[Sidefx-houdini-list] Camera model

Jordi Bares Dominguez jordibares at gmail.com
Wed Nov 28 10:42:45 EST 2012


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.

> 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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