Do you agree with my definition or not? And which code are you referring to - the master branch or my patches?
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".
