Hi Everyone
Im putting together a UAV for aerial surveying using stereo photogrammetry.
Id like to get some input for the experts before going ahead.
My plan is to buy a high wing trainer coupled with an APM2.
Electric powered with a gyro camera mount.
The software Im using is photomodeler scanner. It can do DSM.
Im quite a n00b when it comes to fixed wing, but I have got a fair amount of expericence on multi-rotors.
Im doing this on a fairly tight budget and need to know a good camera to use.
Any advice would be greatly appreciated and will gladly buy any1 a beer if you're ever in South Africa :)
Thanks!
G:)
Replies
Arga,
Yes, it is ~1 frame per second, we currently use IR and obtain more than enough "vertical overlap", the side-lap is strictly kept at 70-75%, although we will be testing the setup at 18m/s because of the benefits on endurance.
A zoom lens set at 35mm would defy the purpose, prime/standard lenses provide less distortion, better light transmission due to the fact they are constructed by fewer elements.
I couldn't recommend enough a good quality prime lens no matter what camera you are using.
Although ground resolution with the current A7s and 35mm at 120m AGL is lower than using Nex5N with 24mm flown at 60m AGL, even if we keep sidelap at 70-75% for both setups, model reconstruction is far better on the A7s setup. I think it should be no different with the higher resolution A7r although it would increase memory consumption for the reconstruction.
Hope this help
G
In the same boat as you . Thought Ihad the platform (durafly Sky Mule , did the flight time maths on the RTF set up and got an answer of 6mins flight time so back to the Bixer 3 I think.
We get 1h 30mins with 1kg of payload using the Raptor E1
Er and your point is Duffy? This is a very old thread to come back alive in new easier times.
Spot on Gary.
Hey Joe, I wanted to update this thread with a link to the recently developed Piksi compact/affordable RTK solution for UAV use.
http://www.swiftnav.com/piksi.html
What is your opinion of this potential breakthrough? I hope to be testing this in the spring and will post results.
I have learned a lot from this thread to guide my approach into low level photogrammetry, thanks to all!!
Hello Joe,
I have been reading your posts and learning all about aerial photography from UAV's! You really seem to know your stuff.
I was hoping you could help me figure out how you get the overlap of the images you want. Do you calculate plane altitude, speed etc, or have some type of gps driven trigger for the camera as well?
Thanks
Agisoft is def a much better option than Photomodeler, have been assessing a number of digital photogrammetry offerings including cloud upload sites such as Dronemapper & Pix4D, will probably go with Agisoft, used Leica when it was V...
@Gisela & Joe - great, great work (is Gisela loading all those Gb chunks, Joe, while u post? kidding ! ) , am in process of a startup doing v similar in UK/Ireland, have ordered an X8 airframe, had decided on a Sony NEX-7 for imaging but now veering towards Samsung NX200/210/1000...
Re aerial RTK / post processing, one factor that I assume people realise is that the GPS must record either RINEX format or raw signal in a standard format usable by the RTK/post processing software.
I spent a year managing data from an aerial survey research aircraft which had a cruciform GPS setup (i.e. GPS unit fore/aft/port/starboard, & one critical factor was integrating IMU yaw/pitch/roll readings with GPS @50hz, synchronising timestamp info was critical in this case...
Again Joe, excellent setup & project implementation, serious coverage,
Denis Deasy
Red Kite Aerial Survey
No, no info o do this on the net..I opened the camera and traced the wiring I needed in order to connect to the focus and snap connections - need both, even though in fixed focus manual, since we periodically ( every 15 seconds ) just do a dummy focus if not taking photos so the camera does not go to sleep while preparing the flight plan upload, preparing for autolaunch, etc.
It is a real pain modifying the cameras like this, but no other way - cannot use a servo to do it - we take 800 photos on a 1.5hectare area, and have flown over 4500 hectare already - the servos will not last the end to end cycling every 0.8seconds...I have now modified over 30 cameras - 15 Samsung NX200, 9 Canon, and the rest a mix of cameras we were testing.
We never use GPS cameras - we use the aircraft attitudes and position ( from the IMU)and compute the image center on the ground from that and feed that to Agisoft with the photos.
Joe
The NamPilot
Regarding how we control the Samsung NX200 -
I open the cameras and connect wires to the focus and snap switch lines. The camera is then neatly closed with a mini connector located in the battery compartment. This is then controlled by the autopilot during the photo mission. The flight plan is set for the correct height and photo interval for the correct photo overlap for the required GSD.
The samsung lenses are no good for this application - they are fly-by-wire lenses and will not remain at a manual focus setting when the camera is switched off and of again. In auto-focus mode they are too slow and the time between photos suffers - we go down to 0.7sec between photos and the lens insists on refocusing each time. The Pentax 21mm lense is superb - very low distortion. Used with the Samsung/pentax adapter which has a manual aperture ring, so easy to set aperture and take photos in aperture priority mode.
The downside is the weight - camera plus adapter plus pentax lens is around 500grams...
Pentax lens is around 240grams, the 15mm pentax lense , also a VERY good lens with low distortion, is even heavier.
The best lense for this is in fact the Voightlander 20mm or 15 mm lense with adapter. it is half the weight of the pentax lens, perhaps better quality in photo, and the adapter is 12grams compared to the samsung 66grams...I have not managed to find the Voightlander lense in my part of the world yet - B&H camera in NYC have them at good prices.
Joe
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