Extraction of the Lineaments From Enhanced Directional Images

By Tito S.L. Soempono
June 19, 1999, 4:25 p.m. AST

Landsat Thematic Mapper image data commonly are used for various analysis in applying geosciences. I often use the composite bands of TM for geologic analysis, interpretation, and mapping. This page shows a directional enhanced satellite image derived from band 4 of TM infra-red image (0.8 to 1.1 µm), and this is resulted by merging from, the results of analysis, directional images for four main compass directions, i.e. Northwest-Southeast, North-South, Northeast-Southwest, and East-West. or analysis of geologic structures

The lineaments are appeared as dark features.

Lineaments: Features of Geologic Structures

The features of lineaments are able to be identified visually on remotely sensed images. The lineaments are linear, rectiliniear or slightly curvilinear surface features that indicating the fractures of rocks or the bedding traces of sedimentary rocks where dissecting of the land surface was occured. Rock fractures, the faults and joints, commonly provide key to occurence of groundwater, minerals, and petroleum. They are important in delineation of the region with geological hazard risks as a zone of weakness where earthquakes or landslides may be occured. In the hydrogeologic view, the fractured rocks having highly risks of ground water pollution (pollution suscceptibility). These features presumably reflects the subsurface phenomena below them.

The lineaments visually can be interpreted on an image as faults or bedding, and they clearly appeared in a composite of infra-red images (Thematic Mapper R=Band4 G=Band5 B=Band7). This composite show a dissected terrain of Tertiary sedimentary formations and Quarternary volcanic rocks in Sumedang area, about 60 kilometres to the east from Bandung City.

Directional Enhanced Image derived from Band 4 of Thematic Mapper

The features of lineaments on the land surface, as appeared in the image, formed by a variety of interpretable image elements, including alignments of topographic relief, drainages, vegetations, and soil/rock tones.

Lineaments are mapable, simple or composite linear features of a land surface, whose parts are aligned in a rectiliniear or slightly curvilinear relationship and which differs distinctly from the patterns of the adjacent features.

Lineaments commonly are indicated by edge and line segments in a satelite images. The edge and line segments in digital satellite images can be enhanced by applying convolution and stretching/compression methods in preferred orientation of compass directions. Classification and/or logical operation applied in the algorithms of extraction resulting extracted lineaments, then the results can be converted to vector data of GIS.