[HN Gopher] Photogrammetry on Commercial Flights (2021)
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Photogrammetry on Commercial Flights (2021)
Author : tildef
Score : 110 points
Date : 2023-08-30 17:25 UTC (5 hours ago)
(HTM) web link (leifgehrmann.com)
(TXT) w3m dump (leifgehrmann.com)
| sorenjan wrote:
| Check the laws in your country before doing this, in Sweden you
| need permission to distribute aerial photos.
| JoeAltmaier wrote:
| The internet makes that problematical. Does 'distribution'
| include 'share on facebook'?
|
| I've been wondering for some time, how far do national laws
| about data sharing matter any more?
| sorenjan wrote:
| Yes, any distribution including online. Personally I think
| it's a bit anachronistic to ban distribution of photos now
| when it's so easy to take and distribute them, not to mention
| all kinds of commercial services with free aerial and street
| view photos. People do get prosecuted for it still, so it
| very much matters.
|
| https://www.lantmateriet.se/en/dissemination-permit/
| JoeAltmaier wrote:
| I share such photos, and never got arrested. But I'm not
| Swedish.
|
| If you're Swedish and share such photos in the US, is it a
| crime?
|
| Where is the 'internet' at? Certainly not in any particular
| nation.
|
| Thus my confusion.
| Toutouxc wrote:
| > But other than taking a few photos of holiday mementos and
| lens-flaring sunsets, what's the point?
|
| OT, but for me the point is not having my body absolutely panic
| from experiencing all kinds of rotation and sudden lateral
| displacement without anything happening visually. Honestly, I
| have no idea how people fly anywhere else, I wouldn't be able to.
| The speeds and forces experienced even on a calm commercial
| flight are, as far as human evolution goes, total nonsense.
| vhcr wrote:
| Same way I have no idea how people get dizzy so easily, do you
| get dizzy when on a boat, or when using a VR headset?
| dale_glass wrote:
| What you experience on a regular flight is a complete non-issue
| compared to what you can experience in a car, in an amusement
| park, or in VR.
|
| And if you remove the direct comparisons, then people do things
| like say, war, parachute jumping, or underwater welding that
| are way more extreme.
|
| Really like everything it's just the matter of getting used to
| it. As a kid flying used to be amazingly exciting. Then I got a
| job that involved flying twice a week and it very quickly got
| routine.
|
| The weird forces also don't last very long at all. For the vast
| majority of the flight is just sitting in a chair, and feels
| exactly like that.
| crazygringo wrote:
| This is not photogrammetry as the word is usually understood
| these days.
|
| Photogrammetry usually means constructing a 3D model out of a
| number of 2D photos from lots of different angles, although there
| are broader definitions as well [1].
|
| This is just skewing a photo you took out the window to overlay
| it on a map.
|
| From the title, I was expecting this to be something about
| constant super-hi-res photography attached to commercial flights
| that would actually let you build 3D models of the landscape...
|
| [1] https://en.wikipedia.org/wiki/Photogrammetry
| maxbond wrote:
| I think that's probably a function of the context you're
| encountering photogrammetry in, it's literal meaning (as
| described in the Wikipedia article) is "measuring stuff from
| photos." I believe what you're describing is generally referred
| to as "3D reconstruction."
|
| For what it's worth, this article was pretty much exactly what
| I anticipated it to be. But language is funky, and obviously
| other people shared your expectation (which makes it a good
| comment in my view).
| tshaddox wrote:
| Even in 3D rendering for animation, video games, archviz,
| etc. I often hear photogrammetry discussed in the context of
| making reusable textures, not just making specific 3D models.
| M3L0NM4N wrote:
| That's what I was expecting as well. Still a cool project
| nonetheless.
| [deleted]
| 1-6 wrote:
| Correct, the technique is called orthorectification.
| groggo wrote:
| You can also do this to create stereo photography!
|
| https://en.wikipedia.org/wiki/Stereo_photography_techniques#...
| cscheid wrote:
| Indeed you can! http://cscheid.net/static/clouds/
| fsloth wrote:
| To explain the underwhelmed response I guess most people were
| expecting 'google maps quality' 3d models. Which is not an
| unreasonable expectation, given an aerial platform such as a
| drone converting photos to 3d models of large areas is
| commoditized. Just dump photos to an application such as Agisoft
| Metashape or Luma, wait a bit and you can get something like this
| for example: https://skfb.ly/6DvVP
| prashp wrote:
| This is very cool! How feasible would it be to take a video
| instead of a photo, then using landmark detection and a stitching
| algorithm such as SIFT to cover a larger surveying area?
| klysm wrote:
| That would be more like photogrammetry
| spookie wrote:
| You can think of a video as a set of images taken from the same
| camera from different perspectives. So, you can assume as if
| they're different cameras (with the added bonus that the camera
| intrisincs remain the same), and apply "multi camera"
| techniques. I'm assuming you "move" the camera for parallax and
| what not.
|
| With this, you can retrieve depth information by correlating
| the difference in position of easily identifiable points, and
| recreate the scene as a mesh.
|
| This is basically the basis of photogrammetry as I know it. AI
| solutions may help at various stages to speed up the process
| too.
| sorenjan wrote:
| A better solution would be to use a program that does what most
| people think of when they hear the word photogrammetry these
| days, 3D reconstruction from multiple images, and then make an
| orthorectified image from that.
|
| OpenDroneMap can do that for example.
|
| https://www.opendronemap.org/webodm/
| 1-6 wrote:
| An areal photo that's orthrorectified with ground images as a
| secondary source would provide better normals. Of course we'd
| also use differential GNSS base-point targets to stitch the
| images together. It's difficult to get consistent color
| temps, exposure, etc with multiple ground images shot at
| various times throughout the day.
| cscheid wrote:
| I didn't use sift, but instead a very dumb old trick of slit
| screen photo: http://cscheid.net/static/windowseat/
|
| This is 5h of a single video from EWR to SFO by a former
| colleague. Turns out even a dumb trick like this still is
| enough to pick out a bunch of geographical features!
| atourgates wrote:
| Despite the author's criticisms, it seems like there's lots of
| opportunity for UAV-generated open source imagery, but I can't
| really find an active community for sharing it.
|
| Open Aerial Mapp[1] seems like a good start, but doesn't seem to
| be particularly active.
|
| Seems like we could use a "Mapillary[2] but from Above" type of
| project - only one that doesn't end up getting acquired by
| Facebook.
|
| [1] https://openaerialmap.org/
|
| [2] https://www.mapillary.com/
| ajsnigrutin wrote:
| https://github.com/OpenDroneMap/ODM
|
| You take a drone, point the camera mostly down (a narrow angle,
| not straight down), take photos of land, with some overlap,
| preferably from different angles, load the software, and it
| creates an ortophoto, 3d model, height map, all georeferenced
| jrh3 wrote:
| Seems much easier than when I had to do this manually onto Google
| Earth.
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