On Tue, Mar 23, 2021 at 7:32 AM Daniel Playfair Cal < daniel.playfair....@gmail.com> wrote:
> Do you agree with my definition or not? And which code are you referring > to - the master branch or my patches? > Just do not introduce regressions into existing code. > > I'd like to get these patches to a point where they can be applied, but > it's going to be difficult if we can't agree on the goal. > > On Tue, Mar 23, 2021 at 5:15 PM Paul B Mahol <one...@gmail.com> wrote: > >> >> >> On Tue, Mar 23, 2021 at 5:00 AM Daniel Playfair Cal < >> daniel.playfair....@gmail.com> wrote: >> >>> What exactly is your definition of fisheye? >>> >> >> Take look at source code. I do not see how your definition matches one in >> source code. >> >> >>> >>> The definition I'm working with is the equidistant fisheye projection as >>> described here: https://wiki.panotools.org/Fisheye_Projection, i.e. r = >>> f * theta >>> >>> That mapping works for any theta, and you can have a circular image with >>> a field of view of up to 360 degrees before anything is repeated and the >>> inverse mapping is ambiguous. Hence my assumption that a rectangular output >>> image with a 180 horizontal/vertical field of view should still contain >>> areas near the corners where theta > 90 (because the diagonal FoV is > >>> 180), and these should still be mapped from such an image to a >>> equirectangular projection. >>> >>> Do you prefer for some reason to limit the fisheye projection to 180 >>> degrees on any axis, i.e. have the constraint that theta <= 90? If that's >>> the case I could patch xyz_to_fisheye and fisheye_to_xyz so that such areas >>> are marked as invisible? That causes your example filtergraph to work as >>> before. >>> >> >>> On Tue, Mar 23, 2021 at 3:46 AM Paul B Mahol <one...@gmail.com> wrote: >>> >>>> >>>> >>>> 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".
