Mapping of Geological Lineaments from Different Sun Elevation Angles Using Digital Elevation Model (DEM): A Case Study of Nigeria Geology Map Series Sheet 135 (Duhu Sheet)

The study focuses on the mapping of geological lineaments from the following different sun elevation angles: 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° of the Digital Elevation Model (DEM). Four of the images with azimuth; 0°, 45°, 90° and 135° were combined to produce a single image with multi-illumination directions. The images with azimuth; 180°, 225°, 270°, and 315° were equally combined to produce another single shaded relief image with multi-illumination directions. The two multi-illumination direction images were used for the automatic lineament extraction using PCI Geomatica software. The extracted lineaments were overlaid, and duplicate lineaments were eliminated. The final lineaments of the study area were screened using high-resolution Google images for non-geological features. A total of 237 lineaments were extracted, with a total length of 649.77Km, a mean length of 2.742Km and standard deviation of 1.187. The dominant trending pattern in the final lineaments of the study area is NE-SW direction. The Lineament density for the study area ranges from 0 to 1.36 km/sqkm with about 69.1% of the study area being mapped as poor and low density while the high and very high densities area account for just about 30.9% of the study area.