997 research outputs found
Evaluation of the damages caused by seismic events: First tests on supporting traditional multispectral classification with DSM
Seismic damages, as a roof entirely collapsed on the ground, are very difficult to be found using only multispectral classification
algorithms. The availability of high resolution stereopairs from satellite disclose new possible fields of application to estimate
changes and transformations of areas following catastrophic events. Combining both techniques it is obviously possible only when
stereoscopic and multispectral images are available. In this case, as for all monitoring studies, it is necessary to compare the present
situation to the pre-seismic one.
The pre-seismic situation can be advantageously studied by classic photogrammetric techniques based on aerial frames, that are
available in archives managed by photogrammetric companies and local government agencies. But it is also possible to extract the
pre-seismic morphology from digital maps, containing the three-dimensional characteristics of the buildings. The present research
tries to: a) improve the digital surface model extracted from Ikonos satellite images covering an area of central Italy (Foligno,
Umbria), through a pre-treatment of images and a manual editing b) study the best DSM models to improve the detection of height
difference, mainly in urban areas, and evaluate the results of the classification of land cover as further data to detect changes in
building shape. DSM obtained by three-dimensional maps have been compared with DSM extracted directly from aerial stereo-pairs
using different approaches. In the area under study a seismic event happened in September of the '97 causing relevant damages to
different urbanized centres of the area
Thematic mapper design parameter investigation
This study simulated the multispectral data sets to be expected from three different Thematic Mapper configurations, and the ground processing of these data sets by three different resampling techniques. The simulated data sets were then evaluated by processing them for multispectral classification, and the Thematic Mapper configuration, and resampling technique which provided the best classification accuracy were identified
On-board multispectral classification study
The factors relating to onboard multispectral classification were investigated. The functions implemented in ground-based processing systems for current Earth observation sensors were reviewed. The Multispectral Scanner, Thematic Mapper, Return Beam Vidicon, and Heat Capacity Mapper were studied. The concept of classification was reviewed and extended from the ground-based image processing functions to an onboard system capable of multispectral classification. Eight different onboard configurations, each with varying amounts of ground-spacecraft interaction, were evaluated. Each configuration was evaluated in terms of turnaround time, onboard processing and storage requirements, geometric and classification accuracy, onboard complexity, and ancillary data required from the ground
Trophic classification of selected Colorado lakes
Multispectral scanner data, acquired over several Colorado lakes using LANDSAT-1 and aircraft, were used in conjunction with contact-sensed water quality data to determine the feasibility of assessing lacustrine trophic levels. A trophic state index was developed using contact-sensed data for several trophic indicators. Relationships between the digitally processed multispectral scanner data, several trophic indicators, and the trophic index were examined using a supervised multispectral classification technique and regression techniques. Statistically significant correlations exist between spectral bands, several of the trophic indicators and the trophic state index. Color-coded photomaps were generated which depict the spectral aspects of trophic state
Radiometric correction procedure study
A comparison of MSS radiometric processing techniques identified as a preferred radiometric processing technique a procedure which equalizes the mean and standard deviation of detector-specific histograms of uncalibrated scene data. Evaluation of MSS calibration data demonstrated that the relationship between detector responses is essentially linear over the range of intensities typically observed in MSS data, and that the calibration wedge data possess a high degree of temporal stability. An analysis of the preferred radiometric processing technique showed that it could be incorporated into the MDP-MSS system without a major redesign of the system, and with minimal impact on system throughput
Study of pollution at sea
There are no author-identified significant results in this report
Skylab/EREP application to ecological, geological, and oceanographic investigations of Delaware Bay
The author has identified the following significant results. Skylab/EREP S190A and S190B film products were optically enhanced and visually interpreted to extract data suitable for mapping coastal land use; inventorying wetlands vegetation; monitoring tidal conditions; observing suspended sediment patterns; charting surface currents; locating coastal fronts and water mass boundaries; monitoring industrial and municipal waste dumps in the ocean; and determining the size and flow direction of river, bay, and man-made discharge plumes. Film products were visually analyzed to identify and map ten land use and vegetation categories at a scale of 1:125,000. Thematic maps were compared with CARETS land use maps, resulting in classification accuracies of 50 to 98%. Digital tapes from S192 were used to prepare thematic land use maps. The resolutions of the S190A, S190B, and S192 systems were 20-40m, 10-20m, and 70-100m, respectively
Skylab/EREP application to ecological, geological, and oceanographic investigations of Delaware Bay
Skylab/EREP S190A and S190B film products were optically enhanced and visually interpreted to extract data suitable for; (1) mapping coastal land use; (2) inventorying wetlands vegetation; (3) monitoring tidal conditions; (4) observing suspended sediment patterns; (5) charting surface currents; (6) locating coastal fronts and water mass boundaries; (7) monitoring industrial and municipal waste dumps in the ocean; (8) determining the size and flow direction of river, bay and man-made discharge plumes; and (9) observing ship traffic. Film products were visually analyzed to identify and map ten land-use and vegetation categories at a scale of 1:125,000. Digital tapes from the multispectral scanner were used to prepare thematic maps of land use. Classification accuracies obtained by comparison of derived thematic maps of land-use with USGS-CARETS land-use maps in southern Delaware ranged from 44 percent to 100 percent
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