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Photogrammetry on commercial flights (2021)

leifgehrmann.com

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Re: Photogrammetry on commercial flights (2021)

#31

Post by arthur2e5 »

dale_glass wrote: post #25
Toutouxc wrote: post #8

> 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 a…

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…

It's mostly the direction: you don't get a lot of vertical acceleration on land except on a bumpy road or a amusement part. Slight loss of gravity takes some getting used to.

Re: Photogrammetry on commercial flights (2021)

#32

Post by quickthrower2 »

Toutouxc wrote: post #8

> 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 a…

Pilots can have the opposite problem: a plane smoothly banking at night can feel like nothing at all. So they have to trust their instruments not their inner ear.

Re: Photogrammetry on commercial flights (2021)

#33

Post by quickthrower2 »

scyzoryk_xyz wrote: post #27
JoeAltmaier wrote: post #24

Earlier quoted context omitted.

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.

law !== enforcement

thus why “nothing to hide” applies to very few people as most people could be taken to court for something and by judge or jury punished for that thing. Let alone sued.

Re: Photogrammetry on commercial flights (2021)

#34

Post by wcrossbow »

prashp wrote: post #5

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?

A big part of my day job is to develop an image processing pipeline for a satellite constellation.

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.

Re: Photogrammetry on commercial flights (2021)

#35

Post by wcrossbow »

He quotes that you need a lot of points and a fancy transformation to correct images while taking into consideration the differences in elevation within the scene. While it is true that having more points is important, the better way is to actually also consider the elevation of the identified points using a digital elevation model (DEM). That increases the accuracy of the transformation a lot and reduces the number of points needed. The idea is that you build a transformation from R^3 -> R^2 instead of just R^2 -> R^2, usually a rational polynomial function.

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

Re: Photogrammetry on commercial flights (2021)

#36

Post by Toutouxc »

vhcr wrote: post #11
Toutouxc wrote: post #8

> 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 a…

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?

Yeah, absolutely. Any VR game that moves the camera (me) without me commanding it is torture. Like, I bump the stick by accident, the character takes two steps forward and I immediately feel a tug in my stomach and a wave of dizziness and panic.

Re: Photogrammetry on commercial flights (2021)

#37

Post by Toutouxc »

dale_glass wrote: post #25
Toutouxc wrote: post #8

> 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 a…

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…

> 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).

Re: Photogrammetry on commercial flights (2021)

#38

Post by fxtentacle »

atourgates wrote: post #14

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://openaerialma…

I tried to run the numbers on a similar idea some years back and our conclusion was that the processing power needed to do the photogrammetry ends up being more expensive than just renting long-term read access to the downlink from a high-resolution satellite.

Re: Photogrammetry on commercial flights (2021)

#39

Post by pwillia7 »

fsloth wrote: post #10

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

wow - that's pretty good

Re: Photogrammetry on commercial flights (2021)

#40

Post by MrLeap »

wcrossbow wrote: post #35

He quotes that you need a lot of points and a fancy transformation to correct images while taking into consideration the differences in elevation within the scene. While it is true that having more points is important, the better way is to actually also consider the elevation of the identified points using a digital elevation model (DEM). That increases the accuracy of the transformation a lot and reduces the number…

Ahhh your blog post was precisely what I needed a few years ago. Maybe it'll come up again :)
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