Messages

16

General / Re: Dam in 3D - Mixing horizontal pictures and vertical

« on: June 02, 2014, 04:24:14 PM »

I would recommend one set of imagery taken with nadir dircetion and two other sets wit a 60 and 45 or 30 degreee camera tilt. Additionally photos from the ground. Then you'll have enough tie points for a correct photo alignment.

17

General / Re: Aerial imagery 'holes' in multiple data sets

« on: May 31, 2014, 11:08:37 AM »

Hello,

obviously, the wrong image matching results from a poor overlap. I recommend strongly to use at least 70 to 75 % . However, above Vegetaion even 80% will not be enough, because of object movements and a low contrast / dark regions with iso noise etc. If you have more matches in NIR than in VIS, this is a strong hint to problems with vegetation since vegetation shows much more contrast in NIR imagery.

I'm just testing 90% Overlap, will post here the next days.

regards
Ansgar

18

General / Re: Tetracam multispectral imagery processing

« on: June 05, 2013, 09:02:03 AM »

Hi everyone,

longtime reader, first time poster...

Ricardo, I'm sorry, but I think, you can forget the Tetracam. This camera has an extreme rolling shutter, see attachment of this post. Unfortunately, two years ago, I also trapped on the product description and bought an ADC. This camera is useless in ANY moving camera platform. This means, you'll never ever get undistorted images putting the camera in a UAV (Copter) or even in shaky hands. You can produce the effekt on your own: Just take the camera in your hands and shake it during the exposure...

Ok, there might be one case, where you might get some results that "might look promising":
Mounting the Tetracam in a fixed wing aircraft, which is moving fast forward. Then, you'll also get distorted images, but maybe, with individual camera calibration option in PS, you can "fix" this.

But, the plane WILL roll during exposure, so you'll never get correct results, only results that "might look correct".

In my humble opinion: ADC Tetracam is rubbish. I tried to return it to my vendor, they neglected.