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PG-Prospecting

LiDAR maps and nugget shooting

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Hello everyone - 

New to the forum, been lurking for a bit though.  Im out on the East coast where gold is a bit more scarce but ive had some luck.  

LiDAR maps are becoming more widely available for free online, and that they provide fantastic data.  If you dont know what LiDAR maps are look them up.  They are an incredible resource if they are available for your area.  

For Arizona it looks like a bunch of LiDAR data has been collected in 2018 but it isnt available quite yet should hopefully be available in the next year or so.  The link below shows what is and will be available in the US

https://coast.noaa.gov/inventory/

The hardest part other then finding the LiDAR is finding programs to render the .las files into more usable DEM (Digital Elevation Model) files.  

Ive attached below some of my musings with a LiDAR map.  Basically the LiDAR helped me determine probably vein trends the old timers were working, and from that determine the areas that would have a higher probabilty of finding nuggets while detecting.  You can also extrapolate those vein trends out and hunt well out beyond the old timers working with a better probability of finding gold.  Basically it can help you the fringe hunting that Bill talks about in his videos.  

Hope this helps some people and feel free to ask questions!  Its always good to add another tool to your toolbox.  

Thanks, 

Musings.png

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Looks like raw data. Have you tried normalizing the ground elevation for ground truth and using a tensioned spline to get rid of all those artifacts?

Have you tried SPDLib or Grass to convert to DTMs? QGIS has a las toolbox but I haven't tried it yet.

Interesting shading. Do you find using slope for shading gives you better information? Looks almost metallic.

I'm glad you are getting use out of this cloud data. There is still a lot of resistance in the industry to government LIDAR data. Mining companies seem to prefer private aerial scans of particular areas with high density ground control. Good stuff to work with but really expensive.

Keep us updated on your results, I'd be interested to see what you discover on the ground.

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I don't use SPDLib but I have tried Grass and it is groovy. I find it is good for a tensioned spline. 

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Clay - 

I mainly use SAGA gis on available DEMs, and i was using Whitebox GAT to turn .las files into DEM files but it would take a few days to process one tile and wouldnt work alot of the time.  Ive only just started using QGIS but the newest version no longer supports the las tool box.  

What artifacts are you referring too?  Ive been to that site and what i see on the map is what i see on the ground.   I will say ive generally managed to get what i want out of the programs but i still really dont know what most of the features do.  

 

Ive found that hillshading helps me the most and ive be accustomed to it to the point where i can read it like a topo map.  Ive also messed around with terrain roughness index which brings out certain features better.  

 

I will look into SPDLib, i havent heard of it before.  

 

Below is another example, hill shaded with color to indicate elevation as well as 5 foot contour intervals.  

 

Thanks

Capture.PNG

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I'm glad I saw this.  LiDar has come a long way since I first saw it many years ago. 

I think google somehow combines the LiDar images with imagery to get the 3D didplay

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Would love to get a file of my claim area. I'll be following this closely.

I think some work was done associated with asbestos veins and fault lines here. 

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LiDAR has some potential for looking for old timer digs. I looked at what’s available with hope that my claims in Southern AZ would be covered, but not yet. Would be cool to use LiDAR to spot old timer pot holes and trails. Ive had luck finding gold following old overgrown trails that lead into the mountains.

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Posted (edited)
18 hours ago, chrisski said:

I'm glad I saw this.  LiDar has come a long way since I first saw it many years ago. 

I think google somehow combines the LiDar images with imagery to get the 3D didplay

Google just uses regular 30 meter resolution DEMs Chris - no LIDAR. The "3D" effect on buildings and trees is a result of photogrammetry extrapolation from off angle aerial photos. That's why the trees look so funky and buildings often look "wavy".

Apple just recently revealed they have spent the last 4 years doing ground level high resolution LIDAR scans and 3D photography from surface vehicles. They have now created a true 3D LIDAR based interactive map of the United States. I've seen the results and they are truly amazing. Google's 3D mapping days are numbered, when you see this new technology you will wonder why you thought Google 3D was cool.

Edited by clay
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Posted (edited)
20 hours ago, PG-Prospecting said:

Clay - 

I mainly use SAGA gis on available DEMs, and i was using Whitebox GAT to turn .las files into DEM files but it would take a few days to process one tile and wouldnt work alot of the time.  Ive only just started using QGIS but the newest version no longer supports the las tool box.  

What artifacts are you referring too?  Ive been to that site and what i see on the map is what i see on the ground.   I will say ive generally managed to get what i want out of the programs but i still really dont know what most of the features do.  

 

Ive found that hillshading helps me the most and ive be accustomed to it to the point where i can read it like a topo map.  Ive also messed around with terrain roughness index which brings out certain features better.  

 

I will look into SPDLib, i havent heard of it before.

Thanks

Thanks for the reply PG-Prospecting.

I haven't had much luck with SAGA except from the command line. SAGA runs on R code just like GRASS so it is possible to speed things up bypassing the clunky GUI. If I've got to use R for a process I'm more familiar and confident in GRASS. Since QGIS has achieved high integration with GRASS it's pretty easy to switch to GRASS command line while still having the advantages of a stable working platform. Most GRASS functions are available directly through QGIS without any need to use code.

You could install an older version of QGIS that supports the las toolbox. QGIS can run multiple versions on most operating systems. I run several versions of QGIS just so I can use different tool sets on different projects. Each version has it's own strengths and weaknesses.

The artifacts are the thin parallel scan lines running north/south, the terracing on steep slopes and the lack of ground truth extraction. All that is why most people would prefer processed LIDAR instead of raw cloud data. The real advantage to LIDAR in mapping is not so much in a bumped resolution but in it's true 3D location data. Flat maps with higher surface resolution are nice but I'm of the opinion that giving a more human point of view is the ultimate reason LIDAR will be adopted on a level like aerial photography is now. 3D interactive viewing is still in it's infancy but people are adopting it as soon as it's available. See my post above about Google Earth and Apple Maps as an example.

Hillshading is pretty much necessary when presenting flat terrain maps. I like using a Northwest Angle with a medium Azimuth for flat presentation. Hillshade can be problematic when presenting 3D interactive maps. False shadows can look odd from some angles. I'm learning to use a lighter hand on the hillshade when creating 3D interactives but I've not yet been entirely happy with my results. I've employed real time relational shading on some 3D interactives and that looks really good but for the internet and your average home computer the size and processing requirements are prohibitive.

If you are creating these maps for your own use consider looking into D3.js. It can do some pretty cool 3D interactive processing with minimal processor load. Your maps could provide a lot more visual information with a 3D interactive component.

 

Edited by clay
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