Areal Photogrammetry with Sony Nex7

[jtuhtan]

We generally try to keep ISO as low as possible (<800) and use manual settings (focus at infinity, shutter speed 1/800 or less, f 6 or less) to fix all imagery.

For evening or low-light imagery, you can use Auto ISO as it does a pretty good job across all images.

For really noisy images, i've tried Topaz DeNoise, it works pretty well:
http://www.topazlabs.com/denoise

We also tried using the Sigma 60mm, but found the rolling shutter problem caused blurry subregions in many of the images. Right now we use the Sigma 30 and 19mm at a height of 20-100m, depending on the application.
 

[Cavi_Ing]

Hi Jeff,

Yes, I am very interested in the BSC Thesis. Please send it to "arptho@bluewin.ch"

Thx

[b3059651]

Hi all,
The information you provide is really useful. I would like to ask how do you test what settings are the best without flying, just checking if the image looks good?
Do you check if the edges are sharp?
I am thinking to do something similar to find the optimal settings for Sony A6000 with 16mm pancake and 20mm. The UAV is flying max. 120m above the ground and is a fixed wing. I was thinking to just replicate the distance, set a black and white target at a 120m distance and capture it with different settings, especially to check the optimal aperture for focusing to infinity at 120m.

It would be good to look on the thesis you recommend. I am based in Newcastle University and I have many Germans who can help me retrieve some results. Is it possible to send a link of the thesis?

Thanks,
Regards,

[Mdaemon]

We typically use a NEX-6 with a Sigma 30mm F2.8 and are generally satisfied. We also use the time lapse app to set the image intervals, you can download it here:

https://www.playmemoriescameraapps.com/portal/

If you speak German, I can send you a recent B.Sc. thesis we supervised where the optical properties and camera settings of various setups were tested. Might be interesting for you.

Jeff

@Jeff: you use the time lapse and get fotos out. does it work well? this would give me the option to refrain from using the infrared shutter cable, which is still a possible mistake in the flight.
i am using a microkopter oktokopter for surveying purpose.
regards
martin

[mobilexcopter]

NEX 6 has a multiport connector ( like A5000, ... ) which can be used to trigger the camera via MK's transistor output or a servo pulse if combined with right trigger device. 

[Mdaemon]

yes, I know it and I have used it. geometry of gimbal, connector at side of camera together is bullshit and does not work, if you want to make fotos from the uav.
IR can be a solution, but for my purpose the camera with the app making fotos every 2 seconds is a nice and cheap option.
regards
Martin

[mobilexcopter]

yes, I know it and I have used it. geometry of gimbal, connector at side of camera together is bullshit and does not work, if you want to make fotos from the uav.
IR can be a solution, but for my purpose the camera with the app making fotos every 2 seconds is a nice and cheap option.
regards
Martin

Sony direct triggering via multiport does work. It works via servo type relay trigger or MK's transistor output and is no "bullshit" as I and several of our customers are using it. From the UAV's... 

But you are correct, the timelapse app is a cheap solution.

[Mdaemon]

the system works with the trigger, but: you have to place it on the left side of the camera. as you do so, it is not possible to move the camera in a 90 degrees down position, as the cable is blocked at the side with the gimbal and the system will not work.
so use different  gimbal, use a different camera or use a different trigger system.
all itself is ok, but the combination is bullshit.

regards
Martin

[Mdaemon]

See the pic, it clearifies.
Martin

[mobilexcopter]

Yes, I see your problem now. But the problem can be avoided with a different multiport cable and a small shift of the camera to the right as the lens is on the left side of the camera and you should keep your sistem in balance.

Many users have different gimbals, not the MK's SLR2, or even fixed camera setup on the planes, so the triggering solution is good, especailly because you can control the manner of triggering via remote ( in case of MK usage - off, by distance or manual ).

I attached a picture of a custom multiport connector housing. 

Best regards,

Alex

[Mdaemon]

yes, Alex, I have tried to get one of these. Unfortunately they are not available at MK.
Assembling one myself was not the solution, I am more the User not the Builder.

but having now the IR is ok and for surveying I can use also the program trigger.
I will contact you directly via your HP.

Martin

[Darko]

Hi Martin,

I am in the same bussines as you are and my first multirotor was MK with the Sony NEX5 camera. I was uinsg GentLed IR time leapse trigger. It worked fine but the LED position was the problem and sometimes in failed to work. The final solution was the small part of the duck tape that was used as a reflector for the IR signal, Time leapse is a good solution since you are flying with the constant speed it is easy to calculate the time constant for the good overlap of the photos.

I am interested in sharing my expirience with you and other guys, but more on the surveying side. Maybe we should form some kind of SUERVEYORS board of this forum.

Best regards,
Darko Car

[Mdaemon]

Hi Darko,

thanks for your reply. I made a flight today and used the App called "Zeitraffer" direct from the Sony Alpha 6000. It costs 10 € and allows to make up to 990 Fotos with a fixed interval. Today I was using 2 s, means at least 300 Pics of a 10 Minutes flight. Seems to have good overlap as the height was 80 m (sometimes more) and the speed was only 3 m/s.

Surveyors board is good. I made also some postings at the mikrokopter forum. Which drone do you use? I use a Microkopter Oktokopter XL.

regards

Martin

[Darko]

Hi Martin,

I had the same MK before. It's history now since I've mixed something and it has finished it's life on my celing. I am happy it didn't catch me since it was the full throtle take off from my desk in the office. Anyway, I have decided to go on with other flying machine before that. The real trouble with the MK is the programable range of 250m.

I have made my own Hexa design. I did, design it for my needs and I am very happy with it. It is DJI Wookong M controler with 1W 900MHz data link, 6 T-Motor 3506 motors wit 12*4 T-Motor carbon props. It works perfectly. I have 4S - 10 A and 16 A batteries and with 10A I can fly for 22min, with the 16A it can stay in the air for 30min. Of course, I never use more than 70% of the power.  My regular flying speed is 12m/s and with tone flight I can cower about 150-200 ha. I have 5 batteries. I am usually flying up to 3km away from my takeoff site.

As a sensor I am using Samsung NEX 1000 with it's original 20-50 lens which is the discovery since it is the clearest lens I've ever tried. 

Let's start with the Surveyors board these days, OK?

Best regards,
Darko Car

[Mdaemon]

Yes ok,

Greets Martin