[Qgis-user] Your Bearing Distance problem

[J.O.Williams]

A couple of years ago I had the same problem verifying some 
Bearing-Distance surveys by the US governments Mineral Surveyors. The 
land was patented back in the 1872 to 1900 time frame. The townships and 
sections even now have not been surveyed.  The south-west corner of 
Colorado was surveyed using the New Mexico State Plane coordinate system 
and was surveyed in from the south and not surveyed in from eastern 
Colorado.  When the original surveyors surveyed the "probable" sections, 
the sections were off by about 1/2 mile.  The error was discovered 
because I lined up a lake on the the original plat with a modern topo. 
The lake was off by the 1/2 mile from where the plat's section lines 
were supposed to be.  The mining claims were surveyed into well surveyed 
mineral location markers.


The attached PDF is a white paper I wrote on how to verify a modern, 
year 2000+, GPS resurvey of the mining claims.  The resurvey was however 
was a partial resurvey.  Some of the claim corners were resurveyed using 
GPS, but the late 1800's  survey was very good. The other edges of the 
claim parcels could be re-plotted from the old patent plats.


I wrote some code for QGIS 2.18 for bearings and calculated a distance 
from the US BLMs GLO shapefiles.  By running the calculation scripts, I 
could compare the "new" bearing-distance" with a georef'fed PNG of the 
claim survey plat.  The calculations were also run on the tie lines to 
the Mineral Location Markers.


The biggest "gotcha" is getting the angle between the map quadrangles 
lat-long lines and the UTM coordinate lines.  The angle is available for 
the center of a topo sheet in the lower left hand corner.  That is the 
"Grid north rotation factor" discussed in Notes and or Problems number 2.


At the time this code did what I wanted it to do.  There are problems 
with rounding such as "N 15-60 W" being reformatted to "N 16-0 W".


If the attachment gets stripped please email below and I will reply.

Hope this helps.

J.O. Williams

j . o . williams . jow @@@ gmail . com




Re-Survey-Workflow.pdf
Description: Adobe PDF document
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Re: [Qgis-user] Seeking support for drill hole module

[J.O.Williams]

Greetings,

I would suggest that development also involve the Environment Superfund 
(USA) drilling projects.  The project could be sold to both groups.


TIA

J.O. Williams

On 5/19/20 12:44 AM, Andreas Neumann wrote:


Hi Grant,

Yes - Oslandia has a developed a number of plugins for geology, as 
Alexandre mentioned. You can find a video recording from FOSS4G 
Bucharest on this topic:


https://media.ccc.de/v/bucharest-244-open-source-tool-set-for-geology

I would check with them what is available and could be improved.

Greetings,

Andreas

On 2020-05-19 08:23, Alexandre Neto wrote:


Hi!
If I remember well, Oslandia team has been working on that.
I believe this is the project I seen in a conference.
https://github.com/Oslandia/albion
Best regards,
Alexandre Neto

A terça, 19/05/2020, 07:13, Grant Boxer > escreveu:


I am trying to gauge support for the development of a drill hole and
cross section plugin for QGIS. I have emailed members of my
geoscience
user group and have received about euros 3000 in initial pledges
for a
crowd funding initiative. If you would like to support this
initiative
please email me at box...@iinet.net.au
 so I can add you to my list of
supporters. In my preliminary discussions with one developer,
they have
suggested a possible expansion of the Midvatten plugin that
already has
some of the functionality required. I would be really keen to hear
opinions from other users on the best way forward for this plugin
and
with the longer term aim of having a full 3D block modelling
capability.

Regards Grant Boxer

Perth, Western Australia

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Re: [Qgis-user] Question about Weighting Power value when running Grid-Inverse Distance to a Power

[J.O.Williams]

A power of 1 is a linear interpolation among all points in the search 
radius.



A power of 2 causes the "closest point" in the search radius to have a 
slightly higher weight.



A power of 4, 6 and especially 10 causes the closest point to behave 
like a polygonal or  theissen polygon.



A power of 0.5 causes the farther away points to have a larger influence 
than closer points



The equations used only depend on the distance the points are from each 
other.  NOT the value of any of the points.  Though David has a section 
on how the variogram can be applied to IDS.



All the power IDS theory (if there is one) came out of the mining 
industry in the early 1960's because it was simple.



Hope this helps.

J.O. Williams


On 9/17/19 4:00 AM, Daniel Zepeda Rivas wrote:


When using the Raster -> Analysis -> Grid (Inverse Distance to a Power)

At the menu just before pressing run, can somebody please explain me 
the effect of the "Weighting power" option in the interpolation process?


I'm trying to make a temperature map based on points representing each 
weather station, containing the yearly averages values of temperature, 
and when moving the number from the 2 (set it by default) to 4, 6 or 
10, the map changes significantly




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