Finding better locations for gold detecting using Lidar
(Light Detection and Ranging) Mapping and Google Earth
What is LiDAR?
Lidar is a remote sensing surveying method that measures the distance to a target by illuminating the target with laser light and measuring the reflected light with a sensor (from Wikipedia). Differences in laser return times and wavelengths can then be used to make digital 3-D representations of the target – so it is some times referred to as 3D laser scanning. The surveys are usually carried out by light aircraft or a drone.
How do we use LiDAR in Gold Detecting?
We look a ground features and geology to understand past gold prospecting and mine activity. Due to their scale, these features can be difficult to spot from ground level, and they can be even harder to see in most remotely sensed imagery if obscured by vegetation or loose sediment. Geologists can interpret the pattern and direction of these surface features and, as many gold deposits are associated with geological structures, use this information when selecting and prioritizing exploration targets.”
For the gold prospector and metal detectorist you can analyse LiDAR maps and compare them to Google Earth to select and prioritise your own expeditions.
How accurate is it? Less than 2m
Since 2018, it has been slowly growing in popular amongst those prospectors who are able to convert and analyse the GIS data. The programs are complicated to learn (and becoming easier all the time) and there is so much free LiDAR data to learn from.
What does the data show? The ground return from the lidar is the return that shows a bare earth model of the existing ground surface. Google earth program has no compatibility with normal lidar data. To make it usable on google earth one has take the .las format and render it into a DEM which is generally a .tif file, then from there you need the right program to turn the .tif into a georeferenced kml or kmz file which overlays in google earth. It is not an easy or straight forward process.
How does it work? Watch this video from PG Prospecting to understand the process of producing your first map: https://www.youtube.com/watch?v=0Hy2phFsrhI&t=67s (new video from February 2020).
Original video from 2019: https://youtu.be/CHOf4-EHH5A
New 2020 video: https://youtu.be/0Hy2phFsrhI
Matt is a geologist from the USA and has made a fantastic video that shows some the uses and benefits of lidar maps for the gold prospector and metal detectorist. His new website from 2020 is https://theprospectinggeologist.com/
The lidar data files can be integrated into Google Earth Pro where Lidar imagery can be turned on or off by clicking the box to the left of the file name. Using GE allows measuring distances and pinpointing GPS coordinates. Depending on your location and what Lidar data may be available you may need a program to convert .LAS files to DEM files.
Some World Wide Resources:
UK Lidar site: https://www.lidarfinder.com/
Live Australia data is available free online: https://ecat.ga.gov.au/geonetwork/srv/eng/catalog.search?node=srv#/metadata/89644
Done in 2001.
Aussie Bloke Prospecting Adventures ‘TENGRAPH’ video: https://youtu.be/_AGtQ8hlDAY
Downloading Current (Live & Pending) Tenements for WA
Oregon Lidar viewer: https://gis.dogami.oregon.gov/maps/lidarviewer/
Comments from prospectors in 2019 using LiDAR:
“It has been a huge help with prospecting and figuring out what the old timers were doing at the old mines. “
“I’ve been looking for coverage of the Victorian Goldfields for ages but haven’t found any available publicly.”
Things are getting better all the time. I hope to get more articles from PG Prospecting talking about using remote sensing data for gold prospecting.