Aerial Photogrammetry Phantom 2

[igor73]

Hi,

Have anyone tried aerial photogrammetry with the Phanom 2 Vision + drone?  It has a 14mpix camera and can shoot RAW.  Anyone   have experience with it? 

http://www.dji.com/product/phantom-2-vision-plus

[ozbigben]

At the end of the day the critical thing is the camera, the details of which are a bit sketchy as there are no specs on the lens.  The intro video mentions 3 fov settings so I'd suspect that they're just crops of the full ultra-wide image. If that is the case you could be down to 6mp by the time you get to the "narrow" fov. It would be nice if they provided some samples of raw images.

[andyroo]

From the specs at B&H it looks like it's a GoPro-like camera, which means it probably has pretty bad rolling shutter. I know folks who have tried with GoPro and not good results. I tried some reconstruction with a stablized cineflex and also didn't have much luck. I think that rolling shutter is a killer. Many more posts to that effect around here somewhere. But you could always stick a $60 canon A2200 on it with CHDK...

--Edit for clarification: The GoPro issues I am familiar with are more related to creation of the surface model than reconstruction of an orthophoto - thanks SAV for bringing up that point - GoPro's can make imagery that is perfectly functional.

[SAV]

I had also an eye on the Phantom 2 Vision+
The specs of the camera seem alright:
- 14 MP (4384 x 3288)
- focal length 5mm
- sensor size 1/2.3" = 6.17mm x 4.55mm
- Shoots RAW (DNG, which might help to squeeze more out of your images, especially if you have pictures with a high dynamic range)
- App which controls the camera has timelapse/intervalometer function

Some people (including myself) already used pictures from a GoPro (attached to a UAV). The GoPro is definitely not the first choice for photogrammetry, but the results are quite good.

You can even change the lens of the GoPro to a 60 deg lens which will give you a focal length of 5.5mm (at around 10 Megapixel). User Porly states that dense point clouds he gets from the (modified) GoPro are as good as from a Sony Nex 5 (more Details http://www.agisoft.ru/forum/index.php?topic=2480.0). 

So I think that the Phantom 2 Vision+ with it's 5mm focal length should be a good choice. Still waiting for someone to buy it and test it first 

Cheers
SAV

[igor73]

I will have the opportunity to borrow a phantom 2 vision + soon.  Will let you know how it worked. 

[DevDoctor]

I use a PV2 (+ came out shortly after.. upset about that) and it works with photoscan but the results can be a little noisy. I go about 6mph and it seems fine. I am mostly just testing it right now and spend more time just flying it around and crashing it than anything.

The camera has some terrible, terrible noise patterns. Sort of a cross hatch look.. must be the way the are compressing the photos or something. I haven't seen anything like it. There is a raw shooting mode but it doesnt work with the intervalometer.

If I was going to do it again.. I may just get something with a better camera.. but the live video feed back is great.

Also, I think a groundstation setup can be purchased for the PV2 so you can plot a route and have it do the collection outside of the transmitter's range.

[SAV]

Hi DevDoctor,

Update your Phantom 2 Vision's app on your phone, and you will get waypoint functionality for free. Was released yesterday by DJI.
But update your cameras and quadcopter's firmware first, before you update the app. The new camera firmware should improve your DNG files. Maybe now the intervalometer works.
Could you check if it works after the update? Also could you check the minimal interval you can choose inside the app? Is it really 3 seconds?

Would be great if you could share a few raw files to see what results one gets in photoscan. Thanks.

Cheers
SAV

[jquiroga]

Hi,
  I make some test with Phantom 2 Vision+, intervalometer works at 3 secs but really I can't get result from Photoscan. Photos didn't align well, like len distortion affect the process.
  You can download an example (10 photos) taken between 3 secs at 30 meters of altitude. Please take a look and if you can make mosaic on photoscan share steeps with me.

https://www.dropbox.com/s/om4wicxd8l64agk/Photos_P2VPlus.rar

Regards,
Javier

[RHenriques]

Hi jquiroga

Your photos do not have much overlap. You have to guarantee, at least, 60% of overlapping between consecutive photos. Try to fly higher (more than 70 meters -better) or reduce the intervalometer times (not as recommended as an increase in height). Your images are also from a very complex set of features, with trees and houses which are to much "detached" from the dominant topographic surface (ground). This creates lots of problems of occlusion. At a height of 30m, it's almost impossible to have a good matching in your pictures. To be successful, try to fly, at least, above 70 or 80 metres and increase the overlap. I've made some images with the gopro 2, which had a huge fisheye distortion, and I was able to obtain a valid 3d model from a landslide.

Cheers   

[jquiroga]

Thanks for your reply, i will made same test at 70mts, intervalometer at 3segs and comment The final result.

Best regards!
Javier

[hzmarrou]

Hello Javier @ jquiroga
 Could you please post some 70m photos when you make them?
Thanx

[jquiroga]

Hi!
   Finally I could make the model with my phantom 2 vision+, flying at 70 meters / intervalometer at 3 secs / 14mpx resolution. Take a look at the attached picture.
   I be wanting to know how to change the FOV of the camera, from 110 ° to 85 °, for best results.

Regards,
Javier

[RHenriques]

Hi jquiroga

That's a lot better! Do not have the temptation of flying too low. For better results you must always fly around 70 metres or higher. You will avoid occlusion and tangential deformation. Get a kit to reduce the FOV of the gopro for better results. 85? it's fine. If you search in google, you will find lot's of kits to do that modification. Never forget to guarantee that you have a 60/70 % overlap, in both y and x direction, between consecutive photos. If you reduce the FOV you can need to increase the number of photos by reducing the shutter interval to get the needed overlap.
Cheers

[mrb]

I've been using the phantom 2 + GoPro for the past 3 months, doing aerial photogrammetry of landscapes and objects/buildings.  It's working great so far.

[hzmarrou]

Hi mrb,
Could you please send some sample photos as well as an orthomosaic if you have that?
my email adsress is hzmarrou at gmail