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Earth rotation limits in-body image stabilization to 6.3 stops (2020)

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Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#31

Post by TaylorAlexander »

crubier wrote: post #27
t0mas88 wrote: post #21

You don't need GPS to figure out the correction for this. Inertial navigation systems in aircraft (which use very stabilised platforms with a lot of math involved) worked before GPS was available. It helps to have a rough indication of the current latitude on startup, but you can also figure it out from the gyro outputs. Just takes longer. With modern sensors (solid state laser gyroscopes) it has all become a lot sma…

Aerospace grade laser gyroscopes are incredibly expensive (and bulky), and even then, they still have massive drift after several hours. If you don't have GPS to relocalize precisely at least every day, there is no way you can know the location of the camera on earth for more than a day, even with state of the art aerospace stuff

Realistically GPS is the answer, but it’s notable that you could also use a simple light sensor combined with accurate clocks to get your position on earth:

https://en.m.wikipedia.org/wiki/Light_level_geolocator

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#32

Post by sokoloff »

Asraelite wrote: post #30

> The first isn’t a good solution for many reasons. Don’t have GPS signal? Shooting next to a magnet? Your system won’t work. These seem trivial to work around. Just store the last known position and use that. It's rare that you'll be without a GPS signal or beside a magnet, and you certainly won't be traveling long distances in those conditions. And since when do magnets block GPS signals?

It’s not that a magnet blocks GPS signals, but it does affect the compass in the context of using 6 of the 9 degrees of freedom in the first proposed solution: “Use the camera’s GPS, accelerometer, and compass to calculate exactly where it is pointed and its latitude. ” (This solution should also do sensor fusion with the gyroscope, not just accelerometer and compass for orientation from a 9DoF system.)

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#33

Post by vmfunction »

TaylorAlexander wrote: post #31
crubier wrote: post #27

Earlier quoted context omitted.

Aerospace grade laser gyroscopes are incredibly expensive (and bulky), and even then, they still have massive drift after several hours. If you don't have GPS to relocalize precisely at least every day, there is no way you can know the location of the camera on earth for more than a day, even with state of the art aerospace stuff

Realistically GPS is the answer, but it’s notable that you could also use a simple light sensor combined with accurate clocks to get your position on earth: https://en.m.wikipedia.org/wiki/Light_level_geolocator

> Recording light levels over time Wonder how much time is needed to determine location.

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#34

Post by throw0101c »

t0mas88 wrote: post #21

You don't need GPS to figure out the correction for this. Inertial navigation systems in aircraft (which use very stabilised platforms with a lot of math involved) worked before GPS was available. It helps to have a rough indication of the current latitude on startup, but you can also figure it out from the gyro outputs. Just takes longer. With modern sensors (solid state laser gyroscopes) it has all become a lot sma…

> You don't need GPS to figure out the correction for this.

Perhaps not, but a lot of cameras already have it for geotagging purposes (EXIF), so why not use it:

* https://en.wikipedia.org/wiki/List_of_cameras_which_provide_...

* https://www.digitalcameraworld.com/buying-guides/best-camera...

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#35

Post by Rinzler89 »

t0mas88 wrote: post #21

You don't need GPS to figure out the correction for this. Inertial navigation systems in aircraft (which use very stabilised platforms with a lot of math involved) worked before GPS was available. It helps to have a rough indication of the current latitude on startup, but you can also figure it out from the gyro outputs. Just takes longer. With modern sensors (solid state laser gyroscopes) it has all become a lot sma…

> Inertial navigation systems in aircraft (which use very stabilised platforms with a lot of math involved) worked before GPS was available.

Inertial measurement units for aircrafts and submarines cost as much as a house in California. Good luck putting those in a phone.

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#37

Post by TaylorAlexander »

vmfunction wrote: post #33
TaylorAlexander wrote: post #31

Earlier quoted context omitted.

Realistically GPS is the answer, but it’s notable that you could also use a simple light sensor combined with accurate clocks to get your position on earth: https://en.m.wikipedia.org/wiki/Light_level_geolocator

> Recording light levels over time Wonder how much time is needed to determine location.

You just need to determine the time of sunrise and sunset relative to a known location and you get a rough idea of latitude and longitude.

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#38

Post by siriaan »

nimbleal wrote: post #18
kqr wrote: post #2

6.3 stops is a lot, though. That's basically the fully usable aperture range of a kit zoom lens.

Yes, or considered another way 1/25th shutter vs almost 1/2000th, ie a lot of motion blur vs. virtually nothing will be able to provoke blurring

Except a moving subject, of course.

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#39

Post by ben_w »

Rinzler89 wrote: post #35
t0mas88 wrote: post #21

You don't need GPS to figure out the correction for this. Inertial navigation systems in aircraft (which use very stabilised platforms with a lot of math involved) worked before GPS was available. It helps to have a rough indication of the current latitude on startup, but you can also figure it out from the gyro outputs. Just takes longer. With modern sensors (solid state laser gyroscopes) it has all become a lot sma…

> Inertial navigation systems in aircraft (which use very stabilised platforms with a lot of math involved) worked before GPS was available. Inertial measurement units for aircrafts and submarines cost as much as a house in California. Good luck putting those in a phone.

The IMUs that existed on aircraft before the invention of GPS have been superseded by the ones which actually are in your phone, in much the same way and for much the same reason that a $20 Casio F-91w keeps better time than a fancy Rolex that costs more than a house in California: electronics are cheaper and better than mechanical systems.

We have, naturally, also made better IMUs for places where it matters, ones which won't fit in your phone.

The question is therefore not suited to "aircraft grade, yes or no?", it's "how expensive is the cheapest IMU that's good enough for the specific need?" which in this case itself depends on how many stops is desired.

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