Shallow Thoughts : : mapping
Akkana's Musings on Open Source Computing and Technology, Science, and Nature.
Thu, 01 Aug 2024
I was talking to a friend about LANL's proposed new powerline.
A lot of people are opposing it because
the line would run through the Caja del Rio, an open-space
piñon-juniper area adjacent to Santa Fe which is owned by the
US Forest Service.
The proposed powerline would run from the Caja across the Rio Grande to the Lab.
It would carry not just power but also a broadband fiber line, something
Los Alamos town, if not the Lab, needs badly.
On the other hand, those opposed worry about
road-building and habitat destruction in the Caja.
I'm always puzzled reading accounts of the debate. There already is a
powerline running through the Caja and across the Rio via Powerline Point.
The discussions never say (a) whether the proposed
line would take a different route, and if so, (b) Why? why can't they
just tack on some more lines to the towers along the existing route?
For instance, in the slides from one of the public meetings, the
map
on slide 9
not only doesn't show the existing powerline, but also
uses a basemap that has no borders and NO ROADS. Why would you use a
map that doesn't show roads unless you're deliberately trying to
confuse people?
Read more ...
Tags: mapping, GIS, programming, python, Los Alamos
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12:14 Aug 01, 2024
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Wed, 03 Apr 2024
Several years ago I wrote about
Making
a Land Ownership Overlay with QGIS
and Making
Overlay Maps for OsmAnd.
I've been using that land use overlay for years. But recently
I needed to make several more overlays: land ownership for Utah for a
hiking trip, one for the eclipse, and I wanted to refresh my New Mexico
land ownership overlay since it was several years out of date.
It turns out some things have changed, so here's an update,
starting from the point where your intended overlay is loaded
as a layer in QGIS.
Read more ...
Tags: mapping, GIS, qgis, osmand
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18:15 Apr 03, 2024
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Mon, 27 Nov 2023
The dataset I used for
mapping
fire perimeters
is huge: not surprising if it's all historic fires for the US.
Classifying it in QGIS gave a warning, and operations
were very slow. Here's how to clip a big dataset in QGIS to restrict it
to a smaller geographic area.
Read more ...
Tags: mapping, GIS, qgis, data
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11:43 Nov 27, 2023
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Thu, 23 Nov 2023
(A QGIS beginner's tutorial.)
For quite a while I've been wanting a map showing the perimeters of
the big local fires. When walking through a burned area, I wonder,
was this one from the Cerro Grande fire? Or Las Conchas? Or another fire?
Yesterday, inspired by
Ryan
Peek's #30DayMapChallenge toot on California Fire Perimeters,
I decided to look for the data and load it in QGIS.
Also, I never did an entry for Day 3 of the
#30DayMapChallenge, "Polygons",
so this is it, not quite three weeks late.
Read more ...
Tags: mapping, GIS, fire, Los Alamos, 30 day map challenge
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12:34 Nov 23, 2023
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Mon, 20 Nov 2023
I've been relying more on my phone
for photos I take while hiking, rather than carry a separate camera.
The Pixel 6a takes reasonably good photos, if you can put up with
the wildly excessive processing Google's camera app does whether you
want it or not.
That opens the possibility of GPS tagging photos, so I'd
have a good record of where on the trail each photo was taken.
But as it turns out: no. It seems the GPS coordinates the Pixel's
camera app records in photos is always wrong, by a significant amount.
And, weirdly, this doesn't seem to be something anyone's talking
about on the web ... or am I just using the wrong search terms?
Read more ...
Tags: mapping, GIS, cellphone, google, programming, python, photography, 30 day map challenge
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19:09 Nov 20, 2023
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Thu, 16 Nov 2023
Yesterday's 30-Day Map Challenge
theme was OpenStreetMap.
I use (and contribute to)
OpenStreetMap quite a bit, and I use
OSM basemaps in pretty much all my mapping. (I have used Google in the
past, but between their changing or withdrawing APIs every few years,
and suddenly deciding to
charge
for previously free APIs, I switched to using only open source maps.)
But that was yesterday, which was group hiking day, so I was out
tramping over mountains instead of sitting at the computer making maps.
But a wrong turn on the hike led to a serendipitous discovery that
wouldn't have happened without OpenStreetMap.
Read more ...
Tags: hiking, mapping, pytopo, serendipit, 30 day map challenge
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11:08 Nov 16, 2023
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Sun, 05 Nov 2023
Day 5 of the 30-Day Map Challenge is an analog map.
That got me searching back through old scans, and I found a couple
good ones. In particular, some of my old El Corte de Madera maps.
El Corte de Madera Open Space Preserve is one of the open space parks
in the Bay Area, above Woodside, CA. It's beautiful, dense redwood forest
on a steep hillside. When I lived (and biked) there in the 1990s,
ECdM (as it was abbreviated) was particularly popular with mountain bikers
for its highly technical trails.
Unfortunately, not everybody agreed about those trails. The
Mid-Peninsula Open Space District (MROSD), which administers them,
had a policy that there should never be more than one trail going to
any particular place, and it also had guidelines for trails that
would have eliminated most of the technical ones. The official maps
mostly showed the fire roads, which were especially steep, not at all
technical, and generally not very interesting for biking.
But there were a lot of good trails at ECdM that weren't on the official
MROSD maps. The property had once been used for logging, then for a
while it was owned by a motorcycle (dirt bike) club, so there are all
sorts of unofficial trails.
Mountain bikers passed around many-times-photocopied unofficial maps,
some dating back to the motorcycle club days. One of my treasures
in those days was a much-annotated map, marked up with ink of many colors,
carried so much in my bike bag that it was coming apart at the folds.
Of course, the hand-drawn trails are all approximate: none of us carried
any sort of GPS then, and the GPS of the day probably wouldn't have
gotten a signal in the deep redwood forests anyway.
In 2013 as we were preparing to move to New Mexico, I tried to find
and scan old documents that were prone to getting lost during a move.
I found a couple of old ECdM maps, though I'm not sure I found my main
one; I remember it being more colorful than this one. Still, this one
has a lot of my annotations, so I scanned it in case I lost the paper copy.
Looking at it now brings back a rush memories of mountain biking adventures.
And the map seems perfect for the
30-Day Map Challenge Day 5: Analog Maps.
Day 4: A Bad Map
By the way, although I didn't do any new work for challenge Day 4: A
Bad Map, I wrote an article this past September wherein I go through several
quite bad iterations of a choropleth map (regions shaded according to a
particular variable — in this case a red-blue voting map)
before figuring out how to get the colors right:
Los Alamos Voting Data on a Folium Choropleth Map.
Tags: mapping, 30 day map challenge, MTB, bike
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15:23 Nov 05, 2023
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Sat, 04 Nov 2023
I've been wistfully watching the hashtag
#30DayMapChallenge
on Mastodon. For several years in a row, I've told myself I'm going to try
the 30 Day Map Challenge
... and each time,
I get busy with other stuff. And this year is no different.
So instead of trying to do all thirty exercises, I'll just do a few of
the challenges when I have time and motivation.
Better than nothing, right?
And as it happened, yesterday I got the urge to do a map-related project.
Except it lined up with Day 2, whereas I didn't get it working til
this morning.
So, two days late, here is my:
30 Day Map Challenge Day 2: Lines
During a bike ride along the fast section of one of our fantastic
White Rock trails, I found myself wishing I could view my track logs
colorized according to how fast I was going. And I realized that
I could pretty easily add that to
PyTopo's track log
displaying code. And as long as I was doing that, why not also add
the ability to colorize by elevation as well?
Most GPX track logs already include elevation (though the ones I get
from OsmAnd aren't super accurate:
they're GPS elevation rather than using the barometric sensor that
some phones have). Track logs from OsmAnd sometimes include
speed, via the nonstandard construct
<extensions>
<osmand:speed>0.3</osmand:speed>
</extensions>
which PyTopo already knows how to parse;
and of course, for track logs that don't include speed,
it can be calculated according to the distance
and time difference from the previous track point.
Indeed, it was pretty easy to add. I put it on the context menu as a new
submenu, Colorize Tracks.
I probably should play with the colormaps
and use something smarter than a simple blue-to-red gradient,
but even as it is, it's fun to look at a hike to Nambe Lake colorized
by altitude (first image) or a mountain bike ride along Potrillo Mesa and
the Boundary Trail colorized by speed (second image).
The code is on GitHub, in
this commit.
Again, that's for the challenge two days ago.
Today's Map Challenge is "A Bad Map". No promises that I'll have time for
another mapping project today ... but I'm looking forward to seeing what
other people come up with.
Tags: mapping, GIS, 30 day map challenge, pytopo
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12:28 Nov 04, 2023
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