TM/ETM+Remote Sensing Image Alteration Anomaly Extraction And Filter System Development

The phenomenon of wall-rock alteration exists in vast majority of hydrothermal deposits. Locate the corresponding deposit by finding some wall-rock alteration. Remote sensing technology can extract alteration minerals by probing the spectral information of alteration rock, then delineation metallogenic belt. There are many software of remote sensing image processing to complete alteration anomaly extraction. Take Visual Studio2010.NET 3.5, secondary development components and csharp language as development platform in this paper, to meet "Remote Sense Geological Evaluation Subsystem" extraction requirements and not to use third-party remote sensing image processing software. Alteration anomaly extraction and filter system was successfully developed through using the method of removing the interference factor, principal component analysis, feature filter, feature renderer. Main results were achieved as the following:(1) The function to create and query the interpreting marks database was developed. Attribute, image and spectrum curve of the stratigraphic unit, rock unit and linear or circular structure can be stored in the symbol library, and the image information stored in the form of binary stream in the library. After the interpreting marks database has been established, users can query the details of the required marks to contrastive interpretation.(2) By developing image stretch method, achieved enhancing processing of remote sensing image, to increase the difference between the spectral characteristics of surface features and to improve interpreter the degree of visual interpretation. Band combination function has been developed, and user can achieve any combination of different bands depending on the demand. Water, vegetation and other interference information can be successfully removed by developing band operation function and generate binary image function. Principal component analysis, get a single band, extraction by threshold function has been completed to achieve extracting alteration anomaly information. Filtering alteration anomaly information can be executed by developing raster to polygon, attribute operation, feature operation, smooth function. Finally, the ferric contamination anomaly hydroxyl anomaly thematic map can be produced through setting up natural breaks renderer and equal area rendering function for the filter result.(3) Alteration anomaly extraction and filter system was designed and developed in accordance with the idea of structured and modularity, and all functions were accomplished by combining calls between interfaces. For the requirement of system function, raster operation, interpretation marks, data conversion, feature editor, attribute operation and data renderer six interfaces has been designed to system integration.(4) Alteration anomaly extraction and filter process in this paper has been tested and applied using ETM+ multispectral remote sensing data. Ferric contamination anomaly and hydroxyl anomaly information was successfully extracted, filtered and rendered. Compared with the extraction result of ENVI image processing software, the result is approximately same. The system has been proven to work.