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

microsd

 

 

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.

sp-stand-leaf-off-2

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 “Using DroneDeploy and the POI mode for automatic point cloud mapping”

“Drohnenverordnung” in the Federal Council

Regulations to fly copters  the “Drohnenverordnung” went through the Federal Council – the 100m regulation will be redone. Overall good news for those of us who fly for research or commerical projects. The ascent permission for copters below 2kg/5kg  was skipped. This will make it much easier to fly within legal regulations.

https://www.heise.de/newsticker/meldung/Drohnenverordnung-Bundesrat-erhoert-die-Modellflieger-3649944.html

http://www.bundesrat.de/SharedDocs/drucksachen/2017/0001-0100/39-1-17.p%20df?__blob=publicationFile&v=1

http://www.bundesrat.de/DE/plenum/plenum-kompakt/17/954/079.html?view=main%5BDrucken%5D

drohnenverordnung