On Mon, Mar 22, 2021 at 1:35 PM Daniel Playfair Cal < daniel.playfair....@gmail.com> wrote:
> > I disagree, if I use 180 hfov and 180 vfov it should not have extra > areas but only half of previous input. > > Not sure I follow - the ih_fov and vh_fov refer to the input (i.e. the > fisheye image). If you wanted to restrict the FoV of the output, surely the > way to do that would be to implement and use the FoV settings for the > equirectangular projection?. It doesn't seem right that the code for the > input projection is responsible for deciding what appears in the output. My > understanding was that the FoV settings simply describe the focal length of > the input or output camera so that points in the images can me mapped > to/from 3d coordinates. > > Take any equirectangular input and convert it to fisheye and than back to equirectangular. Or just take pure fisheye input with 180 h & v fov and convert it to equirectangular. There is plenty of such video content on esa website. To give you an idea of what I am trying to fix, here is an example input: > https://photos.app.goo.gl/o51NfY6aqWn3unPG6 > This is a 1920x1440 image taken on a GoPro Hero 5 black with the 4:3 Wide > FoV setting and stabilisation disabled. > > That is flat take of something else. Not real fisheye input. > The following filtergraph demonstrates the issues: > 'v360=input=fisheye:ih_fov=116.66:iv_fov=87.50:output=flat:d_fov=145.8' > 1. the dfov_from_hfov issue is worked around by the use of ih_fov and > iv_fov instead of id_fov, although you can try with id_fov=145.8 to see > that problem too > 2. by default the output has double the aspect ratio of the input, even > though the fisheye -> rectilinear transformation doesn't change the aspect > ratio (assuming the entire input image is included as it is in this example) > 3. much of the input is not visible in the output even though there is a > mapping between the chosen projections (changed in the visibility test > patch) > > 3 in particular I don't think can be solved by changing the settings - the > input field of view needs to match the FoV of the input camera, otherwise > the mapping is wrong. But it seems there is no other way to include the > entire input from a fisheye image. > > On Mon, Mar 22, 2021 at 5:59 PM Paul B Mahol <one...@gmail.com> wrote: > >> >> >> On Mon, Mar 22, 2021 at 5:09 AM Daniel Playfair Cal < >> daniel.playfair....@gmail.com> wrote: >> >>> I've tried that filtergraph and a few other similar ones and I'm not >>> sure what you mean - what exactly is the regression? >>> >>> I tried it on this image with an equirectangular projection: >>> https://wiki.panotools.org/images/0/01/Big_ben_equirectangular.jpg >>> >>> The only difference I can see is that there are less unmapped areas in >>> the output with the patches, because the final mapping from the output >>> equirectangular image to the intermediate fisheye image no longer fails to >>> map some areas which are present in the fisheye image. I would describe >>> this as an improvement? >>> >> >> I disagree, if I use 180 hfov and 180 vfov it should not have extra areas >> but only half of previous input. >> >> >>> >>> On Mon, Mar 22, 2021 at 3:30 AM Paul B Mahol <one...@gmail.com> wrote: >>> >>>> Sorry, but I cannot apply this set as is, It makes at least one serious >>>> regression. >>>> >>>> For example try this filtergraph: >>>> >>>> >>>> v360=input=e:output=fisheye:h_fov=180:v_fov=180,v360=input=fisheye:output=e:ih_fov=180:iv_fov=180 >>>> >>>> On Sun, Mar 21, 2021 at 1:45 PM Daniel Playfair Cal < >>>> daniel.playfair....@gmail.com> wrote: >>>> >>>>> This changes the iflat_range and flat_range values for the fisheye >>>>> projection to match their meaning for the flat/rectilinear projection. >>>>> That is, the range is between the two x or two y coordinates of the >>>>> outermost points above/below or left/right of the center, in the >>>>> flat/rectilinear projection. >>>>> >>>>> Signed-off-by: Daniel Playfair Cal <daniel.playfair....@gmail.com> >>>>> --- >>>>> libavfilter/vf_v360.c | 19 +++++++++---------- >>>>> 1 file changed, 9 insertions(+), 10 deletions(-) >>>>> >>>>> diff --git a/libavfilter/vf_v360.c b/libavfilter/vf_v360.c >>>>> index 68bb2f7b0f..3158451963 100644 >>>>> --- a/libavfilter/vf_v360.c >>>>> +++ b/libavfilter/vf_v360.c >>>>> @@ -2807,9 +2807,8 @@ static int prepare_fisheye_out(AVFilterContext >>>>> *ctx) >>>>> { >>>>> V360Context *s = ctx->priv; >>>>> >>>>> - s->flat_range[0] = s->h_fov / 180.f; >>>>> - s->flat_range[1] = s->v_fov / 180.f; >>>>> - >>>>> + s->flat_range[0] = 0.5f * s->h_fov * M_PI / 180.f; >>>>> + s->flat_range[1] = 0.5f * s->v_fov * M_PI / 180.f; >>>>> return 0; >>>>> } >>>>> >>>>> @@ -2827,8 +2826,8 @@ static int fisheye_to_xyz(const V360Context *s, >>>>> int i, int j, int width, int height, >>>>> float *vec) >>>>> { >>>>> - const float uf = s->flat_range[0] * ((2.f * i) / width - 1.f); >>>>> - const float vf = s->flat_range[1] * ((2.f * j + 1.f) / height - >>>>> 1.f); >>>>> + const float uf = 2.f * s->flat_range[0] / M_PI * ((2.f * i) / >>>>> width - 1.f); >>>>> + const float vf = 2.f * s->flat_range[1] / M_PI * ((2.f * j + 1.f) >>>>> / height - 1.f); >>>>> >>>>> const float phi = atan2f(vf, uf); >>>>> const float theta = M_PI_2 * (1.f - hypotf(uf, vf)); >>>>> @@ -2858,8 +2857,8 @@ static int prepare_fisheye_in(AVFilterContext >>>>> *ctx) >>>>> { >>>>> V360Context *s = ctx->priv; >>>>> >>>>> - s->iflat_range[0] = s->ih_fov / 180.f; >>>>> - s->iflat_range[1] = s->iv_fov / 180.f; >>>>> + s->iflat_range[0] = 0.5f * s->ih_fov * M_PI / 180.f; >>>>> + s->iflat_range[1] = 0.5f * s->iv_fov * M_PI / 180.f; >>>>> >>>>> return 0; >>>>> } >>>>> @@ -2882,10 +2881,10 @@ static int xyz_to_fisheye(const V360Context *s, >>>>> { >>>>> const float h = hypotf(vec[0], vec[1]); >>>>> const float lh = h > 0.f ? h : 1.f; >>>>> - const float phi = atan2f(h, vec[2]) / M_PI; >>>>> + const float phi = atan2f(h, vec[2]); >>>>> >>>>> - float uf = vec[0] / lh * phi / s->iflat_range[0]; >>>>> - float vf = vec[1] / lh * phi / s->iflat_range[1]; >>>>> + float uf = 0.5f * vec[0] / lh * phi / s->iflat_range[0]; >>>>> + float vf = 0.5f * vec[1] / lh * phi / s->iflat_range[1]; >>>>> >>>>> const int visible = -0.5f < uf && uf < 0.5f && -0.5f < vf && vf < >>>>> 0.5f; >>>>> int ui, vi; >>>>> -- >>>>> 2.31.0 >>>>> >>>>> _______________________________________________ >>>>> ffmpeg-devel mailing list >>>>> ffmpeg-devel@ffmpeg.org >>>>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel >>>>> >>>>> To unsubscribe, visit link above, or email >>>>> ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". >>>> >>>> _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
