Developing A "Hot Spot" Map

Hello All,

Some local club members are really getting into logging their flights
and posting them on the OLC. One posed a good question about trying
to use the flight tracks to develop a better sense of the best soaring
spots in the area by viewing multiple flight tracks at a time. I'm a
computer-geek by trade and this naturally got my brain thinking about
potential programmatic solutions. I'm TOTALLY swamped with work and
club-officer duties (that I'm behind on), but I thought I'd toss this
out if anyone wants to take it up as a project:

I'm envisioning something like a Google Maps overlay that has color-
coded points or blobs based on the average vario reading or climb-rate
in a given area. Obviously you would need a certain number of
overlapping or nearby data-points to generate a decent average.

Here's one potential implementation strategy: You have an "offline"
processing program that takes a bunch of IGC files and scrutinizes all
of the datapoints that they contain within a predefined geographic
area (a set of lat/long coordinates as a bounding-box or something).
This bounding-box could be broken down into sectors that are
equidistant to any adjacent sector (imagine a grid, with the center-
point of each grid square being 150m or ~500 feet from the center-
point of each adjacent square). The processing program could iterate
through each sector, looking at all of the IGC data-points that fall
within the current one. As long as a certain minimum threshold of
points could be found, a reasonable average value could be
calculated. To make the average value more universal with regards to
actual airmass movement, you'd need to know the speed and type of
glider that is responsible for each data-point, and remove its
theoretical sink-rate at that speed (wingloading is perhaps another
required variable - though a smart program with a baseline polar for
that glider should be able to make a good guess about the wingloading
if it looks at a variety of sink-rates and speeds over the course of
the glider's IGC log). You'll get a little error because inevitably
each glider's performance will deviate slightly from the theoretical
sink-rate at its recorded speed, and the contributor might have been
maneuvering in an unusual manner at a certain spot; but over a large
enough set of flights it would be a small error.

These average values for each sector could then be written into a
database and used as the source value for the Map overlay/display.
Over time, the processing program could be re-run periodically with a
new (larger) set of ICG files, resulting in more datapoints being
evaluated.

Anyone think this is interesting enough to give it a whirl?

Take care,

--Noel
P.S. I have already thought about mixed lift sources overlapping and
causing "misinterpretation" of the data, as well as the fact that some
areas will always be overflown by pilots in a certain manner (while
never looking for lift even if its there)... I don't view these as
bad things - they might not result in a map that accurately shows
climb-rates to expect, but the overall map would result in a sort of
"betting guide" to the more likely spots of useable or useful lift in
the area, based on terrain, lift, and other pilot's experiences...

Hi,

I'm envisioning something like a Google Maps overlay that has color-
coded points or blobs based on the average vario reading or climb-rate
in a given area. Obviously you would need a certain number of
overlapping or nearby data-points to generate a decent average.

Akaflieg Frankfurt have done something similar. See:

http://www.akaflieg-frankfurt.de/ind...t/LIFT-Projekt

for a paper describing the project (sorry, german only) and

http://www.akaflieg-frankfurt.de/ind...t/Thermikkarte

for the actual implementation.

Ciao, MM
--
Marian Aldenhövel, Rosenhain 23, 53123 Bonn
http://www.marian-aldenhoevel.de
"Success is the happy feeling you get between the time you
do something and the time you tell a woman what you did."

On Tue, 08 Jul 2008 20:50:48 -0700, noel.wade wrote:

I'm envisioning something like a Google Maps overlay that has color-
coded points or blobs based on the average vario reading or climb-rate
in a given area. Obviously you would need a certain number of
overlapping or nearby data-points to generate a decent average.

Don't forget that time of day (and of year?) is likely to be important.
The simplest approach might be to simply break each trace into separate
points, each interpolated between successive GPS fixes and indexed by
- location,
- date&time,
- altitude(?)

The value at the point would be the vertical rate calculated from time
interval and altitude difference, possibly adjusted as you suggest for
flying speed and glider polar.

When you have enough data it should be possible to see if there's any
usable signal amongst the noise.


--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot

I've seen evidence that people have done this. Some of the user
sceneries for Condor mention having
analyzed igc files to generate the thermal probability chart.

A good first pass would just determine overall climb rates per
thermal. Examine the time spent with a
ground speed below about 60kts (100kph), and average out the climb
rate. That makes one data point,
which can be assigned a grid address. The grid could be determined on
one minute (lat/long) intervals,
or better yet on 0.02 degree intervals (since igc files list locations
in ddd.dddd format). The data could
be summarized in a google overlay, with the color indicating lift
strength and the saturation the number
of data points.

Sounds like fun! (said the true computer geek)

-- Matt

On Jul 8, 11:50 pm, "noel.wade" wrote:
Hello All,

Some local club members are really getting into logging their flights
and posting them on the OLC. One posed a good question about trying
to use the flight tracks to develop a better sense of the best soaring
spots in the area by viewing multiple flight tracks at a time. I'm a
computer-geek by trade and this naturally got my brain thinking about
potential programmatic solutions. I'm TOTALLY swamped with work and
club-officer duties (that I'm behind on), but I thought I'd toss this
out if anyone wants to take it up as a project:

I'm envisioning something like a Google Maps overlay that has color-
coded points or blobs based on the average vario reading or climb-rate
in a given area. Obviously you would need a certain number of
overlapping or nearby data-points to generate a decent average.

Here's one potential implementation strategy: You have an "offline"
processing program that takes a bunch of IGC files and scrutinizes all
of the datapoints that they contain within a predefined geographic
area (a set of lat/long coordinates as a bounding-box or something).
This bounding-box could be broken down into sectors that are
equidistant to any adjacent sector (imagine a grid, with the center-
point of each grid square being 150m or ~500 feet from the center-
point of each adjacent square). The processing program could iterate
through each sector, looking at all of the IGC data-points that fall
within the current one. As long as a certain minimum threshold of
points could be found, a reasonable average value could be
calculated. To make the average value more universal with regards to
actual airmass movement, you'd need to know the speed and type of
glider that is responsible for each data-point, and remove its
theoretical sink-rate at that speed (wingloading is perhaps another
required variable - though a smart program with a baseline polar for
that glider should be able to make a good guess about the wingloading
if it looks at a variety of sink-rates and speeds over the course of
the glider's IGC log). You'll get a little error because inevitably
each glider's performance will deviate slightly from the theoretical
sink-rate at its recorded speed, and the contributor might have been
maneuvering in an unusual manner at a certain spot; but over a large
enough set of flights it would be a small error.

These average values for each sector could then be written into a
database and used as the source value for the Map overlay/display.
Over time, the processing program could be re-run periodically with a
new (larger) set of ICG files, resulting in more datapoints being
evaluated.

Anyone think this is interesting enough to give it a whirl?

Take care,

--Noel
P.S. I have already thought about mixed lift sources overlapping and
causing "misinterpretation" of the data, as well as the fact that some
areas will always be overflown by pilots in a certain manner (while
never looking for lift even if its there)... I don't view these as
bad things - they might not result in a map that accurately shows
climb-rates to expect, but the overall map would result in a sort of
"betting guide" to the more likely spots of useable or useful lift in
the area, based on terrain, lift, and other pilot's experiences...

WinPilot does this -- the Thermal Database feature.

Much more important than glider polars are the wind conditions and sun
positions, for determining the thermal source on the ground (which can
be miles away from the lift) and when it's working.

~ted/2NO

An entirely different but interesting approach:

After this lecture Beda Sigrist, also from Switzerland presented his
paper “Use of topographic radar scans to identify thermal hotspots in
Alpine areas”.Thermals are part of the atmospheric energy flow caused
by solar irradiation. The question behind this project, called
TherMap, has been if variations of the solar irradiance, caused by the
local topography, could be a useful predictor of thermals. Using high
resolution digital data of the topography the local irradiance was
therefore computed. The results, considering the different radiation
angles were displayed on maps, leading to first plausible results for
the morning hours of mountain areas. In a second step these models
were refined to consider the thermal inertia of the soil and the air,
the different vegetation factors, as well as the reflection of snow
surfaces. For Alpine areas the resulting maps turned out to show a
high level of agreement with superimposed flight tracks. For
topographically less significant areas, like the Jura, the results
were not so good. No conclusive results could be obtained for
topologically still smoother landscapes, where other factors are
likely to be predominant.

from

http://www.wgc2006.se/sub/firstpage.php?Id=67


Dan

noel.wade wrote:


Anyone think this is interesting enough to give it a whirl?

I think it's quite interesting and worth pursuing. Winpilots
implementation seems like a good approach, but I not heard anyone
discuss it's worth, and I've seen only the most limited of comments on ras.

Here are some links from people that have pursued this idea in the past.
They seem to be current:

http://www.diff.net/peter/thinking/thermalfinder/


http://www.friulano.it/t2t_eng.htm


http://soaringtools.com/

http://www.pfg.dk/termikanalyse/

A serach for "thermal finder", etc, might yield a few more sites.

--
Eric Greenwell - Washington State, USA
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