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Author Topic: Appropriate focal lengths  (Read 3633 times)

ntriozzi

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Appropriate focal lengths
« on: August 25, 2014, 08:32:50 PM »
Hi,

New user here. I'm working with images taken at different focal lengths of a static subject. Perspectives are generally orthographic but also include skewed angles. Needless to say focal lengths range. Do I need to create  calibration 'files' for each focal length I am dealing with?

Also, what is the recommended number of images to use for creating calibration files? I've typically used four. Will that suffice for rendering 3-D meshes of subjects that cover an area of about 1-2 m?

Thank you for any replies!

Nick

Alexey Pasumansky

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Re: Appropriate focal lengths
« Reply #1 on: August 26, 2014, 01:20:34 PM »
Hello Nick,

If you wish to calibrate the camera, each focal length should be calibrated individually. But please note that while using zoom-lens it is almost impossible to set up exactly the same focal length twice. It is also recommended to keep the same focusing for calibration set as it was (or will be) used for shooting scenario.

As for the number of photos for calibration we suggest to make 5-12 images from different angles.
Best regards,
Alexey Pasumansky,
Agisoft LLC