Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “change detection”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6

Automated thematic mapping and change detection of ERTS-1 images

Results of an automated thematic mapping investigation using ERTS-1 MSS images are presented. A diffraction pattern analysis of MSS images led to the development of spatial signatures for farm land, urban areas, and mountains. Four spatial features are employed to describe the spatial characteristics of image cells in the digital data. Three spectral features are combined with the spatial features to form a seven dimensional vector describing each cell. Then, the classification of the feature vectors is accomplished by using the maximum likelihood criterion. Three ERTS-1 images from the Phoenix, Arizona area were processed, and recognition rates between 85% and 100% were obtained for the terrain classes of desert, farms, mountains and urban areas. To eliminate the need for training data, a new clustering algorithm has also been developed.

Gramenopoulos, N.↗

Automated thematic mapping and change detection of ERTS-A images

The author has identified the following significant results. In the first part of the investigation, spatial and spectral features were developed which were employed to automatically recognize terrain features through a clustering algorithm. In this part of the investigation, the size of the cell which is the number of digital picture elements used for computing the spatial and spectral features was varied. It was determined that the accuracy of terrain recognition decreases slowly as the cell size is reduced and coincides with increased cluster diffuseness. It was also proven that a cell size of 17 x 17 pixels when used with the clustering algorithm results in high recognition rates for major terrain classes. ERTS-1 data from five diverse geographic regions of the United States were processed through the clustering algorithm with 17 x 17 pixel cells. Simple land use maps were produced and the average terrain recognition accuracy was 82 percent.

Gramenopoulos, N.↗

Active Volcanoes of Kamchatka as Suitable Terrestrial Analogs for Future Landing Missions and for Change Detection Analysis on Venus

The next decade will see the return to Venus due to a number of missions which have been recently selected and proposed for launch. The selected missions NASA DAVINCI and VERITAS, Roscosmos Venera-D, and ESA EnVision, along with the proposed missions ISRO Shukrayaan- 1, and CNSA VOICE, will open a new era for the exploration of the Earth’s hellish twin planet. These missions will shed new light on the science questions such as: (a) whether recent volcanic activity is locally constrained, or active volcanism occurs on a global scale; (b) the rate of the present-day volcanic activity; (c) the styles of volcanism on Venus, including possible occurrences of pyroclastic/explosive volcanism; and (d) how does the extreme environment on Venus effect volcanic activity. In preparation for these future missions to Venus, the Analogs for VENus’ GEologically Recent Surfaces (AVENGERS) initiative has the scope to select and analyze a number of active terrestrial volcanoes as suitable analogs for the identification and analysis of active volcanism on Venus. The Roscosmos Venera-D is the only mission, among the currently selected or planned mission, equipped with a lander to analyze the elemental and mineralogical composition of the surface. Therefore, it is crucial to find applicable volcanic areas on Earth to perform operational tests such as surface drilling and in-situ elemental composition analysis. To this regard, we propose the analysis of active volcanoes of the Kamchatka Peninsula, which is in a geodynamic setting (subduction) contrasting to that of the volcanic rises on Venus (hot spot). Thus, Kamchatka may represent a helpful geodynamic endmember to put the expected landing site of the Venera-D mission within the context of the entire variety of volcanic landforms and surface chemistry. The Kamchatka Peninsula is located on the eastern margin of the Eurasian plate, in proximity to the Kuril-Kamchatka subduction zone. The frequent eruptions characterizing the volcanoes of the Kamchatka Peninsula make them a suitable terrestrial analog for the possible detection of ongoing eruptions on Venus by future missions, which can be achieved by comparing a sequence of radar images of the same volcano and its surroundings taken at different times. Moreover, it is possible to collect samples of both unweathered and weathered volcanic deposits, to analyze their near infrared spectra in the laboratory for direct comparison with the spectra to be provided by the future missions to Venus. The chemical analyses of Venusian surface materials from the previous Soviet Venera and Vega missions are consistent with that of tholeiitic basalts. Since the volcanism of the Kamchatka Peninsula is characterized by both basaltic lava flows eruptions and pyroclastic activity, performing operational tests in the Kamchatka Peninsula also offers the unique opportunity to provide us the tools to potentially interpret the diverse output given by both effusive and explosive volcanic products.

Piero D'Incecco↗