[FFmpeg-user] V360 filter

[Paul B Mahol]

On 9/11/19, Michael Koch <astroelectronic at t-online.de> wrote:
> Am 11.09.2019 um 14:23 schrieb Michael Koch:
>> Am 11.09.2019 um 13:13 schrieb Michael Koch:
>>> Paul,
>>>
>>>>> I think the field of view isn't correct in the stereographic output.
>>>>>
>>>>> Here is a script for making really nice test images, for measuring
>>>>> field
>>>>> of view:
>>>> Well spotted, thanks, should be fixed.
>>>
>>> The field of view of the stereographic output isn't correct. Here are
>>> a few examples:
>>> set in command line / measured in output image
>>> 60° / 74°
>>> 120° / 135°
>>> 180° / 180°
>>> 240° / 212°
>>> 300° / 236°
>>> 360° / 274°
>>
>> Make this correction:
>>
>> new_fov = 180 * tan(fov/4)
>>
>> where fov the the field of view you get from the command line, and
>> fov_new is the value that you use for the filter.
>> You must exclude values too close to 360°, because 360° stereographic
>> projection is impossible.
>>
>
> P.S. of course fov must be converted to radians before using tan():
>
> new_fov = 180 * tan(fov * pi / 720)

Thanks, that cleared some stuff.
Should be fixed.

> Michael
>
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