Gbaman
Posts: 120
Joined: Mon Jan 21, 2013 2:43 pm

Focal length and HFOV

Mon May 27, 2013 2:14 pm

I have been trying to stitch some photographs together taken with the raspberry pi camera board. The software (hugin) requires some lens data as the image does not have any stored with it. It needs
2 of these 3 values
Horizontal field of view (HFOV)
Focal length
Crop factor (aka focal length multiplier)

Anyone know at least 2 of the values? Without it, the software has to guess and it is having a hard time doing so.
Lead developer of PiNet, a free and opensource centralised user accounts and file storage system for Raspberry Pi classrooms used in over 200 schools across the world.
http://pinet.org.uk

amp88
Posts: 14
Joined: Fri May 18, 2012 2:00 am

Re: Focal length and HFOV

Mon May 27, 2013 2:29 pm

I don't think we currently know the precise focal length of the unit, but fastmapper estimated it at 3.6mm.
Crop factor should be ~9.44 (for a sensor size of 3.674 x 2.738mm, from the product specifications).

Good luck.

edit: improved focal length link

fastmapper
Posts: 27
Joined: Wed Mar 27, 2013 3:54 am

Re: Focal length and HFOV

Mon May 27, 2013 3:00 pm

Gbaman wrote:I have been trying to stitch some photographs together taken with the raspberry pi camera board. The software (hugin) requires some lens data as the image does not have any stored with it. It needs
2 of these 3 values
Horizontal field of view (HFOV)
Focal length
Crop factor (aka focal length multiplier)

Anyone know at least 2 of the values? Without it, the software has to guess and it is having a hard time doing so.
I took photos of a measuring tape to estimate a focal length of 3.60+/-0.01mm. For 2592 by 1944 pixel stills, this translates to a 53.50+/-0.13 degree horizontal field of view and a 41.41+/-0.11 degree vertical field of view.

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