Using DroneDeploy and the POI mode for automatic point cloud mapping

Using DroneDeploy and the POI mode of DJI.

Have been doing some leaf-off flights now in March on one of my favorite sites for complex tree crown point cloud mapping. To add to the leaf-on data from last autumn.

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Fig.: Leaf-Off point cloud with combined height color coding and reflectance color coding.

This time I also checked the full automatic flight modi using the POI (Point Of Interest) mode from DJI and Drone Deploy with the P4Pro and the P3A.

Both work perfectly although I believe the POI mode can be dangerous when its done with low altitudes. You have to carefully check that the radius is free from obstacles when you define the center position, altitude and distance from center (radius) for the POI flight. When POI is started it begins with comparably low speeds. You can modify the speed setting when the POI mode started. Unfortunately you cannot modify this stetting before you start. Tuning the speed on an iPad or (even more difficult – on an iPhone) is kind of dangerous because you easily move the slide too much to higher speeds than wanted and the copter will immediately accelerate and start circling your POI object like crazy until you managed to move the slider to slower speeds. There is however always this stop button to kill the POI mode – this is handy and needed sometimes. When you press the stop button the copter stops the POI mode completely and waits for new commands.

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Phantom 4 Pro – lens flare issues

Some more tests with the Phantom 4 Pro: one major “issue” with this system for stills / photography is imo clearly the flare sensitivity of the lens/sensor combination. The into the sun shots just capture a lot of flare and the sun star is very much Samyang 14mm like. This is an issue and it reduces the image acuity for 3D point cloud modeling for object measurements as well as for the landscape panorama approach.

The against the light shots look very much like the Samyang/Rokinon  14mm lens character. The sunstar has light rays that increase in size from the center and these rays cover the full frame of the 1inch sensor when the illumination comes from one of the outer edges. It clearly degrades the full image when the lens is stopped down to f.e. f8 but gets better when the lens is driven wide open. There seem to be some diffraction effects at work that are clearly not so great. You can drive the camera to generate sharp sun stars, but as usual here the characteristics of this star make a difference to some of us.  The Samyang like star is not so well received. The linked flare issue is much more a problem because it is hard to avoid when you have the sun in your frame. For some scenarios a lens hood may be useful but its only functional for those shooting scenarios where the sun is not within your FoV.

To be honest I am bit puzzled … this is the first affordable 1inch sensor platform with nice resolution and better DR, but – the flare issue is likely killing some of the potential ideas that you might develop with this machine.

Some examples:

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@f4 things get a bit better, but with this image below also the light levels have changed:

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Comparison shot done with the Phantom 3A, clearly shows that the lens/sensor combi wont give the same amount of flare here (again different light level and different sun illumination angle):

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mtk, Sören

Phantom 4 Pro arrived

The Phantom 4 Pro arrived – first integration tests started and I am testing the image quality of the 1-Inch sensor – at least from my perspective the most important part of the new P4 series. Especially comparing dynamic range and sharpness to the tiny P3A sensor/lens combo and systems will be interesting (which is similar to the original P4 sensor).

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