Lineament Analysis
GDLT
Global Mapper User
Is automated lineament analysis possible in Global Mapper?
Comments
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Would lineaments typically be found along lines of steep slope or something like that? There isn't currently a way to do this in Global Mapper, but I did some research and found some good prospects for algorithmic lineament extraction from imagery http://www.bgu.ac.il/bidr/research/phys/remote/Papers/1996-Karnieli_Hough_PERS_96.pdf. Is that what you are looking for? If so I have added an internal task item (#12627) for it.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Global Mapper -
Exactly that. It is a fairly common part of a geological workflow to identify linear features on a regional scale as they often correlate well with major fault and fracture structures.
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Ok thanks for the confirmation. Hopefully we can add it to the analysis tools in a future release.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Global Mapper -
Is automated lineament analysis possible in Global Mapper?
It could depend on what type of lineament you are referring to.
Lineaments may be single (or a limited set) of discrete fault(s) such as the San Andreas and the surrounding system of faults; or can they can be sets of fractures that criss-cross an area in certain directions due to stress relief as erosion removes the overlying weight of rock. In areas where bedrock is exposed, 2 to 3 sets having generally consistent trends are often easily recognisable.
Which type of lineament are you looking recognise?
Either way, as fractures these lineaments weather easily and so will coincide with valley/gully bottoms, and are most noticeable when the valleys are continuous, deep and/or steep-sided. I am not sure about the automation process in GIS, but some level of human interaction (or setting of thresholds in the automated process) may be required as other geological features or scenarios may produce false results (e.g. where geological bedding is vertical and includes some shales which weather very easily).
Albs -
Mike
Another way of detecting potential lineaments is from topographic data. Narrow, steep-sided, relatively straight valleys/gullys are easy to recognise on contour maps or shaded DEMs.
Could an algorithm to trace the bottom of these valleys from an elevation grid work if the data set is topographic? I assume it would not be too different to the algorithm that generates streams with the watershed analysis tool. -
The watershed analysis to generate streams sounds like exactly that. It basically just follows where water would flow downhill, so it would naturally end up in valleys. So you could do some rudimentary lineaments perhaps just from that.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
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