Rolling shutter optimization: is it OK to set this as a camera default?

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hi there!

I am processing imagery captured with the Mavic 2 Zoom. Using your “vertical pixel displacement” calculator, I was able to deduce that rolling shutter optimization should be chosen to process these images. It did, indeed, greatly improve the results.

Is there any reason why I should continue to use this calculator before processing images from this camera, or should I just alter the camera default settings to automatically do this? Could using this setting be detrimental to results if it’s not recommended based on the flight height and speed?

Thank you!

2

Hi @FYBR_SOLUTIONS,

You handled the problem very well, you used our vertical pixel displacement tool exactly when it was necessary. Congrats!

Please visit another post related to the same topic: Rolling shutter gain
In the comments, read Blaz’s reply from March 2018.
I believe it will answer all your questions :slight_smile:

Best!

3

Hi there!

Thank for you the link. I have read this answer in full and it’s been very informative. My question is related to Antonio’s first question in this comment:

Well, as you say “enabling the option could produce better results.” is an admission that it may be or not, isn’t it?

Is there any danger in enabling rolling shutter correction even if not advised by the vertical displacement tool?

I am aiming to avoid processing Step 1 more than once. It seems as though the recommended processing flow (if you’re not aware of your flight height & speed) is to run Step 1, check if there are signs of rolling shutter distortion, change camera settings to enable rolling shutter correction, and re-run. Can I just enabled rolling shutter distortion correction by default? Why or why not?

Thanks again!

4

Hi,

Rolling shutter algoitrhm will work with any rolling shutter cameras, however we have tested only some. It is recommended to use the rolling shutter algorithm when the Vertical Pixel Displacement is bigger than 2.

The downside of applying the Rolling Shutter Optimization when the estimated pixel displacement is lower than two pixels is that overall processing time may increase. In some cases, it may introduce error into the final results. While the increase in error is not guaranteed for all projects when applying the Rolling Shutter Optimization to images with a pixel displacement lower than 2 pixels, it is possible, as evidenced by the Phantom 2 Vision results when flying approximately 1 m/s.

5

Beata,

Thank you for your reply!

I am concerned that I may have used the vertical pixel displacement tool incorrectly. I used shutter speed in place of sensor readout time, which I have since learned are not the same thing.

This article gives the sensor readout time for some common drones: https://www.pix4d.com/blog/rolling-shutter-correction

do you have any tips for getting the sensor readout time for the mavic 2 zoom (or any other camera)?

6

Hi @FYBR_SOLUTIONS,

Thank you for the follow-up.

Actually, we’ve recently had an internal discussion about the Rolling Shutter algorithm.

Here are some insights:

  • For the camera that has a rolling shutter, you could have the rolling shutter algorithm enabled by default. Especially if you typically use similar flight parameters (flight height and speed) and you are able to see an improvement when using the algorithm. For example, for DJI Mavic 2 Pro where the influence of the rolling shutter was quite noticeable even at lower flight speeds, we already enabled the rolling shutter to be used by default.

  • The Vertical Pixel Displacement is a great help. However, you shouldn’t ruthlessly depend on it.

  • As a side note, we don’t recommend using zoom lenses for photogrammetry data acquisition. As mentioned in Step 1. Before Starting a Project > 2. Configuring the Camera Settings article

    • The zoom should be stable.
    • Fixed focal length is recommended.

Best

7

Hi Beata,

These seems like some good tips. Thank you again for all your help!

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