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Author Topic: aerial photography?  (Read 23453 times)

Wishgranter

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Re: aerial photography?
« Reply #15 on: May 03, 2012, 05:34:18 PM »
Tenyen, the copter for 1.000 are useles, that you mark as you will use it in real enviroment.... but i can be wrong, but im in contact with comunity around it so i know what im write.

For "semiprofessional" use you need at least something in 3.000 euro range and they cannot handle big DSLRs.... use with one of my friend lately....

another thing is to fly with it, need few weeks of testing at least if not months. Battery is another thing they can be used just about 100-150 times and cost something.

im personaly use services of experienced friend with hand glider - sit with him and go shoot what im need, is better than Airplane - lower atlitude fly ( 10-15m :-) ) but every job need another solution.
For walley like mentioned here is best the Airplane, quadcopter is for buildings.

And im trying use services of someone experienced, it cost something but when you work on few project over year is better to use someone services that have experience and equipment....



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Oli63

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Re: aerial photography?
« Reply #16 on: May 03, 2012, 06:33:08 PM »
I am amazed how simple people imagine the process of developing good 3D models to be. With the mentioned methods you are lightyears away from ever getting something useable!

1. You definitely do need an autonomously flying system as nobody is able to remote control a UAV from the ground precise enough to make pictures in equal distances from each other along a STRAIGHT line (not to mention many parallel lines, including constant overlapping in both dimensions). So: forget it!

2. Besides that, it is pretty challenging to develop software that is able to control the UAV in such a way that it flies along lines with a horizontal and vertical deviation less than 2 (vertically 5) meters, including compensation for wind and turbulence. If you cannot, there will constantly be holes in the pattern, as well as too much and too little overlapping to get good 3D data. It took us quite a while to handle this problem.

3. You need a microcontroller on board that is able to release the camera shutter depending on the UAVs position. Otherwise wind will have a great influence on the stability of the picture overlapping factor, which again destroys the 3D data quality. The controller needs environmental data like true airspeed, wind component and so on. Besides, the camera has to be able to fire quick enough. The alternative to set the camery in continuous fireing mode, shooting 2-10 pics per second, won't make you happy as well, as you will get a mountain of pictures which certainly will bring your PC and Photoscan down to its knees.

4. Think of the required payload! The UAV has to be able to carry at least 400 g payload. The mentioned toys are miles away from providing it.

5. You need mission planning software, data about the optical and other performance factors of your camera and lens and have to match it with other control factors of the plane and hardware.

6. It is more than helpful to have a bidirectional data link between UAV and ground station.

7. Be sure: the law is you very smallest problem! In Austria it is - like so often here - not really forbidden, but also not completely allowed. Anyway, they are going to adapt it currently.

8. I don't see how a pilot or a second person on a "real" plane could be able to make pictures which obey all these required conditions. You will always have parts of the plane on your pictures, which alone can drive you crazy when putting the pics into PS. Not to talk about how hard or - in fact - impossible it is to fly along straight lines with minimum deviation without some special instruments. I know what I am talking about, I am holding an airline pilots license.

9. - 30. .............

With other words: much better you tell an expert what you need, pay him some money and get a very high quality result. Even more, as you seem to have more money than is necessary. :-)

Greetings
Oliver
« Last Edit: May 03, 2012, 06:42:03 PM by Oli63 »
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Diego

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Re: aerial photography?
« Reply #17 on: May 03, 2012, 07:27:42 PM »
Hi Oliver,

I totally agree with you, I am an expert in digital cartography and photogrammetry with 15 years experience. It turns out that today, many people believe that generate digital cartography is something light, without any kind of professional training can go with your camera phone and generate cartographic models. In my country I see as unfair competition is presented, where all appeared says it can generate maps with a camera attached to a bird and offers services like a cartography company.

And the saddest thing is that most people do not have any kind of professional training in photogrammetry.

Best Regards,

Diego

Wishgranter

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Re: aerial photography?
« Reply #18 on: May 03, 2012, 08:22:22 PM »
Think on this: Photoscan is a GREAT tool, when you know what to do, how to prepare data, then output is excelent.

 As Oli63 and Diego wrote, is not for playing with it without a lot of knowlege and experience..... If it was so easy then services in this area would cost not so much......

Oli thanx for sharing deeper info..
 
Sigma as im wrote earlier, you can learn a LOT from profesional like Oli for your career if want grow in this area..
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fpbv

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Re: aerial photography?
« Reply #19 on: May 03, 2012, 10:48:20 PM »
Oli63 and Diego

You are all right!
Here in Brazil the game is way unfair too.
Unfortunaly there?s a lot people doing "mapping/cartography" without knowledge.
Myself thought to give up to working in this area but I decide to not do since I discover some new technologies like PhotoScan.
I hope the future will be bright for us professionals because the competition is really not fair.

Oli63

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Re: aerial photography?
« Reply #20 on: May 04, 2012, 12:52:42 AM »
Well, life is unfair. But not always to your disadvantage. ;-)
Isn't being more innovative, quicker, smarter, more effective.... than others the really interesting thing in life?
Give others the chance to do it the wrong way too!
« Last Edit: May 04, 2012, 12:55:04 AM by Oli63 »
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tezen

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Re: aerial photography?
« Reply #21 on: May 04, 2012, 11:52:09 AM »
Hello!

Sigma wrote that he wants to generate a model of a 1km*2km valley with allmost 5m precision.
I think that and even better solution (1m) could be done.

@Wishgranter:
Yes - professional Quadrocopters are at another pricerange (~10000).
If you once handle a RC-helicopter an RC-Quadrocopter isn?t a big challenge to fly with.
The battery-cost is low if you compare it to helium/baloongas used on balloon/blimbs.
Take a look at the DJI Hexacopter Flamewheel 550 on the net and videoportals.
I`ll use it mainly for shooting Videos - for sure testing it with PhotoScan.

@Oli63:
1. There are some solutions using GPS.
2. Point 1...
3. A remote-controlled Cam will work. In continuous fireing mode you could select the best shots.
4. The DJI Flamewheel 550 (Hexacopter) could take up to 1kg.
5. You?ve to do the same things even on the ground.
6. Yes.
7. I`ve heard that there could be much problems in germany (except bavaria).
8. Point 1...
9. - 30. ... :D
Experts/professionals with lots of experience in cartography and photogrammetry will do the job better for sure. This summer I?ll show my results on this forum and then everybody will see if I was going the wrong way!

@diegotorres:
Don?t know to who you?re talking to (Sigma or me?). Your joke is OK if it?s sick attaching a Remote-controlled DSLR (16Mp) via gimbal to a Hexacopter. Btw: I`ll use the results for artistic purposes and not for exact cartography with the precision of two inches in an area roundabout 1km*2km...

Greetings
tezen

sigma

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Re: aerial photography?
« Reply #22 on: May 07, 2012, 08:23:24 PM »
well, I took some pictures of a section of the valley over the weekend, and the results are good but not great. I would tend to agree that aerial photography would improve things quite a bit. So I will get a plane/copter to do a flyover with a good camera.

You are inferring that a plane might be more appropriate that a copter. Am I reading this right?

I also noticed that tagging each photo with coordinates improves things quite a bit, so I am on the market for a good UAV with GPS and ability to mount a good camera on it. I'll be going through forums to get recommendations for such a setup, but I'm also open to suggestions: please let me know what you are having success with along with lessons learnt.
Thanks again!

Wishgranter

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Re: aerial photography?
« Reply #23 on: May 07, 2012, 09:14:47 PM »
see PM......
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andyroo

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Re: aerial photography?
« Reply #24 on: May 07, 2012, 10:05:05 PM »
Hi sigma,

I am getting good results - much better than 5 m resolution - using a canon D10 ($250) bolted to the flightstep of a Cessna 172 with $50 worth of ram mounts (B-231ZU base, short arm, 1" ball).

I used CHDK to boot a modified firmware for the camera and run a 3 second intervalometer script I wrote, with shutter speed of 1/1500s and the neutral density filter forced off.

Using Photoscan Pro I am able to generate good quality DSMs and orthos, just by setting the ground plane with coordinates georeferenced from best available data that I can ID on the photos. I am using some LiDAR to get the z values, and 6" aerial imagery from bing maps to get the xy. The DSMs need some cleaning (I have lots of noise where the water is), but that might be better done in CAD or using meshlab, or something like that.

JC

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Re: aerial photography?
« Reply #25 on: May 08, 2012, 02:53:26 AM »