[Sidefx-houdini-list] Camera model

Neil Scholes neil at uvfilms.co.uk
Thu Nov 29 08:26:08 EST 2012


Its just speed it up

im roting on warped plates - makes little difference if theres no 
projections

less conversions

Neil Scholes

www.uvfilms.co.uk
+44 (0) 7977 456 197

On 29/11/12 13:22, Colin Doncaster wrote:
> Why would you want to render distorted CG?  How/where is that being used in a pipeline?  In most cases you work out the lens distortion on the plate, de warp, track/roto/prep, integrate undistorted CG and elements and then rewarp.
>
> Maybe for an all CG render and I assume you want it to look "real" but in many cases I would argue these warp/dewarp tools are targeted at acquired plates.
>
> I'm not saying it's wrong, I'm just curious as to where in the pipeline is the benefit?
>
> Cheers
>
> On 2012-11-29, at 7:01 AM, Neil Scholes <neil at uvfilms.co.uk> wrote:
>
>> Yes absolutely
>>
>> I manged to get the precompiled binaries working in Nuke - works a treat
>>
>> I wouldn't know where to start using this info for building a Houdini lens shader!!
>>
>> Anyone out there who can? - well id buy you at least 2 pints.
>>
>> A COP node would be cool but not _as_ cool.
>>
>>
>> Neil Scholes
>>
>> www.uvfilms.co.uk
>> +44 (0) 7977 456 197
>>
>> On 29/11/12 11:48, Frederic Servant wrote:
>>> Hi,
>>>
>>> 3DE's Lens Distortion Plugin Kit (
>>> http://www.3dequalizer.com/index.php#?site=tech_docs&id=110216_01) is free
>>> to download and use.
>>>
>>> Science-D-Visions recently started to make available a lens database to
>>> feed it  http://www.3dequalizer.com/index.php#?site=tech_docs&id=120930_01,
>>> of course you can feed it your own 3DE distortion parameters.
>>>
>>> Besides Weta's Nuke plugin (
>>> https://github.com/wetadigital/lensDistortion_3de), some 3DE distortion
>>> lens shaders have been done for other renderers (mentalray:
>>> https://bitbucket.org/lamaison/lmwarpdistort/wiki/Home  and Arnold:
>>> http://s3aws.obliquefx.com/public/shaders/Obq_UVRemapLensDistortion_v204.html
>>> ).
>>>
>>> With all those examples, it should be easy enough to do a distort/undistort
>>> cop node or a lens shader for mantra.
>>> --
>>> Fred
>>>
>>>
>>> On Thu, Nov 29, 2012 at 10:29 AM, Neil Scholes <neil at uvfilms.co.uk> wrote:
>>>
>>>> Yeah I like
>>>>
>>>> in nuke you can use a plugin to match the lens distortion generated by
>>>> 3DEqualiser - which is great because it has an excellent series of ways to
>>>> model the lens of a whole range of different cameras - far better than
>>>> Nukes own lens distortion node
>>>>
>>>> Specifically the Anamorphic Model - it rocks and is really complex
>>>>
>>>> I don't have the tech to build into Houdini - but there must be a way  -
>>>> importing lens models from all the different 3D trackers out there, and
>>>> applying before you render.
>>>>
>>>> Obviously you may not want to do this on a project - but i'd love to.
>>>>
>>>>
>>>>
>>>>
>>>> Neil Scholes
>>>>
>>>> www.uvfilms.co.uk
>>>> +44 (0) 7977 456 197
>>>>
>>>> On 29/11/12 09:02, Javier Meroño wrote:
>>>>
>>>>> what about a solution like this but for real?
>>>>>
>>>>> http://www.itsartmag.com/**reviews/Lightwave9/**realcameralens.jpg<http://www.itsartmag.com/reviews/Lightwave9/realcameralens.jpg>
>>>>>
>>>>> with "for real", I mean that Lightwave (yup, that´s a Lightwave screen
>>>>> grab) lens only takes into account lens distortion and fakes the amount of
>>>>> light entering the lens with a "pin" lens effect but it´s not really
>>>>> changing it based on ISO or lens shutter. It wouldn´t make much sense since
>>>>> Lightwave´s renderer ain´t physically based right now.
>>>>> This being said, the amount of different camera lenses modelled into
>>>>> their camera shader is staggering. It´s useful if only for the lens
>>>>> distortion.
>>>>>
>>>>> If we could have a similar panel with real camera behaviour we would be
>>>>> able to choose our "starting point".
>>>>>
>>>>> regards,
>>>>>
>>>>> Javier Meroño
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>   From: jordibares at gmail.com
>>>>>> Date: Wed, 28 Nov 2012 17:59:43 +0000
>>>>>> To: sidefx-houdini-list at sidefx.com
>>>>>> Subject: Re: [Sidefx-houdini-list] Camera model
>>>>>>
>>>>>> Agreed, it is not that this particular approach is a silver bullet, just
>>>>>> trying to revisit every single part of the process.
>>>>>>
>>>>>> :-)
>>>>>>
>>>>>> jb
>>>>>>
>>>>>> On 28 Nov 2012, at 17:32, Pablo Giménez <pablogipi at gmail.com> wrote:
>>>>>>
>>>>>>   2012/11/28 Jordi Bares Dominguez <jordibares at gmail.com>
>>>>>>>   On 28 Nov 2012, at 11:35, Pablo Giménez <pablogipi at gmail.com> wrote:
>>>>>>>>   2012/11/28 Neil Scholes <neil at uvfilms.co.uk>
>>>>>>>>>   I would certainly love having a lens shader where you can import lens
>>>>>>>>>> distortion models from apps like 3DEqualiser etc.
>>>>>>>>>>
>>>>>>>>>> rather than having to render larger resolutions than needed and
>>>>>>>>>>
>>>>>>>>> distorting
>>>>>>>>> in nuke.
>>>>>>>>>>   Well, this is  debatable.
>>>>>>>>> If you "bake" the lens distortion in the render then you are forced to
>>>>>>>>> rerender in case for  soem reason this lens dostortion option changes
>>>>>>>>> in
>>>>>>>>> the future, or changes for some shots.
>>>>>>>>>
>>>>>>>> True, but the whole process is simplified as you don't need to deal
>>>>>>>> with
>>>>>>>> various sets of transformations on various points in the pipeline…
>>>>>>>> this may
>>>>>>>> be debatable, true, but I rather keep it simple and re-render when that
>>>>>>>> happens which is not that common in my experience.
>>>>>>>>
>>>>>>>>   And this happens sometimes.
>>>>>>>>> Whereas rendering some extra pixels is always a good thing,
>>>>>>>>>
>>>>>>>> I do not agree with that, I think that is a waste of rendering for
>>>>>>>> every
>>>>>>>> single pass of every single shot and you count the extra hours you
>>>>>>>> probably
>>>>>>>> would be horrified about it as I am.
>>>>>>>>
>>>>>>>>   Well, it depends on the scenario, for film, rendering 10% more pixels
>>>>>>> usually is not a big deal.
>>>>>>> But it is quite common to have shots that are really hard to render an
>>>>>>> due
>>>>>>> to changes in how it is going to be composited they needs to be rendered
>>>>>>> again and this cost more time/resources that rendering 10% more pixels
>>>>>>> in a
>>>>>>> bunch of shots.
>>>>>>> As always it depends on the scenario, being able to make the same thing
>>>>>>> in
>>>>>>> both render and comp is always good and welcome, so I don't have nothing
>>>>>>> against having a better camera model, just the opposite.
>>>>>>> Doing everything at the render stage is not always the best option, same
>>>>>>> thing goes about trying to "fake" as most as possible in comp.
>>>>>>> So a compromise between them depending on the situation is usually the
>>>>>>> best
>>>>>>> option.
>>>>>>>
>>>>>>>   just an
>>>>>>>>> overscan 1.1 will  allow you to add lens distortion in comp and also
>>>>>>>>> be
>>>>>>>>> sure that further comp manipulations like camera shakes will have
>>>>>>>>> enough
>>>>>>>>> pixels to work with.
>>>>>>>>>
>>>>>>>> I would rather have 3D camera shakes if possible… sometimes this may
>>>>>>>> not
>>>>>>>> be feasible for many reasons but...
>>>>>>>>
>>>>>>>> jb
>>>>>>>>
>>>>>>>>   I think it is better to render a bunch of extra pixels as a rule
>>>>>>>>> rather
>>>>>>>>> than be forced to rerender a expensive render.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> Neil Scholes
>>>>>>>>>>
>>>>>>>>>> +44(0) 7977 456 197
>>>>>>>>>> www.uvfilms.co.uk
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 28 Nov 2012, at 10:17, Jordi Bares Dominguez wrote:
>>>>>>>>>>
>>>>>>>>>>   The moment you enter into physically base rendering you will end up
>>>>>>>>>> wanting to use physically correct shaders and that ultimately will
>>>>>>>>>> take
>>>>>>>>>>
>>>>>>>>> you
>>>>>>>>> to realise that is actually not that useful unless you get it all
>>>>>>>>>> right
>>>>>>>>>> (physically correct camera and lights too) and also HDR balanced
>>>>>>>>>>
>>>>>>>>> properly
>>>>>>>>> (no grading)
>>>>>>>>>>> The cascade effect is huge and adapting to the approach is not easy
>>>>>>>>>>>
>>>>>>>>>> plus
>>>>>>>>> takes longer to render each frame but in my experience is more than
>>>>>>>>>> acceptable for the things you gain.
>>>>>>>>>>
>>>>>>>>>>> Ultimately, like apple did when they designed the iPad, one single
>>>>>>>>>>> rule
>>>>>>>>>>>
>>>>>>>>>> forced a ton of changes everywhere (no pen, just your finger), with
>>>>>>>>>> PBR
>>>>>>>>>>
>>>>>>>>> is
>>>>>>>>> the same and certain render engines are already there or thereabouts,
>>>>>>>>>> specially Maxwell, Vray and Mental Ray alongside all the other
>>>>>>>>>> flavours
>>>>>>>>>> inspired by these.
>>>>>>>>>>
>>>>>>>>>>> I really hope after this exchange of ideas SideFX see the value and
>>>>>>>>>>> put
>>>>>>>>>>>
>>>>>>>>>> together a physically correct ecosystem of tools for modern
>>>>>>>>>> rendering.
>>>>>>>>>>
>>>>>>>>>>> my 2 cents
>>>>>>>>>>> jb
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On 28 Nov 2012, at 10:04, Neil Scholes <neil at uvfilms.co.uk> wrote:
>>>>>>>>>>>
>>>>>>>>>>>   Interesting thoughts
>>>>>>>>>>>> I was thinking that rendering linear light values in high dynamic
>>>>>>>>>>>>
>>>>>>>>>>> range
>>>>>>>>> is the real benefit  we already have, because after that all real
>>>>>>>>>> camera
>>>>>>>>>> limitations such as abberation grain and iso can be faked in a more
>>>>>>>>>> painterly way in the comp which is surely quicker and easier ?
>>>>>>>>>>
>>>>>>>>>>> Also the issues of real world lenses and ISO etc well each camera,
>>>>>>>>>>> lens
>>>>>>>>> is going to vary in accuracy even if the camera manufacturers offer a
>>>>>>>>>> template - rather like f stop vs T stop.
>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Neil Scholes
>>>>>>>>>>>>
>>>>>>>>>>>> +44(0) 7977 456 197
>>>>>>>>>>>> www.uvfilms.co.uk
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 28 Nov 2012, at 08:50, Jordi Bares wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>   I would love that, including the camera transform matrix please.
>>>>>>>>>>>>> Jb
>>>>>>>>>>>>>
>>>>>>>>>>>>> Sent from my iPhone
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 28 Nov 2012, at 00:32, Colin Doncaster <
>>>>>>>>>>>>> colin.doncaster at gmail.com
>>>>>>>>>>>>>
>>>>>>>>>>>> wrote:
>>>>>>>>>>>   Sure!  I would assume it would be helpful if all of the camera
>>>>>>>>>>>>> parameters ended up in metadata stored in the output image - this
>>>>>>>>>> fits
>>>>>>>>>>
>>>>>>>>> well
>>>>>>>>> into the EXR camera info as it's meant to represent what exposure the
>>>>>>>>> data
>>>>>>>>> represents with a good reference point from where to adjust it.
>>>>>>>>>>>   This would make a nice COP and/or MPlay addition where you can
>>>>>>>>>>>>> quickly adjust the values and round robin them back to the scene
>>>>>>>>>> camera.
>>>>>>>>>>
>>>>>>>>>>>   Cheers
>>>>>>>>>>>>>> On 2012-11-27, at 6:17 PM, Jordi Bares Dominguez <
>>>>>>>>>>>>>>
>>>>>>>>>>>>> jordibares at gmail.com> wrote:
>>>>>>>>>>>   I don't imagine anyone aspiring to get noise simulation baked in
>>>>>>>>>>>>>> their render and with the ever expanding electronic cameras
>>>>>>>>> configurations
>>>>>>>>> and codecs this simply may be impossible but it may be useful to get a
>>>>>>>>>> metric for density of noise in the picture that we can feed into the
>>>>>>>>>>
>>>>>>>>> comp.
>>>>>>>>>   hope it makes sense
>>>>>>>>>>>>>>> jb
>>>>>>>>>>>>>>>
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>>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Un saludo
>>>>>>>>> Best Regards
>>>>>>>>> Pablo Giménez
>>>>>>>>> ______________________________**_________________
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>>>>>>>>
>>>>>>> --
>>>>>>> Un saludo
>>>>>>> Best Regards
>>>>>>> Pablo Giménez
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