dealing with detailed landscape dynamics. Within this scope a land cover mapping project in a small case study area is compared with the mapping undertaken within a national land cover database. Both studies were carried out on the same scale and through visual interpretation of aerial photographs. Differences in land cover classification and allocation are explored using matrix with levels of agreement. Recommendations for future land cover mapping projects are: the application of fuzzy approaches to land cover mapping in agro-silvo-pastoral landscapes should be explored and land cover classifications should be standardized in order to enhance consistency between databases. On the other hand, the fuzziness of the boundaries in this kind of landscapes is inherent to the system and should be accepted as such. The accompanying uncertainties should be taken into account when undertaking landscape analysis on the basis of land cover data.

Object-oriented methods for habitat mapping at multiple scales – Case studies from Northern Germany and Wye Downs, UK

This paper presents an application of object-oriented techniques for habitat classification based on remotely sensed images and ancillary data. The study reports the results of habitat mapping at multiple scales using Earth Observation (EO) data at various spatial resolutions and multi temporal acquisition dates. We investigate the role of object texture and context in classification as well as the value of integrating knowledge from ancillary data sources. Habitat maps were produced at regional and local scales in two case studies; Schleswig-Holstein, Germany and Wye Downs, United Kingdom. At the regional scale, the main task was the development of a consistent object-oriented classification scheme that is transferable to satellite images for other years. This is demonstrated for a time series of Landsat TM/ETM+ scenes. At the local scale, investigations focus on the development of appropriate object-oriented rule networks for the detailed mapping of habitats, e.g. dry grasslands and wetlands using very high resolution satellite and airborne scanner images. The results are evaluated using statistical accuracy assessment and visual comparison with traditional field-based habitat maps. Whereas the application of traditional pixel-based classification result in a pixelised (salt and pepper) representation of land cover, the object-based classification technique result in solid habitat objects allowing easy integration into a vector-GIS for further analysis. The level of detail obtained at the local scale is comparable to that achieved by visual interpretation of aerial photographs or field-based mapping and also retains spatially explicit, fine scale information such as scrub encroachment or ecotone patterns within habitats.

Updating stand level inventory data applying growth models and visual interpretation of aerial photographs

In this study two procedures for updating stand level inventory data were developed and tested. The development of the growing stock of 62 stands over 12 years was simulated in the MELA stand simulator with no prior information of rapid changes, such as clear-cuttings. The acceptability of the simulation was decided standwise with visual interpretation of aerial false-colour photographs. If the simulated data were not accepted, new stand attributes were assessed with photo interpretation in procedure 1. In procedure 2, on the other hand, it was possible to utilise old management proposals. In case a cutting or other operation had been proposed and it looked like the operation had been realised, the interpreters accepted the proposal. Otherwise the last implemented operation and implementation year were interpreted. In case no operation had been carried out during the updating period but the growth model updated data were not acceptable, the same stand characteristics were estimated as in procedure 1. Stands where a proposal had been accepted or an operation interpreted were later updated again in MELA so that the program simulated the operations. The Root Mean Squared Errors of stem volume were 62 and 57 m3 per ha (34 and 30%) with procedures 1 and 2. With procedure 2 the accuracy of updating was comparable with a stand level field inventory carried out in the study area. The productivity of the photo interpretation procedures was 57 and 84 ha per h, respectively, whereas the productivity of a field inventory has been 3.3–5 ha per h.

Holistic aspects of suburban landscapes: visual image interpretation and landscape metrics

Holism deals with extremely complex structures that are difficult to analyse. The holistic approach of landscape research was stimulated by the introduction of aerial photography. Carl Troll called “aerial photo-interpretation as a high degree of landscape ecology,” which illustrates the intimate link between the bio-philosophical theory of holism and the Gestalt-theory of human perception, which is important in image interpretation. Aerial photography proved to be a valuable instrument, not only to make thematic inventories and monitor changes, but also to describe holistic aspects of complex landscapes. Contrarily, the analytical approach aims to describe transcendent characteristics of complex structures by quantitative variables. Many landscape metrics have been proposed and used, such as entropy as an indicator of fragmentation and heterogeneity. A comparison was made between a typology and classification of a highly complex suburban landscape with aid of a holistic-based approach for visual interpretation of aerial photographs and a quantitative approach using landscape metrics of the patches formed by the land use. The study area covers the suburban transition of the city of Ghent (Flanders, Belgium) to the rural countryside to the west and is characterised by a large diversity of land use and a severe fragmentation of infrastructures. The visual interpretation of aerial photographs allowed rapid and easy classification into 10 distinct and landscape types, which could be mapped. The landscape metrics used were patch area, patch shape, fractal dimension of the patch borders and two forms of information entropy. The metrics were derived from the land use map based upon a supervised classification of satellite data and improved by ancillary data with a resolution of 20 m. Overall, the fractal dimension and entropy are significantly different for the landscape types, while those for the patch area and shape are not. Landscape metrics are very sensitive to data quality, particularly in complex and very heterogeneous landscapes. Interpretation of the results is also made more difficult due to the effects caused by the algorithms of spatial analysis used to determine patches, and due to the noise added by index calculation. These effects are reflected on maps representing the distribution of the landscape metrics. The patterns revealed here depend largely upon the method of classification and visualisation. The summed entropy corresponds most closely to the landscape units defined by visual image interpretation. It can be used as a quantitative characteristic of holistically defined landscape units.