Photogrammetry on commercial flights (2021)
leifgehrmann.com
leifgehrmann.com
If anybody is interested the word to search for is orthorectification.
Shameless plug. I recently published a post on my blog on how to calculate a projective transformation for an image if you know a few parameters of your camera (focal length and sensor size) and its position and orientation. My use case is satellite imagery so this is always available http://maxwellrules.com/math/looking_through_a_pinhole.html
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.
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
One barrier for OAM seems to be that it requires the image to be already orthorectified. To be more like Mapillary you'd need a service that takes georefed pictures and does its own processing.
In the case of airplane window photos where georef is not going to be good enough, you might need existing photos to correlate with -- ADS-B track combined with time can help provide a starting guess, but not much else.
https://en.wikipedia.org/wiki/Stereo_photography_techniques#...
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.
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.
To me it feels like sitting in a chair that’s hurtling forward at 900 km/h and randomly rising and falling by a few meters. I’m not forgetting that for a second. It’s not that uncomfortable at cruise altitude, but I’m definitely very aware of what’s happening and how even tiny changes in pitch are tied to quite large and long acting G forces (compared to sitting in a chair, not to a rollercoaster).
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!
OpenDroneMap can do that for example.
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.
Using SIFT or another keypoint detector is one of the ways to do georeferecing. You take a basemap and your image and match keypoints on both then calculate your transformation. There are a few things that make the problem harder than just use SIFT but it is a good starting point.
Still disappointed that good free map sources are all flat, from what I can tell.
I've been wondering for some time, how far do national laws about data sharing matter any more?
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.
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...
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).
/s