[Sidefx-houdini-list] Camera model

Neil Scholes neil at uvfilms.co.uk
Thu Nov 29 05:29:46 EST 2012


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
>
> 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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