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M300 P1 Focus settings for photogrammetry
1438 5 4-6 09:47
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Ryan H.
lvl.2
United States
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DJI Pilot only gives you two focus options- first waypoint autofocus and calibrated infinity focus. We chose first point autofocus, but when we did our battery hotswap partway through and sent the M300 back up, it pulled another autofocus before completing the rest of the mission. Obviously this makes post-processing much more difficult when you're dealing with 2 sets of images that each have their own focus values, as they require separate camera calibrations in photogrammetry post-processing.
  
My questions are:
  
  • Where are DJI's detailed instructions of how to calibrate the infinity focus?
  • Does DJI Pilot allow you to set the focus once for the entirety of the mission, or even the entire day? The GUI with the wheel on the right-hand side of the screen from infinity focus to macro is not useful for photogrammetry (unless I'm missing something) because you want to choose the same value every time. It should be a slider bar with the value displayed and you should be able to type in the value.

4-6 09:47
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Craig_Tas
lvl.4
Flight distance : 2596627 ft
Australia
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1. infinity focus calibration instructions are found on the controller when you go to set it to infinity focus, it will display what you need to do.
2. The drone will use Auto and then switch to manual for the rest of the flight and as you have found when you land and take off again to continue it will do the same again once it reaches the location of the paused mission and continues. I don't think there is a option for the pilot to set the focus but someone else here may know more.
4-6 15:33
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fans5b25584c
Second Officer
Flight distance : 24012 ft
United States
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The M300/P1 platform is a magnificent tool, but this has been a problem for us from day one, as we fly over islands, and if you don't pull a silly work-around in the mission definition, the first waypoint could be over water.

If the wind isn't blowing and the water is smooth, there is a high probability that the first autofocus will choose a random focus distance, and every image for that entire flight will be out of focus.

Sometimes severely out of focus.

The problem is that you don't know you've wasted an entire mapping mission until you get somewhere that you can look at the images in high resolution.

For us that means a wasted day and a wasted boat ride.

If you fiddle with the mapping area, margin, and mapping angle values you can get that first waypoint to happen over land.

Just silly

If anyone knows a solution, I'm also anxious to hear about it
4-7 06:52
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Ryan H.
lvl.2
United States
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fans5b25584c Posted at 4-7 06:52
The M300/P1 platform is a magnificent tool, but this has been a problem for us from day one, as we fly over islands, and if you don't pull a silly work-around in the mission definition, the first waypoint could be over water.

If the wind isn't blowing and the water is smooth, there is a high probability that the first autofocus will choose a random focus distance, and every image for that entire flight will be out of focus.

That's good to know, I never even considered that as we haven't had any flights over water yet. The focus value is a big deal in photogrammetry processing, as it essentially determines the location of the ground data vertically. Theoretically you can generate a camera calibration with a known focal value, and use the same focal value on the next flight and have a great starting point when you get into photogrammetry processing. It seems to be a big oversight in DJI Pilot.
4-7 07:41
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fansf6d92895
lvl.1
United States
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Ryan H. Posted at 4-7 07:41
That's good to know, I never even considered that as we haven't had any flights over water yet. The focus value is a big deal in photogrammetry processing, as it essentially determines the location of the ground data vertically. Theoretically you can generate a camera calibration with a known focal value, and use the same focal value on the next flight and have a great starting point when you get into photogrammetry processing. It seems to be a big oversight in DJI Pilot.

I am noticing the same issue.  Is there a best practice specified by DJI for focus.  In traditional photogrammetry the number one requirement is a fixed focal length.  Changing the focus changes the focal length.   I am especially concerned about this for multi battery missions, but have also noticed some unreliable results in elevation for single battery missions.  Focal length directly correlates to elevation.  I have concerns that the focus may actually be drifting mid flight even on a single battery mission.  Please post more on this topic.
4-7 10:17
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AIRWORKS.
Second Officer
Flight distance : 2907746 ft
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Australia
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Ive been shooting digital twins and setup the infinity focus before the first flight and hot swap batteries but the manual focus dial is right there where i need to press to format cards and change any settings, is there anyway after doing the calibration to lock focus and hide this menu?
9-16 16:46
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