Forum

Author Topic: image stabilisation - yes or no  (Read 2714 times)

JJ

  • Newbie
  • *
  • Posts: 24
    • View Profile
image stabilisation - yes or no
« on: June 07, 2021, 05:54:46 PM »
seems to be a lot of conflicting information on this with some saying it's a big no no, and others saying it's a must have.

is there an official view on this?

i'll be scanning a garden this week using a painters pole to get some height.  Should I use IS?

Olympus (micro 4/3) system with FE lens

wojtek

  • Full Member
  • ***
  • Posts: 240
    • View Profile
Re: image stabilisation - yes or no
« Reply #1 on: June 07, 2021, 08:18:26 PM »
Yeah if it's not on a tripod there is no reason to not use IS.

JJ

  • Newbie
  • *
  • Posts: 24
    • View Profile
Re: image stabilisation - yes or no
« Reply #2 on: June 07, 2021, 11:05:58 PM »
thanks for confirming

JMR

  • Sr. Member
  • ****
  • Posts: 439
    • View Profile
Re: image stabilisation - yes or no
« Reply #3 on: June 11, 2021, 03:15:46 AM »
I'm open to learn, but to my understanding, IS means lots of changing conditions in calibration parameters between shots. This is mainly in terms of principal point, but also, with modern 5 axis IBIS, I guess also more parameters are involved. Do you, Wojtek, mean this is nothing one should be worried about at all
Or... is there something to be added to your "why not IS?" like "however, you would need to un-group cameras in calibration". Thanks

cbnewham

  • Full Member
  • ***
  • Posts: 115
    • View Profile
Re: image stabilisation - yes or no
« Reply #4 on: June 11, 2021, 10:45:32 AM »
Yeah if it's not on a tripod there is no reason to not use IS.

IS shifts the image. I would have thought this would be detrimental because the parameters of the lens would change shot to shot.

3create

  • Newbie
  • *
  • Posts: 11
    • View Profile
    • 3create
Re: image stabilisation - yes or no
« Reply #5 on: June 15, 2021, 11:03:58 PM »
As mentioned, IS changes the camera model (intrinsic parameters) in a non-reproducible fashion.
HOWEVER, despite this obvious error introduction, what are the "real world" implications?

I'm sometimes confronted with projects, where there is little chance to optimize the image capture process (i.e. using a long monopod without the possibility for additional artificial lighting).
Images with motion blur in such a situation almost certainly introduce more reconstruction errors than IS-images?!

Does anyone know of any scientifically evaluated comparisons (i.e. controlled setup) between IS v.s. non-IS?
My guess is, that IS-images will introduce more noise (assuming oblique image-cature scenarios with solid  projection angles).

Otherwise, this "IS-subject" remains foggy...

cbnewham

  • Full Member
  • ***
  • Posts: 115
    • View Profile
Re: image stabilisation - yes or no
« Reply #6 on: June 16, 2021, 12:38:39 AM »


I'm sometimes confronted with projects, where there is little chance to optimize the image capture process (i.e. using a long monopod without the possibility for additional artificial lighting).
Images with motion blur in such a situation almost certainly introduce more reconstruction errors than IS-images?!


What about increasing the ISO?  I have mine very high and most of the noise is removed when I process the raw files to jpg.

As to IS, it would be an interesting experiment, but probably hard to do because you can't really replicate the exact camera positions IS/non-IS if hand-holding the camera. So any models will not really be directly comparable for accuracy.


3create

  • Newbie
  • *
  • Posts: 11
    • View Profile
    • 3create
Re: image stabilisation - yes or no
« Reply #7 on: June 16, 2021, 01:07:53 AM »
Good points!
But 400 ISO is the max for my APSC-cameras (and weight + depth-of-field are constraints for higher mounted cameras).

Yes indeed, maybe someone could come up with a cool concept for IS-comparisons:
i.e. a reproducible robotic motion rig ;)

cbnewham

  • Full Member
  • ***
  • Posts: 115
    • View Profile
Re: image stabilisation - yes or no
« Reply #8 on: June 16, 2021, 11:53:42 AM »
Good points!
But 400 ISO is the max for my APSC-cameras (and weight + depth-of-field are constraints for higher mounted cameras).

Yes indeed, maybe someone could come up with a cool concept for IS-comparisons:
i.e. a reproducible robotic motion rig ;)

I was thinking along those lines. The rig would have to jiggle the camera like a human would. Not beyond possibilities - but it would be expensive. There must surely be a better way to test this.

Possibly determine how many pixels shift there is and then crop a series of images with random offsets by up to that number of pixels to make sets of pictures to use to make the models. One would need to strip the Exif Metadata from the images - but that's no big deal. I usually strip it from mine and find MetaShape works just as well.

Bzuco

  • Newbie
  • *
  • Posts: 49
    • View Profile
Re: image stabilisation - yes or no
« Reply #9 on: July 28, 2021, 03:56:39 PM »
I made an attempt. I took six photos of graffiti wall, one row from left to right. First(img 2669-2674) and second(img 2675-2680) attempt was with stabilization off and third(img 2681-2686) with on. I was taking photos from about the same positions and I was pointing to the ~same positions on wall. At third attempt I was slightly far from wall(~30cm), but nothing critical.
My expectations was that 1. and 2. attempt should results in the same pointcloud and 3. attempt should be slightly or significantly different pointcloud.
My expectations were confirmed.
Additional info:
I was taking photos "quickly" holding camera with one hand trying to not move. Manual exposure 1/400, ISO100, F4.0, auto focus on, 5184x3456 jpg, 24mm lens.
Alignment params:  Accur. High, preselect off, key limit 20000, tie limit 0, rest options NO.
Dense cloud: Ultra high, filter aggressive
View matches table also confirmed, that stabilization ON is causing more invalid points...I compared one photo in the middle of the wall with it's two neighbours.

You can comapre 3 rasters from link below to see differences (e.g. in photoshop set difference layer blending mode). Images are ~1pix = 1mm and I was ~2.5m far from wall.
https://www22.zippyshare.com/v/esWhdJBJ/file.html  (23.6MB)

I will be glad if somebody can confirm that this experiment is enough to confirm, that image stabilization brings deviations in point positions. But I also suppose that If I would be holding breath and taking photos after 2 sec. of not moving camera(let stabilization finish its job and return position to center of the chip, etc.) then I would get almost same results as with stabilization off.

Kiesel

  • Sr. Member
  • ****
  • Posts: 251
    • View Profile
Re: image stabilisation - yes or no
« Reply #10 on: July 29, 2021, 04:26:48 PM »
When I think about it, the wobbling can't be imitated reproducible, but the opposite can.
So two test sequences one with the camera on a tripod and stabilization ON and the other with stabilization OFF should show the effect of it nicely.
Perhaps this test can be expanded by a third sequence with a leaning tripod in different directions for each shot and stabilization OFF.
The camera calibration results for the sequences should show some differences.

« Last Edit: July 29, 2021, 04:43:35 PM by Kiesel »

wojtek

  • Full Member
  • ***
  • Posts: 240
    • View Profile
Re: image stabilisation - yes or no
« Reply #11 on: July 31, 2021, 02:11:49 PM »
Most datasets carry larger issues than the miniscule variation an IS on/off ever could in my opinion. Introduce small shake/blur to any of the pictures and you have a larger issue that a tiny shift of some sort.

Paulo

  • Hero Member
  • *****
  • Posts: 752
    • View Profile
Re: image stabilisation - yes or no
« Reply #12 on: August 01, 2021, 08:48:24 PM »
I would perform a test capturing same scene/object once with IS on and once with IS off.

Since IS theoretically changes the camera interior parameters, in case of IS on, I would set Image variant parameters for f, cx, cy in Camera Calibration Initial Tab to see if this improves the result....

just a suggestion that someone with IS camera could do....

Using image variant option for f, cx, and cy will estimate a value for focal and principal point coordinates for each image in the set and should ideally improve the optimization,,, see attachment wher I set f, cx, cy as Image variant and adjusted tab from Camera Calibration now has different values for these 3 parameters for each image...
« Last Edit: August 02, 2021, 01:27:02 PM by Paulo »
Best Regards,

Paul Pelletier

jrp

  • Newbie
  • *
  • Posts: 49
    • View Profile
Re: image stabilisation - yes or no
« Reply #13 on: August 09, 2021, 05:03:39 PM »
This is a very complex question indeed.

Being somewhat of a purist, I insisted we went to the lengths recently when setting up a lab to specifically to large volumes of small object photogrammetry, of selecting a model of camera and lens that had no IS functionality, as I didn't trust that even with it off, the sensor would be properly centred. It was also a good value proposition otherwise (Sony a6400 + 50 FE macro).

A modern IS system can have up to 7 variables used in IS simultaneously (if I recall):
  • the sensor can translate in 2 directions, which is equivalent to Cx and Cy
  • the sensor can be rotated around the optical axis -- this should look almost like the camera simply being rotated, so should be fully corrected with basic position optimisations
  • the sensor can rotate around the other 2 axes, which could do all sorts of unpredictable things to the results
  • an optical element in the lens can move in 2 directions to give similar results to the sensor translating, minor optical aberrations may be introduced here

Notably, neither focal length nor focus point should be affected by any of these. In theory. (I’ve also been debating whether changing focus between images could have similar issues, but that’s a different discussion. And don’t get me started on rolling shutter effects on all of the above.)

Also, do remember that IS can allow slower shutter speeds, which can allow lower ISO or smaller aperture, which may increase sharpness or reduce noise in the image, which may have other positive effects.

There is also a huge, variable that I can't think of a way to evaluate: we know that the motions can move during the capture (which are only moderately controversial as they at least attempt to keep the image as it is at the start of the exposure), but how much does it move before the capture? If the implementation has a very low distance for this, it's likely better on than off. I know some implementations turn IS on when the user half presses the shutter. The only thing that I can say is that we can basically guarantee that it will be as good as random for every shot up to an undetermined maximum in each direction as it’s based on the details of the dynamics of the camera shake at that time.

Remember that IS on with a tripod is often recommended against by manufactures, and it can straight up reduce image quality. IS is specifically designed and optimised to compensate for human hand shake.

In short, I have no idea, I'd love to see a well run study into this though, that covers all the variables.