[Bf-committers] GSoC 2017: Camera breathing support

Tianwei Shen shentianweipku at gmail.com
Fri Mar 24 16:27:50 CET 2017

Hi Levon,

Thank you so much this long reply. First of all, I’ve been looking for user tests and suggestions for the multi-view reconstruction project. If you have ideas for making it better, just feel free to drop me emails. On the other hand, it is still a quite large patch. So we need time to split it up and gradually merge it into the master. But hopefully this can be integrated well with the camera breathing support project and even automatic tracking in the future.

As for the camera breathing support, I didn’t realize lens distortion parameters would also change with the focal lengths. I thought we’d only deal with changing focal lengths with the zoom-in/out motions. So things become complicated here since it seems to me that focal lengths and distortion parameters cannot be estimated on the fly. Users have to first calculate this information (focal lengths for each frames and their corresponding lens distortion parameters) using some calibration tools. Can the solver reliably deal with changing focal lengths and distortions? On the other hand, if users have to first calculate focal distances using some tools (if Blender doesn’t have its own) in the first place, would it impose burden and inconvenience for users? 


> On Mar 24, 2017, at 8:57 PM, Levon <levonh at gmail.com> wrote:
>> Message: 1
>> Date: Fri, 24 Mar 2017 02:26:38 +0800
>> From: Tianwei Shen <shentianweipku at gmail.com <mailto:shentianweipku at gmail.com>>
>> Subject: [Bf-committers] GSoC 2017: Camera breathing support
>> To: bf-blender developers <bf-committers at blender.org <mailto:bf-committers at blender.org>>
>> Message-ID: <3B4BA086-116B-417D-A288-C8F1CA7A880F at gmail.com <mailto:3B4BA086-116B-417D-A288-C8F1CA7A880F at gmail.com>>
>> Content-Type: text/plain;       charset=us-ascii
>> Hi Everyone,
>> Last summer I participated in GSoC 2016 and worked on the multi-view
>> camera reconstruction project. Some of my efforts are summarized in this
>> blog: http://hlzz.github.io/blender3/ <http://hlzz.github.io/blender3/> <http://hlzz.github.io/blender3/ <http://hlzz.github.io/blender3/>>.
>> And this patch (https://developer.blender.org/D2187 <https://developer.blender.org/D2187> <
>> https://developer.blender.org/D2187 <https://developer.blender.org/D2187>>) is now being reviewed and revised.
>> This year I would like to apply again and work on the camera breathing
>> support, which is already requested by some users during the time I worked
>> on the motion tracking project. Now I need clarifications for some specific
>> problems.
>> 1. should we automatic detect the changes of focal lengths, or is it
>> specified by users as additional inputs (like the focal length for each
>> frame)? I know we can read exif tags to get focal lengths for photos. Do we
>> have a similar approach for videos?
>> 2. Is the current UI able to handle camera breathing, if we need
>> additional inputs from users?
>> I think this project also has something to do with my revisions done on
>> the motion tracking system last summer. Hopefully I should be able to merge
>> the revisions and move towards the goal of automatic tracking.
>> Thanks,
>> Tianwei

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