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[iOS] Pix4Dcapture and Parrot Sequoia captures less overlap with custom camera settings

I have been using the Sequoia for a year now. The app used to have the default settings for the Sequoia in it. When I did an update to the Capture app several months ago, it no longer appeared to have the Sequoia settings in it anymore. Took me a month to figure out that I had to add a new custom camera myself.

The camera image size settings appeared to have changed as well. I used to be able to cover my field easily in one flight at 75% side overlap with the Sequoia image size that was already in the app. Now I can barely get 60% side overlap using the image size listed in the Sequoia manual in the app’s custom camera settings. The resulting image doesn’t seem to have dropped in quality though. Just looking at the flight plan, the rows seemed to be equally spaced out now at 60% as it was before at 75%. Either my image size is wrong from the camera manual or the app was flying at 60% overlap previously when it said 75%.

HI Matthew,

It is possible that the camera specifications that you are entering into Pix4Dcapture’s app settings are incorrect. I have found that camera specifications published online are not always appropriate for planning missions for photogrammetric applications.

However, I anticipate that the latest version of Pix4Dcapture is reporting that you are capturing less image overlap with the custom camera in Pix4Dcapture’s app settings compared to what Pix4Dcapture was reporting when Parrot’s Sequoia was a selectable camera option because of a difference in how the camera’s parameters were defined. The latest version of Pix4Dcapture assumes that the camera has a perspective lens when you enter a custom camera in the app settings. Parrot’s Sequoia has a fisheye lens, so I believe that you are actually capturing more image overlap than what the latest version of Pix4Dcapture is reporting with your custom camera in the app settings.

If you have not seen any degradation in the quality of your results since the amount of image overlap that Pix4Dcapture reported changed and you see that the distance between adjacent flight lines is approximately the same as with previous versions of Pix4Dcapture, I recommend that you continue flying with the same workflow. The key thing to remember in this case is that you will capture more image overlap than what the latest version of Pix4Dcapture is reporting.

To ensure that Pix4Dcapture reports the most accurate image overlap possible, please confirm that you have entered the following camera model specifications in Pix4Dcapture’s custom camera app settings before you plan your next flight. You will still see that Pix4Dcapture reports less image overlap than you capture:

  • Focal length [mm]: 3.98
  • Sensor width [mm]: 3.6
  • Image width [pixel]: 960
  • Image height [pixel]: 1280

Please do not hesitate to let us know if you have any questions.

I had the RGB image size at 4608x3456 pixels in the settings. It’s the same ratio as the single-band cameras so the relative size is the same which means I still have the same overlap issue. With that said, I haven’t really noticed any lost in quality at a quick glance at the images. I am beginning to go through my processed imagery for the last year and can more closely compare the two. I am not sure if it’s tied to the issue I was having with the app being updated and the camera settings not showing up anymore by default. As of last December I was able to cover my area with 2 flights. Then sometime in January and February after updating the app, I was no longer able to cover it without having changed the altitude or overlap settings in the app. 

Matthew,

Great idea, it hadn’t occurred to me to enter Parrot Sequoia’s RGB camera characteristics instead of the multispectral camera’s characteristics into Pix4Dcapture’s custom camera app settings.

I recommend that you continue flying your projects with the most recent mission settings that you chose but that you keep an eye on the accuracy of your results. The Quality Report is a great asset for ensuring that your project’s results are falling within the recommended thresholds for different aspects of your reconstruction.

If you have reason to believe that your drone is capturing a significantly different amount of image overlap than what Pix4Dcapture reports, please let us know and we will investigate the results of one of your most recent projects.

Do not hesitate to let us know if you have any questions.