Clutter data in the public domain is mostly 30 meter square
resolution. Cameron has talked about a lot of the issues with the
data. Radio Mobile (and TowerCoverage since it runs on that) has the
ability to tune the cluster classifications a bit. I worked with Roger
in implementing that clutter model. It is not actually part of the
Longley Rice propagation model, what he did at my begging was allow a
user to manually edit the height and density for each clutter class
and then the tool assigns a loss factor per pixel/30 meter square of
clutter and then subtracts the sum total of the clutter loss for the
ray being propagated. This is not perfect but when the cell companies
use their expensive propagation tools, they tune their clutter models
for each market by drive testing a known transmitter with a roving
unit and run those drive test results against what the software thinks
the signals should be. In this process they compare the know clutter
classes that were propagated through and it self-tweaks the loss
factors is applies for each clutter class. In radio mobile you do
basically the same thing but without automation. To get it right you
have to go out and measure a lot of your real world signal levels and
manually run propagations until the two match (minus your fade margins
built in to your plots).
This works well if you spend the time, the bigger issue is that the 30
meter square is assigned just one clutter class code. In general it
works well for free stuff. The reality of knowing about specific tree
lines alongside a house or in urban environments with tree lined
streets or in back years, those individual trees to not get factored
in to your propagation, just the building losses if that building
clutter is set to a height to show as an obstruction(in WISP cases
most are not if you are mounting your antenna on the roof for average
suburban clutter). The answer to this is to have higher resolution
clutter. The terrain data used is 10 meter resolution, meaning there
have been hard data points gathered at least every 10 meters
horizontally and interpolated. Some terrain data is available at 3
meters but that is not as widely available. So the issue remains how
do you get better resolution clutter data. LIDAR can indeed be used
and the best versions are actually driven on the streets and not flown
from the air. As Cameron mentioned however that data still only gives
you the height/size/area where the clutter is. It does not tell you
what type of class that it is and/or what type of RF losses each pixel
of that data should be assigned, plus you are typically only getting
the clutter data from the street facing side. Think of the old movie
sets and only seeing the building face.
Another method of increasing clutter accuracy is to resample the data
from 30 meter pixels down to smaller sized pixels. This has limited
benefit. Mostly this can allow you to take things like tree clutter
and trim out the highway areas and or possibly cut out the trees with
specific building data footprints and assign a different clutter class
by pixel. This is very tedious to do on a large scale and you first
have to have other good data sources to trim or reclassify these
smaller pixels properly to a new clutter class. While all of this
gives you a better physical map of what and where you have clutter
down to a more realistic reality, you would then have to go back and
manually recalibrate the tuning because tuning over larger pixels is
an averaging process using the single clutter class. As you might
guess all of this takes time and money. At some point there will
likely be some cool efforts done by others where we can integrate
this. For instance Microsoft released building outline GIS data for
the whole country that they machine learned from aerial imagery. That
could be used over resampled data although if the buildings had tree
cover they didn’t get captured in the first place because they are not
visible in the images. There are other open source projects for things
like spectrum sensing on a Raspberry Pi and software defined radio
that if you put enough sensors out there they might help tune the
clutter loss models. https://electrosense.org/
This is probably way more than you wanted to read about clutter data
and RF propagations but hey I am a geek like that.
Thank You,
Brian Webster
www.wirelessmapping.com <http://www.wirelessmapping.com>
www.Broadband-Mapping.com
*From:*AF [mailto:af-boun...@af.afmug.com] *On Behalf Of *castarritt .
*Sent:* Thursday, December 05, 2019 4:47 PM
*To:* AnimalFarm Microwave Users Group
*Subject:* Re: [AFMUG] clutter data and drones
Google maps uses some of the 1M resolution LIDAR data. Check out
Austin, TX (maybe most other metro areas as well?) in google, enable
"globe view", and then turn on 3D. Now use left ctrl and drag with
the mouse to move your view angle. This is the data cnHeat and the
Google CBRS SAS solution supposedly use. OT: I wonder if any of the
usual suspects are making PC flight simulators that use this data.
On Thu, Dec 5, 2019 at 3:30 PM Steve Jones <thatoneguyst...@gmail.com
<mailto:thatoneguyst...@gmail.com>> wrote:
The issue with publicly available clutter data is it seems old,
poor resolution or inaccurate. If heat is using the same data as
linkplanner, its definitely bunk.
On Thu, Dec 5, 2019 at 3:26 PM Adam Moffett <dmmoff...@gmail.com
<mailto:dmmoff...@gmail.com>> wrote:
Have you looked at CnHeat?
We're about to do some testing with it here. They mentioned
USGS LIDAR as one of the data sources. Presumably that's
blended with other imaging somehow.
On 12/5/2019 4:02 PM, Cameron Crum wrote:
LIDAR is not clutter specific, it just can't penetrate
clutter (it's light) so clutter ends up looking like
terrain. The benefit is that you get an elevation, the
drawback is that you don't know the type of clutter or how
high it is above the terrain. I suppose if you compare the
lidar data against a terrain only DEM, you could extract
the clutter height. Here is the thing... some propagation
does penetrate vegetation to some degree, so if you are
talking about frequencies that do, then lidar is not
necessarily a good thing to use as everything ends up
looking like an obstruction. You also need a model that
can actually account for clutter (vegetation) density when
talking about how much it will affect the signal.
Obviously leaf types and things like that can have other
effects, but I'm unaware of any model that goes to that
depth. While some account for clutter heights to use
diffraction losses and some lump-sum type losses for a
given clutter category, none of the models that are in use
in the wisp industry account for clutter density and there
are only a few in existence that do.
You can get high res clutter data (types) from thermal
satellite imaging from one of the geospatial data
companies like Terrapin Geographic, or SPOT. It is
surprisingly accurate and is what real prop tools like
Planet use. The downside is no elevations, so you still
have user input for that. Unless you are willing to shell
out big bucks, don't bother looking. We are talking about
10's of thousands for a modestly sized area. The cellcos
can afford it.
On Thu, Dec 5, 2019 at 10:41 AM Adam Moffett
<dmmoff...@gmail.com <mailto:dmmoff...@gmail.com>> wrote:
Interesting. And unfortunately I don't know any more
about LIDAR than a Google Search does.
On 12/5/2019 11:27 AM, Steve Jones wrote:
Just the SAS administrators will be
competitive product. So garbage in garbage out
will really apply. Basic SAS functionality is
uniform, but feature sets will differ. More
accurate propagation modeling every night will be
something we benefit from and Im thinking that
will be one of the things they compete against
each other with. They didnt say that specifically,
but the second iteration of SAS will be more
bigger, potentially even bigly in its scope. I
really thought it was all going to be modeled
after cellco, with a bend toward cellcos
overtaking CBRS with shady handshakes and
involuntary roaming agreements, but it appears
winnforum isnt just government lackeys, the people
involved have actually put gear in the air or at
least listen to those that have. I think
cantgetright may have been a co-chair of a
committee somewhere
Where would a guy who doesnt know what LIDAR is go
to find out more about that clutter data?
On Thu, Dec 5, 2019 at 10:12 AM Adam Moffett
<dmmoff...@gmail.com <mailto:dmmoff...@gmail.com>>
wrote:
I think the USGS is making 3D clutter maps
with LIDAR. CnHeat is supposed to use that
wherever it's available.
I haven't heard how that relates to the SAS
though. Is this something you learned from
the "450 Lady"? Care to share?
On 12/5/2019 10:25 AM, Steve Jones wrote:
first question is if a guy collects
accurate clutter data, can he use it in
any of the propagation tools we use?
second, and this is where you braniacs
come in, what equipment would it take on a
drone to collect this data?
IIRC drone limit without FAA is something
like 300 feet. would that even be tall
enough to sweep a wide enough path that it
wouldnt take 300 battery charges to do a
square mile?
I envision a course plotted drone trip
that will fly over with a pilot car
trailing to maintain the required operator
LOS.
If you think about how many miles youve
put on verifying link paths over the
years, its not really a prohibitive thing.
CBRS and SAS is whats driving this query,
but general propagation anomalies creates
quite a pickle that better
accuracy/resolution clutter accuracy would
alleviate.
Please tell me there is already a
consortium thats built out a clutter
standard with a clutter submission
mechanism, that would completely tickle me
silly.
I also dont know the impact to the
propagation back ends as you increase the
resolution of the data. Im assuming the
SAS administrators are running something a
little beefier than Radio Mobile.
I could see this being a lucrative niche
market, if there were a way around the
drone operator licensing requirements
(though that cost is pretty minimal).
Basically a company builds up a small
fleet of drones, outfitted with the
appropriate gear. You create an account,
input your coverage area (or any region)
that you want high resolution data for.
they reprogram the course and ship it to
you (after collecting the upfront payment,
deposit, and massive liability release)
they provide you with a road course to
drive while the drone does its thing,
anticipate points of retrieval for
recharge, etc. when its all done, you
stick it in the box and ship it back.
would be cooler if the whole thing was
transported back and forth by amazon drones.
If I had a guarantee that the collected
data would be useful to the company, into
radio mobile, link planner, towercoverage,
and SAS administrators, its something i
could see a fair price tag of 3-10k on it
for our coverage area, and no farmers
blasted it out of the sky.
we use clutter data now thats antiquated
so it would come with the understanding
that photosynthesis and bulldozers impact
accuracy from the minute its collected.
maybe this data is already out there and i
dont know?
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