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  1. #1
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    Realistic Camera

    Hi,

    This project has been made by Don Fussell for PBRT
    (Physically-based Ray Tracer):
    http://www.cs.utexas.edu/users/fusse...signment3.html

    May be this should take a lot of rendering time in LW?
    ...Not easy to build virtual parametric lens-shape,
    and calculate ray intersection, refraction...

    Preview of an utopic camera plugin (it works only as a LensViewer yet):
    Attachment 34013

    Sample comes from "Modern Lens Design" which is an expansive book,
    with ascii lens specification tables.

    Denis.

  2. #2
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    Hi,

    really interesting. And I like a lot how elegant and simple s your proposal for the plugin.

    Maybe something like this would be really useful for arch viz and photographers as well.

    Best regards,
    David

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    And matching real cinematographic footages...!?

    Denis.

  4. #4
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    In another hand, if we don't want to simulate
    chromatic aberrations or dof,
    There are calibration softwares which can measure distorsions,
    Attachment 34022


    Then building a deformed plane in Modeler,
    a job for "Mesh UV smooth" option in Advanced Camera ?

    Denis.

  5. #5
    I think it could be really interesting, even if adding heaviness to the already slow LW engine looks odd.
    Beside LW's limitatons, it's an elegant and useful tool; it would be a really nice add-on if it works with Kray or Fprime.
    Just an hint and a hope, kudos for all your work btw

    Paolo

  6. #6

  7. #7
    LightWave Engineer Jarno's Avatar
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    Adding realistic camera models to ACT is high on the list of things to do. I am well acquainted with the works that dpont references.

    ---JvdL---

  8. #8
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    To complete previous calibration chart, tangentielle is V axis
    and sagittale is U axis.

    Sorry, if you think that some part of this thread
    are too much esoterical or SDK relative, but I hope
    we can do more accurate experiments with
    "Advanced Camera" that only funny demos :-) and
    psychedelic samples.

    About "Realistic Camera" port,
    not sure, to go far from single lens-viewer I have made,
    original source takes shape from "pbrt" core,
    (disk shape is pure "pbrt" function & lenscomponent from "RC" plugin).
    To ask for intersection ray and to calculate normal
    on lenscomponent' intersection point,
    may be we need build our own ray-marcher function
    for implicit surface in LW?

    Don't know if fpx & fpy in Camera Handler
    are correct input data for "pbrt" ConcentricSampleDisk
    function as lensU and lensV.

    Have not revised my optical knowledges since
    I have left my school (a long time ago),
    remember only a few things
    about principal and focal points for a lens stack.

    PS: Jarno, why hither and yon have been removed
    from SDK? I Know there are still present...

    Denis.

  9. #9
    LightWave Engineer Jarno's Avatar
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    Quote Originally Posted by dpont
    Jarno, why hither and yon have been removed
    from SDK? I Know there are still present...
    Because it proved to be too bothersome for an ACT plugin to come up with a hither and yon distance that always worked consistently with the other things in Layout. So now Layout modifies the projection matrix returned by the ACT plugin to have the correct hither and yon distances.

    ---JvdL---

  10. #10
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    All pages below are french but there are some nice java applets
    to demonstrate some optical basics:

    http://www.univ-lemans.fr/enseigneme...eo/rayons.html
    (move yellow point to vary ray incidence)
    http://www.univ-lemans.fr/enseigneme.../aberchro.html
    (vary R, Y, B)
    http://www.univ-lemans.fr/enseigneme...igeo/zoom.html
    (move L2 and keyboard arrows to focus)
    ...

    Denis.

  11. #11
    now here's a "banality"... Maxwell's renderings have all a strong luminosity-contrast ramp from the center to the corners. Though it is not always a desiderable effect, it often gives a good depth and a "mod" to the pic.
    Beside the fact it's doable in PS, is it a reproducible effect with ACT ?

    Paolo

  12. #12
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    Have not tested Maxwell, not seen this effect,
    just found the "Simple Filter" in ACT and his associated
    Texture panel, it has specific gradients for pixel
    position such as "Radial Film Position", and you can
    use classic "Blending Mode" popchoice for layers,
    with "Mixing Filter" mode you can have
    separate color filter effect.

    May be this is the vignetting effect
    http://www.vanwalree.com/optics/vignetting.html
    (common aberration or stylistic effect)

    But no luminosity-constrast effect, because Texture can't
    have access and modify sampling data (ray value), you can
    add, substract... texture layers.

    Those modifications could be made with an Image Filter plugin,
    vignetting or some other things,
    you could add The Virtual Darkroom for lw,
    or a desaturation depth effect for color, or external post-rendering
    effect (not exhaustive).

    Denis.

  13. #13
    hmmm it looks like it's just that vignette effect.
    Never used Virtual Darkroom myself... if it is cabable of this ill try, maybe in post (render in fprime/Kray, then import image sequence and apply filters).
    Maybe i could get it witha simple gradient too, applied to all surfaces and referencing a Null parented to Camera...

    Paolo

  14. #14
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    So we can ignore hither and yon in projection preview,
    confirmed with a working clone camera plugin of perspective camera.

    I forgot to credit Nicolas Galoppo Von Borries,
    Alan Jao, Murad Akhter and may be some other persons
    in "Realistic Camera" or "Camera Simulator" project.

    Here I have posted two samples illustrating uniformly sampled rays
    coming from film in the direction of the back lens component and intersecting/refracting with each lenscomponent.
    [ATTACH]Attachment 34124[/ATTACH]


    Denis.

  15. #15
    apart from being first Sigr Ros's album, what is Yon - and hither too, in simple words ?

    Paolo

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