[PD] fish eye camera distortion correction

[Csaba Láng]

I am getting closer to the solution, however have a bigger problem than
expected.
As the camera is pointing at the projection surface, I have the classical
video feedback effect. As a result, the corrected image is getting bigger
and bigger, and I loose more of the image,
than the fish eye correction was made with the [curve3d].
how could I move the image after gemframebuffer and move back with the
offset of the pix_snap?
Or what for the offset is made?
Is there any method to avoid the video feedback in pix_buffer?
Looking forward to any brilliant idea :)

Popesz

On Wed, Jul 17, 2019 at 10:00 PM Christof Ressi <christof.ressi at gmx.at>
wrote:

> Personally, I would always prefer a fragment shader over fiddling with
> curve3d in GEM :-) This is probably what you want:
> https://www.geeks3d.com/20140213/glsl-shader-library-fish-eye-and-dome-and-barrel-distortion-post-processing-filters/5/
>
> It might need some modification depending on the kind of texture and GLSL
> version your using.
>
> Christof
>
>
> *Gesendet:* Mittwoch, 17. Juli 2019 um 21:27 Uhr
> *Von:* "Csaba Láng" <langcsaba at gmail.com>
> *An:* pd-list at lists.iem.at
> *Betreff:* Re: [PD] fish eye camera distortion correction
> Thanks for the ideas.
> Luckily I will snap the pix just once a second or two. Hope the processor
> can handle it.
> Which correction is easier, curve3d or the shader?
>
> On Wed, 17 Jul 2019 at 21:04, Jack <jack at rybn.org> wrote:
>
>> Sure, use a framebuffer with [gemframebuffer] to capture offscreen your
>> scene.
>> The problem is to send back your texture produce by [gemframebuffer] in
>> pix_ domain to use [pix_movement] and [pix_multiblob], fortunately there
>> is [pix_snap] for this (this process is quite slow, it depends on your
>> hardware).
>> Look at :
>> Help => Gem => examples => 04.pix/ => 26.framebuffer_readback.pd
>> to see how to use it.
>>
>> A note, instead off [curve3d] it is also possible to use shaders (on
>> fragment) to do the correction of the lens distorsion.
>> ++
>>
>> Jack
>>
>>
>>
>> Le 17/07/2019 à 20:36, Csaba Láng a écrit :
>> > Looks good, but now a bigger problem came up.
>> >
>> > My aim is to correct the fish eye distortion for pix_movement and
>> > pix_multiblob analyses.
>> > Which means first I have to make the curve3d correction and then use
>> > those pixels in pix_multiblob.
>> > Is it possible?
>> >
>> > On Wed, Jul 17, 2019 at 8:16 PM Johnny Mauser
>> > <joson.android at googlemail.com <mailto:joson.android at googlemail.com>>
>> wrote:
>> >
>> >     Maybe gems [curve3d]?
>> >
>> >     Csaba Láng <langcsaba at gmail.com <mailto:langcsaba at gmail.com>>
>> >     schrieb am Mi., 17. Juli 2019, 20:10:
>> >
>> >         Hi list,
>> >         is there an easy way to correct fish eye camera image
>> distortion?
>> >         I think if a vortex kind of tool.
>> >         Best,
>> >         Popesz
>> >         _______________________________________________
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