Up to now, aerial photographs have almost been the unique data sources to be used for the purpose of urban spatial data acquisition. Recently, great attention has been paid to the emergence of high resolution satellite imagery (resolution around 1 meter) . Huge benefits may be reached if the so-called high resolution satellite data can be used as the data source for urban spatial data acquisition, especially for building related information collection. In this paper, the characteristics of high resolution satellite imagery are analyzed at first. Two practical building extraction methods are then proposed. One method aims to extract buildings with image features (edges and corners) extracted from high resolution satellite images, while the other tries to extract buildings with region growing algorithm. Experiments are carried out for testing the efficiencies of proposed two building extraction methods. Since high resolution satellite images are still not available at the moment, three different types of simulation images with different resolutions (0.5m, lm and 3m, respectively) made from aerial photographs are used in experiments.
There has been a large amount of slash and burn agricultural activity from ancient times in Northern Laos. This study focuses the environmental impact of slash and burn on the forest ecology by mean of spatial and temporal analysis of high resolution satellite data. A Geographic Information System (GIS) was also used for analyzing the relationship between the slash and burn and forest vegetation, topography and social factors. Then, the sustainability of slash and burn was examined by the ecological analysis of the shifting pattern and fallow duration derived from the image interpretation. As a result of study, a total of 89, 000 ha of slash and burn fields within 172, 000 ha of fallow lands were detected during the past 10 years. Although the recent increase of population pressure caused an expansion of slash and burn fields (11, 000 ha in 1987 to 19, 000 ha in 1997), most parts (80%) of those fields are still maintaining the traditional conditions of having more than 7 years fallow duration. It can be said that such slash and burn is sustainable because of its ecologically balanced cycle of cultivation. Based on the analysis, it is concluded that slash and burn agriculture is not always a cause of environmental deterioration in the study area. More important is the introduction of a well managed methodology of forest resources for future sustainable development. In this sense, it can be recommended that remote sensing and GIS technology play a more important role in the monitoring of slash and burn agricultural practices.
Omura Bay in Nagasaki Prefecture, which is connected with the open sea through Sasebo Bay, is called a double-closed bay. It is also an obstacle for a tidal current of Omura Bay that there are very narrow channels between these bays. Satellite remote sensing technique was applied to the visualization of the seawater plume in Omura Bay. The plumes show the current from surface to the depth of a few meters, as Landsat5/TM data have relation to the seawater quality in the same area. The plumes were investigated with the tide of the bay. It follows that the direction of incoming seawater is the same as the topographical direction of Hario Channel, and that there is a tidal residual current between Hario Channel and Ohsaki Peninsula. Lastly the observation by using current meters was also shown to back up these movements of the plumes.
It is necessary for fully automatic relative orientation to realize precise and stable detection of tie points in stereo images. However, usual approaches such as template matching are not applicable to images of different conditions because parameters depend on features of images strongly. In this paper we proposed a series of techniques based on combination of probabilistic relaxation method and gradient method. By our approach, insensibility on setting parameters is achieved in individual methods and as a result total process is more robust. In addition, by examining detected points using relative orientation equation, it is possible to select points that satisfy required accuracy. The validity of proposed technique was verified by experiments using differently
The authors have been concentrating on developing a real-time ortho imaging, drawing and modeling system for a recording system of relics using a CCD camera and line lasers. There are still, however, some issues which need to be resolved before this system may become operational. These problems include imaging for shadow areas occurring in hollow areas on complicated relics or faint areas at the top of columnar relics and lack of an exquisiteness for an edged image for a drawing. This paper describes an imaging approach for these shadow and faint areas synthesizing an ortho and a central projection image which are taken using a color CCD camera. The most remarkable points of this approach are its ability to obtain a color ortho projection image and a color 3D model. As for further additional results of this system, visualization of relics from several view points can be achieved on the computer using an animation technique. Some virtual archeological examples are demonstrated in this paper.
Land cover and use classification on a huge scale, e. g. national or continental scale, has become more and more important because environmental researches need land cover and use data on such scales. We developed a crop field extraction method, which is one of the steps in our land cover classification system for a huge area. Firstly, a crop field model is defined to characterize“crop field”in terms of NDVI value and textual information. Textual information is represented by the density of straight lines which are extracted by wavelet transform. Secondly, candidates of NDVI threshold value are determined by“scale-space filtering”method. The most appropriate threshold value among the candidates is determined by evaluating the line density of the area extracted by the threshold value according to the crop field model. The crop field is extracted by applying level slicing to Landsat TM image with the threshold value determined above. The experiment demonstrates that the extracted area by this method coincides very well with the one extracted by visual interpretation.
Due to the rapid growth of city, spatial management by men is becoming increasingly difficult and therefore expectation toward GIS capability is growing larger and larger now. In order to expand the usage of GIS, cost cut for digitization of map data is indispensable. In this report, the applicability of high resolution satellite images to GIS is examined by the interpretation of simulated images.
This study propose the new replication method for the ancient artifacts excavated, using Digital Photogrammetry, 3D modeling, Stereolithography. By testing the replica which is applied this method, I could verify enough accuracy and economical effect on the target of“making replica”. Moreover, the generalization of 3D measurement using digital image may have great possibility to change the method in archaeology drastically, which has been applied so far for documentation and utilization of newly found sites and artifacts. It is urgently necessary for us to have a new understanding of photograph, which is fundamental for those methods, as it should be more detailed and precise than before.