[HN Gopher] Satellites Spotting Depth
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Satellites Spotting Depth
Author : marklit
Score : 85 points
Date : 2025-05-21 10:12 UTC (2 days ago)
(HTM) web link (tech.marksblogg.com)
(TXT) w3m dump (tech.marksblogg.com)
| qoez wrote:
| There must be some cool application for this but I can't think of
| what. I guess computing shadows and things like that but we often
| already have 3d buildings (though maybe not for rural areas like
| this does).
| gregsadetsky wrote:
| An interesting application of shadow/depth detection is
| estimating the level of oil in those giant circular storage
| tanks..!
|
| https://medium.com/planet-stories/a-beginners-guide-to-calcu...
| mkmk wrote:
| This type of tinkering with data and imagery is so
| satisfying. Wish I had more opportunities to chase stuff like
| this in my life!
| lobochrome wrote:
| Warfare.
| ChrisMarshallNY wrote:
| This is probably the one that will pay the bills.
|
| If you can figure out fairly close-to-the-ground elevations,
| you can model a strike zone quite well.
|
| Good for special operations raids.
|
| But those folks might also have access to specialized NRO
| satellites, that can give you the data without the inference.
| XorNot wrote:
| The US has that but a lot other nations do not, and
| Ukraine's been buying up geospatial imagery all over just
| as fast as it can get it.
| pornel wrote:
| OpenStreetMap often has building outlines, but not building
| height. This would be a nice way to augment that data for
| visualisations (remember: OSM doesn't take auto-generated bot
| updates, so don't submit that to the primary source).
| wkat4242 wrote:
| It does have building height. That's why flightsim 2020 had
| those weird spikes all over the place, people putting "999"
| (or similar) as height on OSM.
| magicalhippo wrote:
| In a few recent bridge collapses and such I've seen they've
| used past satellite data to see how there were signs months or
| years in advanced.
|
| Was also some similar evidence regarding three gorges dam, and
| how it's not doing so great. Ie estimated height of surrounding
| area over time to indicate problematic movement, or something
| like that.
| nebezb wrote:
| Measuring the depth of floods. There's a commercial product
| being sold to insurance companies doing this right now for
| quick and dirty impact assessments.
| Sanzig wrote:
| Interesting, surprised they are using optical data for this
| instead of synthetic aperture radar. SAR (and in particular
| interferometric SAR, although that requires short repeat
| cycle) shines in this area, and a lot of the data is free.
|
| ESA provides worldwide 20m x 5m radar imagery from Sentinel-1
| free online. Revisit in the mid-latitudes is generally a few
| times per week, with an exact repeat cycle every 12 days.
| Once Sentinel-1C is fully operational, it'll be half that.
| thicknavyrain wrote:
| Urban heat island analysis. The physical volumes of buildings
| is an essential input parameter into calculating the estimated
| impact of the built environment and possible interventions
| (e.g. greening, reducing traffic) against local temperature
| rises. It is notoriously difficult to obtain that data at fine
| spatial resolution. This would be a game changer. True to a
| lesser degree for air pollution modelling as well, building
| volume is a significant input for land use regression models.
| cryptonector wrote:
| Flood zone analysis.
| cossatot wrote:
| Similar to the flood analysis others have mentioned, this can
| be used to create databases of buildings with the number of
| stories for each, which is important for understanding how each
| building will respond to various catastrophes (earthquakes,
| strong winds, etc.) in addition to various non-catastrophe
| administrative tasks. The other post about finding the depth of
| oil in oil tanks is actually super interesting to me because
| the amount of oil in the tank is a huge determinant of how it
| will respond to seismic ground motions. I had no idea the top
| sinks with the oil level and am skeptical that it does on all
| of the tanks but it's cool nonetheless.
| Sanzig wrote:
| They pretty much all do by design, it prevents vapours from
| building up at the top of the tank which is a fire/explosion
| hazard.
|
| It works even better with high resolution synthetic aperture
| radar as you can measure the tank height displacement
| directly: https://www.iceye.com/blog/daily-analysis-and-
| forecast-of-gl...
| 7373737373 wrote:
| Trying to find emergency landing spots for planes from any
| position and speed? I'm not sure if planes' computers already
| (continuously) provide this to pilots: "here are the top 5
| landing spots in this and that contingency"
|
| Might be good info to plan safer routes ahead of time too
| Out_of_Characte wrote:
| This wouldn't detect overhead cables, which is the primary
| concern when using this to improve visual landing issues.
| wkat4242 wrote:
| > I'm not sure if planes' computers already (continuously)
| provide this to pilots: "here are the top 5 landing spots in
| this and that contingency"
|
| No they don't. For airliners it doesn't really matter. The
| only place they can set down safely is an airport. Which are
| already listed in their systems and flight plan (alternates)
|
| For the smaller stuff it depends on the pilot, a common
| electronic flight system like the Garmin G1000 doesn't have
| sensors to actually make that determination.
| m463 wrote:
| What about freeways? dry lake beds? the hudson river?
| wkat4242 wrote:
| Yeah but the determination of safety is pretty difficult
| to do and it's extremely rare for this to happen safely.
| Take for example the Gimli Glider. That was an actual
| airport though defunct and from a distance it looked fine
| but in the end it turned out there was a race going on.
| It was only luck that people managed to get out of the
| way in time.
|
| Could an automated system make a better determination
| than a skilled pilot? And is the scenario frequent enough
| to warrant the big cost of cameras etc (keeping in mind
| they must be stabilized and with huge aperture to
| function at night). I doubt it.
|
| The "miracle on the Hudson" was not called a miracle for
| nothing. Usually it ends like a few months ago at
| Washington Reagan.
|
| And a freeway is never a safe place to land an airliner
| of course. The traffic makes it so. Even if there's very
| little, there's lampposts, barriers etc. If an airline
| pilot ever steers towards one they're really going for
| the least terrible option. Small planes fare better of
| course but again they won't have such tech for decades.
| actinium226 wrote:
| I did a similar project as a toy many years ago:
| https://nbelakovski.github.io/topography_neural_net/
|
| In my case I just used it as a vehicle for learning about neural
| networks. I couldn't really think of a compelling use case. I
| wonder if the author of this article of the authors of the model
| have found one.
| jvanderbot wrote:
| Depth from ML was all the rage for a short bit, and I think
| most people filed it under "Things we can do with ML that we
| could already do better other ways". E.g., with a second image.
|
| Certainly it will find a niche use, but during that time the
| headlines in robotics papers were all about replacing
| traditional depth /range sensing with it, which doesn't seem
| plausible.
| chmod775 wrote:
| It's being used a lot to turn regular videos/images into
| stereoscopic VR content. Mostly pornography.
|
| Nunif has tools to convert images/videos or even turn your
| desktop into a stereoscopic image and live-stream it to your
| VR headset over WiFi[1] and there's workflow nodes for
| ComfyUI[2].
|
| I tried the former and it reached conversation speeds of
| around 10FPS for full HD content on consumer hardware, so
| definitely usable. Still, I don't really see the point
| outside adding a gimmick to vacation photos or pornography.
| Don't think anyone would want to convert and consume a non-VR
| hollywood movie this way, but feel free to correct me on
| that.
|
| [1] https://github.com/nagadomi/nunif
|
| [2] https://github.com/kijai/ComfyUI-DepthAnythingV2 +
| https://github.com/MrSamSeen/ComfyUI_SSStereoscope
| wkat4242 wrote:
| There's enough porn in real VR180 format though. There's
| whole platforms for it like sexlikereal. And studios
| specialising in it with famous performers.
|
| Even for that I don't know why you'd want it artificial.
| Porn is all about being as real as possible.
| sandspar wrote:
| Does this mean that Google Earth may get 3D models for more world
| cities? As of today they only have 3D for a limited number of
| cities, mostly from wealthy countries. Also, would Microsoft
| Flight Simulator also get more accurate 3D cities? And what about
| terrain? Google Earth uses mostly guesses to gauge the height of
| rural terrain like mountains.
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