Lineament Extraction

Overview

Lineaments are mappable straight or gently curved features of the surface whose parts are aligned, and which differ from the pattern around them; they presumably reflect structures below the surface (O’Leary et al. 1976). On an elevation model they appear as straight valleys, ridges, scarps and aligned breaks of slope. A single light hides the features parallel to it, so the terrain is shaded from 0°, 45°, 90° and 135° under a low (30°) sun; each cell keeps the strongest edge of the four lights.

Edges are found with the Canny detector, thinned to one-cell curves, traced, simplified and cut where they bend more than 30°, so that every piece is close to straight. Pieces of one lineament broken by saddles, gullies or landslides are then linked when they keep the same direction and the gap is short, which turns scattered fragments into continuous lineaments; parallel twin edges of one landform are merged. This follows the LINE procedure used in PCI Geomatica and the studies that apply it to shaded DEMs.

Every lineament is then read against the elevations: the mean cross-section shows whether it is a valley (lower than both sides), a ridge (higher than both), a scarp (a step with one side lower, the downthrown side) or a line on a slope, with its relief and width. Longer lineaments, especially those marked by wide and deeply cut zones, usually belong to faults that reach deeper, while short ones are mostly joints; the tool groups them into local, intermediate, major and regional classes and gives an order-of-magnitude depth reach. Where a lineament separates different rock units on the geological map, or the units stop at it and reappear shifted, a fault is likely.

What you enter · What you get

How it works in the field

Method and equations

Accuracy and error limits

• Position: about one cell (30–90 m depending on the area); a line moved onto a valley floor or crest is within half a cell of it. Trend: ±3–5° for lineaments longer than 1 km, worse for short ones. Relief and width: the elevation model is accurate to about 2–4 m vertically, so steps under about 5 m and widths under two cells are not reliable.
• Completeness: features parallel to all four lights are rare, but lineaments in flat plains, under dense forest or across towns may be missed, and roads, canals, field edges and bedding of folded layers produce lines that are not faults. The depth reach is an order of magnitude only (a factor of 2–3).
• To reduce the error: use the fine cell size for small areas, raise the minimum length in folded mountains, compare the result with the geological map background and the active faults, check the main lineaments on imagery, and confirm the important ones in the field (fault planes, breccia, slickensides, offset beds).

Who uses it

Standards and references

1. Hobbs, W.H. (1904). Lineaments of the Atlantic border region. Geological Society of America Bulletin, 15, 483–506.
2. O’Leary, D.W., Friedman, J.D. & Pohn, H.A. (1976). Lineament, linear, lineation: some proposed new standards for old terms. GSA Bulletin, 87, 1463–1469.
3. Canny, J. (1986). A computational approach to edge detection. IEEE Transactions on Pattern Analysis and Machine Intelligence, 8(6), 679–698.
4. Zhang, T.Y. & Suen, C.Y. (1984). A fast parallel algorithm for thinning digital patterns. Communications of the ACM, 27(3), 236–239.
5. Douglas, D.H. & Peucker, T.K. (1973). Algorithms for the reduction of the number of points required to represent a digitized line or its caricature. Cartographica, 10(2), 112–122.
6. PCI Geomatics. Geomatica Help: LINE — lineament extraction (parameters RADI, GTHR, LTHR, FTHR, ATHR, DTHR).
7. Abdullah, A., Akhir, J.M. & Abdullah, I. (2010). Automatic mapping of lineaments using shaded relief images derived from digital elevation model (DEMs) in the Maran–Sungi Lembing area, Malaysia. Electronic Journal of Geotechnical Engineering, 15, 949–958.
8. Masoud, A. & Koike, K. (2006). Tectonic architecture through Landsat-7 ETM+/SRTM DEM-derived lineaments and relationship to the hydrogeologic setting in Siwa region, NW Egypt. Journal of African Earth Sciences, 45, 467–477.
9. Masoud, A.A. & Koike, K. (2011). Auto-detection and integration of tectonically significant lineaments from SRTM DEM and remotely-sensed geophysical data. ISPRS Journal of Photogrammetry and Remote Sensing, 66, 818–832.
10. Scheiber, T., Fredin, O., Viola, G. et al. (2015). Manual extraction of bedrock lineaments from high-resolution LiDAR data: methodological bias and human perception. GFF, 137(4), 362–372.
11. Nicol, A., Watterson, J., Walsh, J.J. & Childs, C. (1996). The shapes, major axis orientations and displacement patterns of fault surfaces. Journal of Structural Geology, 18, 235–248.
12. Schultz, R.A. & Fossen, H. (2002). Displacement–length scaling in three dimensions: the importance of aspect ratio and application to deformation bands. Journal of Structural Geology, 24, 1389–1411.
13. Wood, J. (1996). The Geomorphological Characterisation of Digital Elevation Models. PhD thesis, University of Leicester.
14. Mardia, K.V. & Jupp, P.E. (2000). Directional Statistics. Wiley, Chichester.
15. Copernicus DEM GLO-30, served by the Microsoft Planetary Computer; geological map units from Macrostrat (CC BY 4.0); active faults from the GEM Global Active Faults Database (CC BY-SA 4.0).