Copter based motion-time stacks

Some of the new interesting perspectives of copter based regatta and yacht photography clearly come with time series visuals – or as I would rather call it: “motion-time stacks”. Its not new in sports photography and with fast cont. autofocus and high speed cont. shooting speed we have seen it in motorbike sports, skiing , swimming and especially with athletics and dancing. The appealing aspect is that you can tell a (very short) story with these stacks. The image reveals a series of decisions and is much more than a capture of a specific situation.

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With UAV visuals you can create comparable shots – mainly possible due to the precise GPS controlled position hold of the modern quadrocopters – especially the DJI Phantom series. The lat/lon/altitude position is very precisely corrected and together with the gimbal correction you have only minimal changes of the area covered with the FOV of your camera.  Combining different situations at the same position is more a question of how to post process the time series and how to combine the changes into one image. With the new Phantom copter generations you can easily leave the copter at a specific place & altitude and let it capture the scene while shooting with a DSLR at the water level.  The only problem are winds above 5Bf  and/or gusts that exceed 5-6 Bf. The copter drifts away and you would have to manually move the copter in S-Mode to get back to your start position. Flying freely without VR-googles is also not too much advised when you do not have constant visual control of the copter position. You easily loose track where the copter exactly is. The standard RTH function does not work on water (you usually drift on a small rib, when you trigger RTH the copter will fly towards the position where you have been – not to where you are now)  – though flying back to sender (and not to the start position) is helpful and implemented in a way as you can update the  “Home Point” manually in the Phantom series control software when you have a GPS enabled controller device (iphone/iPad). This can safe your copter because on water you easily loose track where exactly your copter is. RTH with the hover option enabled (you do not want the copter to land automatically!) is a great function as long as you update the home point regularly on the boat. Thats the function that I trained a couple of times for these not so nice moments when you believe that you lost control and the battery warning noise is slowly eating your coolness. Btw: updating the controller position should be set with a shortcut once selected – its the function that you want to trigger every 20sec or so on a boat. I dont understand why this is not already implemented in the DJI GO app.

The „Dynamic Home Point„ feature of the Inspire copter controller software (version update 29.05.17) is also a  very remarkable feature in that context. It updates the position of the „Home Point“ using the controller GPS information. The RTH function is in that form a really useful function again.  This is by far the most secure option for flights over water where you start from a boat but it doesnt create safe automatic landings on a moving boat! Landing is usually by picking the copter in air by hand. Its the reason why the Phantom series works well here: you can easily pick the copter up by its legs.

Some picture examples that I did in may/june 2017 to find out what is working are attached here. Imo you either fly very high (you need a permission for above 100m!) or very low – approx. 20m – to get exciting perspectives – the in between wont make it in my opinion. Low flying is difficult, you often  cannot clearly define the relative height difference to the boat rigs and you do not want to distract peoples attention. Very high positions are nice to capture the field at the start leg or at the luv position but even with the 20mm (equiv) of the P3 you will need 150-250m flight altitude – and clearly a BFA permission to go that high.

To create appealing visual compositions you have to pre-visualize the direction and possible crossings of the boats – that is really the most challenging part. I usually try to get a fixed position close to a turning point where maneuvers take place. There are endless option how to combine light and action into something appealing. With the wide angle 20mm equiv. camera system of the P3 one always collects sun glint that will mess up the stacking process later. Its hard to avoid but you can try to keep at least the action out of the glint region and it can be also nicely used as part of the composition.

With the new copter regulation in place for Germany its easier to do commercial/research work than it was before. Mainly because you do not need an allowance for every flight from the regional authority anymore. There is a general clearance for commercial flights below 100m, and below 5kg weight in place. Above 100m and in EDR zones and some other restricted region-types a special permission is needed (an insurance is also a given).

In Berlin the EDR4 is blocking the south-western part of the Havel – so everything west of the “Kälberwerder” island is very clearly within the EDR4 zone (a restricted flight zone around the HMI experimental nuclear reactor). For this year for the “Havel Klassik” regatta race I applied for a clearance (that I received already) because the interesting visuals are all west of the Peacock Island and fully within the EDR4 zone.

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I will add some more shots here in the future to make this post a diary of the experiences with the P3A and the P4P from DJI. So stay tuned.

Sören

MicroSD cards and standards …

There is a lot of confusion about the speed of MicroSD cards these days and various standards exist. Overall its easy to buy yourself into the wrong card type and for copter data acquisitions with the P4Pro the card speed is essential.

So here we go:

UHS-I and UHS-II (Ultra High Speed Classes):

UHS-II is the newest standard but is not supported by many yet. The Phantom series 3 and 4 all need UHS-I and definitely the fastest UHS-I cards. The UHS-I bus goes to 104MB/s whereas the UHS-II bus goes up to 300MB/s  (theoretical limits – the cards will not perform at this speed).

u1-u3 Rating:

UHS Speed classes are subdivided in to u1 and u3, while u3 performs minimum at 30MB/s write speed (needed for copter flights).

Video Rating: 

A new speed rating is called “video rating”. It scales from V6 to V90. The fastest cards are v60 right now (possible values are V6 V10 V30 V60 V90, but note that V60 and higher is usually UHS-II bus type and not supported by Phantom 3 and 4 series).

C-Rating (c1-c10)

Speed Rating up to 10MB/s write – this is a slow class rating and c10 should be always possible for fast cards.

SDHC vers SDXC:

Up to 32GB capacity the cards have the label microSDHC whereas cards bigger (64-256GB) hold the label microSDXC.

For the Phantom3A (5MB/s max write speed) Phantom3Pro (60mb/s =7.5MB/s) and Phantom 4Pro (100mb/s=12.5 MB/s) series the fastest at writing to card seems to be right now the UHS-I SanDisk Extrem plus and Extreme pro cards (90MB/s sequential write). While this seems overkill the u3/V30 just certifies that you will never be below 30MB/s write speed under real world / all temperature conditions.

  • SanDisk Extreme PLUS  microSDXC UHS-I u3 V30
  • SanDisk Extreme PRO microSDXC UHS-I u3 V30

Nice summary from Wikipedia goes here:

https://it.wikipedia.org/wiki/MicroSD

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Drone Deploy and DJIs POI Mode copter image acquisitions

Using DroneDeploy and the POI mode of DJI  (this article was first published on jenacopterlabs.de).

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.

Continue reading “Drone Deploy and DJIs POI Mode copter image acquisitions”

Schlachtensee Panorama

The higher resolution version of the Schlachtensee Pano shot / panorama from early February. This was a magic week. Temperatures and light were just perfect and the ice was incredible untouched. This pano is from the P3A.

For those not familiar with the Berlin south west. The Schlachtensee region is known in Berlin as the area where the people who love dogs used to have some conflicts with those that go for a run and/or the other way around.  I think the conflict has been cooling down now somewhat fortunately! In summer its great to have a swim here early in the morning. Skating in winter only works every 5-10years – so these days in February were kind of unique. (Pano from 4 different shots: resampled to 4300×1300).

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Phantom 4 Pro Flare Tests

Did some more tests with the Phantom 4 Pro:

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 however is much more a problem because it is hard to avoid when you have the sun in your frame and when the lens is stopped down to f8 or f11. 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 1-inch 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. A pitty!

Some examples:

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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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Phantom 4 Pro Tests

Have done some tests with the new Phantom 4 Pro that I am using in 2017 for some research projects on photogrammetric point cloud mapping. This is a remarkable step forward in terms of image quality. The Phantom 4 Pro just creates much better image detail and acuity and resolution/sharpness is on a much higher level compared to the Phantom 3A. Its just giving back the DSLR like quality on tiny airborne systems. Also SNR (signal to noise) is much better and dynamic range ist enhanced. Only problem so far seems to be a slightly higher sensitivity to flare but I have to do some more analysis on this one. Its difficult to compare the flare issue because you cannot create exactly the same exposure / image concepts for different copters in the air. It will always be a wee bit different. So some ground based comparison needs to be done here.

This is a game changer for photographers that need an airborne system sometimes. As simple as that. It brings the image quality that we wanted back and you always can add HDR and Pano techniques to add from that. Great times to let your creativity fly!

Some shots from recent test flights with the P3A and the P4Pro:

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Multi Copter Photography and Photogrammetry

Multicopter Photography and Photogrammetry

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Late this year I bought a Phantom 3A (Advanced). The prices went down and these platforms are so affordable now that it makes sense to test it out.

The main applications for my work are multifolded:

  1. Special shootings for paying clients,
  2. regatta event shots from above,
  3. very early morning misty landscape stills and
  4. large scale or near range photogrammetric mapping for research purposes with applications in forest biomass mapping and archaeology as well as biotop-typ delineation and fine scale analysis of vegetation structure and slope stability analysis.

Clearly 1-3 and 4 will very nicely cooperate. Its just wonderful to experience how photography and research can come together here, makes me wonder sometimes how I managed to get into that cool spot where I get payed to fly a remote controlled camera … :-)

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Being not new to copter flying, I found the Phantom 3 to be really easy to fly. Once you mastered the documentation and some basic theory about controlling a quadro-copter its really a simple excercise to control these devices. This is mainly due to the perfect GPS controlled position hold of the Phantom. It just stays where you put it (in opposite to gliders) and this makes it also kind of boring to fly a copter. The DJI GO app that is used on a mobile device to check the telemetry data and to control the lifeview provides a nice overview about position, viewing angle and overall status of your copter. You can also modify shooting parameters, change the camera viewing direction and check speed, height and remaining flight time, battery status and the number of satellites. Other apps support fully automatic mapping modes with variable overlap configurations (Data Mapper or Drone Deploy).
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P3 installed on a LowePro backpack fully functional with installed props and ready to fly in a minute.

Some DJI Phantom 3 A Specs:

  1. Image Data capturing in 12MP Adobe DNG RAWs, gimbal stabilized! & damped. 2. HDR with 5 exposures each 0.7EV under/over-ex-> RAW DNG HDR computation. 3. Sony EXMOR 1/2.3“, 12.4MP, 94°lens (20mm focal length equiv. tilt.), ISO100-3200, 8-1/8000s, single shot, multiple shot, exposure series (3/5), DNG RAW format, video: FHD upto60p, 2.7k upto30p, 4. Memory: MicroSD up to 64GB cat10.
  2. Control: GPS/GLONASS controlled position hold, visual Realtime-Position-Tracking (VPS – Vision Positioning System) up to 3m flight alt. (P4pro: 10m). RTH (Return to Home Funktion), Battery Low RTH, Security-RTH, software controlled flight altitude (override possible): 120m, autostart/-landing, beginner modi, (OrbitModi/anti- collision (infrared/ultrasonic)/ActiveTracking/terrain follow: P4/pro/Mavic), P-GPS – GPS controled stabilising (+/-10cm position), P-OPTI (optical position control & stabilizing), P-ATTI modi (flight altitude only (barom.) – copter could start to drift).
  3. Flight parameters: weight: 1280g, climb: 5m/s, descend: 3m/s, Vmax: 16m/s (ATTI) – 60km/h, flight altitude max: 6000 m (airspace above 100 m needs a clearance (approval), RC max distance: 5km, flight time: 23 min (30min: P4pro), RadioControl: 2,4khz RC with iPad/iPhone (build in DJI Lightbridge System), realtime lifeview control per DJI GO App.

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