How to obtain the focal length from ocam_model??

[chan...@gmail.com]

Dear prof. Davide:

Thank you for your response, again.

One question we met as follows.

How to obtain the "focal length" of camera from ocam_model in your release toolbox ??

Thank you.

[Davide Scaramuzza]

Hi,
You can't if the field of view of your camera is larger than 180 degrees
(it doesn't exist, since it would be negative).
I dont know what you need a focal length for, since you have the
world2cam and cam2world functions (which project image points on to the
unit sphere), but, to answer your question, the focal length is simply
equal to W/(2*tan(FOV/2)), where W is the width of the image and FOV is
the field of view of the camera in radians.

Best
Davide

___________________________________

Prof. Dr. Davide Scaramuzza
Head of the Robotics and Perception Group: http://rpg.ifi.uzh.ch
University of Zurich,
Andreasstrasse 15, AND 2.28, Zurich, Switzerland
Office: +41 44 635 2409
___________________________________

[Davide Scaramuzza]

Hi,
You can't if the field of view of your camera is larger than 180 degrees
(it doesn't exist, since it would be negative).
I dont know what you need a focal length for, since you have the
world2cam and cam2world functions (which project image points on to the
unit sphere), but, to answer your question, the focal length is simply
equal to W/(2*tan(FOV/2)), where W is the width of the image and FOV is
the field of view of the camera in radians.

Best
Davide

___________________________________

Prof. Dr. Davide Scaramuzza
Head of the Robotics and Perception Group: http://rpg.ifi.uzh.ch
University of Zurich,
Andreasstrasse 15, AND 2.28, Zurich, Switzerland
Office: +41 44 635 2409
___________________________________


On 11.12.2013 09:12, chan...@gmail.com wrote:

[chan...@gmail.com]

Dear Prof. Davide:
Thank you for your response, We want to obtain the focal length and use another calibration by prof.Higgins. This is his report"ENHANCEMENTS FOR DIGITAL
IMAGING OF GUSSET PLATE CONNECTIONS: FISHEYE AND IMAGE STITCHING" and use the calibration by matlab.
You can download and try it.
Thank you~~

chan...@gmail.com於 2013年12月11日星期三UTC+8下午4時12分03秒寫道： > Dear prof. Davide: Thank you for your response, again. One question we met as follows. How to obtain the "focal length" of camera from ocam_model in your release toolbox ?? Thank you.

[Davide Scaramuzza]

Hi

I already replied this question on the ocamcalib online forum. Please check there for the answer.
Best
Davide
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