[Sidefx-houdini-list] rectangular pbr area light

Luc Froehlicher lulu at alamaison.fr
Tue Dec 11 13:43:46 EST 2007


great.thanks
luc

Robert Magee a écrit :
> You can also parent the light to a null object and scale the null object 
> non-proportionally.
>
> The reason that Scale is not on lights by default is that scaling lights 
> can cause big problems for shadow generation when using depth map 
> shadows (the same for cameras). People often scale lights and cameras to 
> make them more visible in the scene and then the renderings don't work 
> correctly. The scale icon parameter therefore lets you change the icon 
> without affecting the shadowing.
>
> If you choose to scale your lights (using null object or edit parameter) 
> it should therefore only be used with raytracing and PBR style 
> renderings. The null object will do the trick and should be used only 
> when you are not using depth map shadows.
>
> We will put an RFE in to offer a rectangle shape in the area light and 
> offer two parameters for its size.
>
> Robert
>
> Luc Froehlicher wrote:
>   
>> Fred here show me the trick to do it:
>> Edit Parameter - > create a new vector parameter called Scale (l_s)
>> and in the Channels Tab -> Linked Channels type ./sx ./sy ./sz . it works
>>
>> another question about environment light :
>> I noticed that NoAttenuation and HalfDistanceAttenuation  gives 
>> different illumination.(this is without PBR)
>> Physically correct is always black.
>> is this correct ?
>>
>> Pablo Giménez a écrit :
>>   
>>     
>>> 2007/12/11, paul simpson <paul at realisestudio.com>:
>>>   
>>>     
>>>       
>>>> you welcome.  from what i remember mark telling me - you have to create a
>>>> new light asset with scaling enabled.  however, it's bit of a hoop to jump
>>>> through for such a common need.  i think that new users would find this
>>>> unnecessarily complex.  maybe this is a good reason to have scaling
>>>> allowable as default (MarkE)?
>>>>
>>>> i may be missing something obvious here.  i'd be keen to hear from sesi
>>>> about "best pratice" on this issue - specifically dealing with area
>>>> lights.
>>>> i'm hoping that we'll have a nice suite of lighting tools and shaders for
>>>> 9.1.  ie, uberlights, magic lights, and some bullet proof uber shaders
>>>> (made
>>>> out of lots of v useful mini shader assets).
>>>>
>>>> the quicker the power of mantra is opened up to the masses - the sooner
>>>> houdini will receive the attention (and sales) that it deserves...
>>>>     
>>>>       
>>>>         
>>> Complitely agree
>>>
>>> On 11/12/2007, Luc Froehlicher <lulu at alamaison.fr> wrote:
>>>   
>>>     
>>>       
>>>>> effectively if i parent the light under a null and scale the null it
>>>>> works as expected
>>>>> how do you add a scaling properties directly on the light ?
>>>>> thanks paul.
>>>>>
>>>>> Mario Marengo a écrit :
>>>>>       
>>>>>         
>>>>>           
>>>>>> On December 11, 2007 06:14 am, paul simpson wrote:
>>>>>>
>>>>>>         
>>>>>>           
>>>>>>             
>>>>>>> ....or, just scale the light in x.
>>>>>>>
>>>>>>>           
>>>>>>>             
>>>>>>>               
>>>>>> Heh... goes to show how much I use area lights... didn't even think to
>>>>>>         
>>>>>>           
>>>>>>             
>>>>> try
>>>>>       
>>>>>         
>>>>>           
>>>>>> that! :)
>>>>>>
>>>>>> Thanks Paul.
>>>>>>
>>>>>> P.S: hmmm... the H9 lights don't have scaling properties available by
>>>>>> default... I wonder why?... anyhoo... back to work
>>>>>>
>>>>>>
>>>>>>         
>>>>>>           
>>>>>>             
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>>>>>
>>>>>       
>>>>>         
>>>>>           
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>>>>     
>>>>       
>>>>         
>>>   
>>>     
>>>       
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>
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