Hi there everyone!
I'm really quite new to this, all of this. In fact, this is my first post.
I first became interested in this project entirely by chance; I happened upon it while looking for small aircraft that can be used in aerial surveys. I've noticed a few other users have a fair amount of interest in the same topic.
Ultimately I will end up building a drone to capture aerial imagery and use the software I normally use when doing a standard aerial survey (with a much larger Cessna) to produce a DTM. But there are a few things that are still up in the air (...nice pun...) - Life will be so much easier if the IMU could export the inertial measurements at the exact time that the camera takes a photo - is this possible? And to what sort of accuracy?
I know that this is not a prerequisite, but in practice, having your external orientation already computed - in the form of photo ID; x; y; z; omega; phi; kappa - is a real time saver. Rather than manually finding tie-points (because the computer is just hopeless at the task) and having to take ground control.
With the IMU capable of spitting out these readings, a quick survey of an area can be done at low cost with a quick turnaround time. Perfect for disaster relief and the like.
Has anyone had some experience with this? What are the IMU reading like with the ArduPilot?
Many thanks!
K.D
Replies
I bumped into the same GPS time stamp issue which is mentioned in this topic. What I can deduct from the logs is that:
The time stamp in the *.log files are in ms, UTC after midnight. This time is send along with the GPS signal, calculated based on an expensive atomic clock in the satellite. Pretty accurate... . However, in the beginning of my logs, I do not have any GPS lock yet, so I guess the time stamp which is logged, is the time passed from when APM was initialised. As soon as there is a GPS satellite connecting to the APM (one would be enough), there is a shift to the GPS time.
I also explored the hidden feature "Geo Ref images". Nice work, and saved me time to parse the lat/long with each picture myself. I have noticed that the program converts the log time stamps to the time as defined in your PC. As I have set my camera internal clock to UTC, the georef to did not found any matches. After I changed my PC internal clock to UTC the program found a correct match (I checked times and coordinates), but advised me to change the offset. This is the log:
Log min 24/05/2012 0:00:12 max 24/05/2012 21:03:43
Photo Bixler_20120524_210334 time 24/05/2012 21:03:34
Photo Bixler_20120524_210334 24/05/2012 21:03:34 vs Log 24/05/2012 0:00:12
offset should be about 75801.214
MATCH Photo Bixler_20120524_210334 24/05/2012 21:03:34
I guess I will have to live my virtual life with this PC in London from now on and just ignore the offset indication.. unfortunately, my programming skills do not allow me at this point to change this myself in the code.
One nice-to-have question remains: Is it possible to add the roll/pitch/yaw information to information which is linked to the pictures?
Dries
as is the procedure to set the time of the camera with the time of the file. tlog?
as the time of the file. tlog?
jim
Hi All, Newbie (ish) here... I have a few questions about the photogrammetry proceess, I've had a read through this thread, and a few of the links from it. And i would like to create some digital 3d surface models from aerial photographs. and would just like to get a firm understanding of the process to follow, please could you correct me if i'm wrong,
1. Take a series of photographs facing vertically down from the aircraft. (I believe APM2 has the facility to stabilize a camera gimbal if the plane is not quite level using pitch/roll servos)
2. Use an Orthophoto program to remove distortion in the photos
3. Use a stitching program to stitch the photos together
4. Insert this large OrthoMosaic into a program that creates a 3d image from it
As a novice, are there any programs i can use to do this manually? Or is the only way to buy a very expensive computer program? or is it best to leave it upto the pros?!
I am in the process of building an aircraft to do this, but it looks a bit complex!
Cheers :)
Hi KD
What kind of SW do you use? And which aerial system do you mount on a Cessna?
My company, Icaros Geosystems has an aerial system we mount on any Cessna and more important for your current needs we have developed the IPS (Icaros photogrammetric software) that allow you to solve images position, create seamless colour balanced Orthophotos and extract accurate automatic DTM with no external orientation nor ground control points. we are now offering its “light” version for UAV use.
With our SW you can extract tie points automatically with no manual work.
Of this interest you, ill be happy to provide more details here or you can contact me in av@icaros.us
Good luck with your new venture
Avi
Rigel,
the log uses gps time stamps. so they cannot be wrong. if anything its not your camera causing the issue? check the image timestamps as well.
Michael
Hi, let me introduce myself first.
NAME : Darko Car
COUNTRY : Croatia
PROFESSION : Surveying eng.
COMPANY: Cadcom d.o.o.
I've been doing aerial surveys with the MK Oktokopter for a year now. Till now I had about 12 nice missions done. Each of those missions had at least 1 to 6 takeoffs since MK has a limit of 250 meters radius around the takeoff point.
HARDWARE CONFIGURATION : MK Oktokopter + hommade graphite camera gimbal,
CAMERA : Sony NEX5 (hopefully NEX7 soon) + Zeiss Distagon 18mm
SOFTWARE : Photomde 5 - full configuration (racurs.ru)
+ RTK GNSS receiver connected to the state VRS for GCP survey.
Till now I have made projects with the highest resolution of 5mm (ground resolution) up to 5cm. That 5mm project was a tiny archeological site (20x20 m) and for the regular DTM-s + DOP-s I am using 5cm resoultion with the 170m flight above the ground.
Since last project which was photographed a month ago I didn't have a problem at all. The last (sixth that day) takoff point the MK just flipped ower and crashed at the ground. The dammage was minimal, just one prop was broken but for some unknown reason (could be high moisture) it refused to fly.
The reason I am switching to the ArduCopter is the 250m limit. I've just bought the Hexa from Jdrones and the only thing I have done on the first flight is that I have broken all six props. The plastic is like a glass, just touch it and it's broken.
Now I have much better props (12) with the strong engines and at the begining of the next year I am planning to make first test flights. For now I dont know how to solve the camera stabilisation with the Ardu. But the first tests will be done with the bag full of send and 2x 8000 mA (3s) LIPO-s and what I am really interested is what's the area I can cover with one flight. What I don't know is what's the actuall speed of the Arducopter while flying in a program mode.
Regards,
Darklo Car
One way to link the photos to the telemetry data is to have the telemetry data time stamped.
Then the photos time stamped. Then a simple app to write the telemetry data to the photo exif data corresponding to each time stamp. You just have to make sure both camera and APM are running on the same time.
Hi all, this thread is very interesting for me, as it's my next plan of attack after finishing my Hexacopter. I work in construction for a large global company, and I work in engineering and land surveying. I am thinking of using the ritewing zephyr as the basis for my survey platform and of course APM as the flight controller. I have seen a couple of demo's of the sensefly swinglet cam and to be honest it wasn't very impressive and cost £10,500. The plan I have is to overlay photographic information over an exisitng DTM, identifying control points from the DTM in the aerial photographs, if we use quite a few control points then the photo overlay should be able to be rectified quite accurately.
Have any of you guys ever seen this
http://www.microsoft.com/ultracam/en-us/default.aspx
Has anyone tried Hugin? It should make mosaics? Who makes one button solution or writes instructions for making mosaics?
http://hugin.sourceforge.net/
Then there is also commercial EnsoMosaic. Price is about 5000USD.
http://www.mosaicmill.com/products.html
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