Re: correlation of rotated image with perspective

On Jul 30, 8:05 pm, Bob <ralva...@xxxxxxxxxxx> wrote:
On Jul 30, 6:44 am, Adam Chapman





<adam.chap...@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hi,

I'm trying to make a vision-guided robot aircraft at uni and I want it
to land on an 'H' shaped marker on the ground. The aircraft will only
use the information from its mounted video camera to navigate.

I have been looking into ways of identifying the helipad seen in the
video, which will be rotated, scaled and have perspective. These
properties will be used to determine the orientation and 3d position
of the aircraft w.r.t. the landing marker.

The processing will need to be very fast, close to real-time.

I understand that the fourier-mellin transformation can be used for
identifying rotated objects, but I am not sure how robust it is for
perpective and scaling (zooming).

During my university career I have specialised mainly in aircraft
control systems and simulation programming. Image recognition and
processing is very new to me and I expect there are better ways to do
things than those methods I know of.

If anyone out there could throw some suggestions my way, I would
really appreciate it.

Regards,
Adam

This is quite a difficult project to do with image recognition
techniques. I am an imaging guy so other fields always seem easier :-)
but have you considered using a GPS sensor? Another possibility is to
put an active beacon on your target such as from a narrow band optical
source (like a laser or LED) and then use an optical filter in front
of a camera. Your image processing would then just involve
thresholding. Another idea would be to have a light source on your
aircraft and a reflector at your target like the mirror balls they
used to have in dance rooms. You could again use optical filtering to
reduce background.

Good luck and let us know what works.

Bob- Hide quoted text -

- Show quoted text -




Thanks for the reply Bob,

This visual system is designed to go on a military UAV in urban
environments, so anything that lights up will likely be shot at!
I think that a rotated 'H' could be identified usin a foruier-mellin
transform, but it's the distortion from perspective thats really
confusing me.

.

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