GoPro with modified lens for high accuracy DEM

[MiguelVarela]

Hi,

For my project I need to "see" the elevation of a beach to an accuracy of 10cms or less.
Since I don't have much money for this, I was thinking about buying the Phantom 2 and GoPro with Gimbal, PFV and pre set flight patern since this is a cheap all in one setup.

Then I saw that the GoPro is an issue because of the too wide angle lens and the rolling shutter, so I tried to find another solution until I saw this tread by Porly:
http://www.agisoft.com/forum/index.php?topic=2480.0

He says that with a modified lens to 60ª he saw no difference from a professional setup, except the quality of the orthophoto, but that the cloud point was no different.

Anyone has good experiences with a modified GOPro for accurate height calculations?

Cheers

[GPC]

A decimeter is going to be difficult no matter how you cut it.. how are you going to establish GCP that accurate on a low budget?

The issue with gopro has to do with the fisheye lens.. you defish the images and they work fine.

[MiguelVarela]

Hi Cs,

For the GCpoints I'm thinking of setting a few 1m sticks vertically on the sand across the beach and use them as gcp since I know their exact height. Would you think this would work?

Is there another way of getting an accurate elevation without using any expensive survey equipment like a Differential GPS?

About the GoPro, from what I read here on the forum, the issue is not only the lens "defishing" but the rolling shutter...

[GPC]

Unless I'm misunderstanding, your GCP idea is not going to work.. in fact, I can't think of any way that it would work and I've been to photo control for nearly 20 years. You need to know the measurements between the GCPs, absolute distance between each other.. setting 1m rods apart from each other will tell you nothing about their locations.

I've used a gopro and it works fine... I know some people say it doesn't but trust, it does.

Attached image was done with gopro after defishing it.

[MiguelVarela]

Hi CS,

Thanks for your reply!

So If I set a few GCP's and I know their exact measures between them, could that work as a way to get a greater accuracy?

I'll look into the GoPro once more then... thanks!