[Sidefx-houdini-list] rectangular pbr area light

Robert Magee rmagee at sidefx.com
Tue Dec 11 15:43:50 EST 2007


My understanding is that if you scale them at all you will have 
problems. That is why we took scale away. Of course if you put them in a 
scaled  subnet, parent them to a null that is scaled or try some other 
trick the problem will still persist. Best to keep scales away from 
cameras and lights.

Robert

Pablo Giménez wrote:
> 2007/12/11, Robert Magee <rmagee at sidefx.com>:
>   
>> 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.
>>     
>
>
> Yes I remember getting crazy renders due to a camera scaling.
> So here is the question is there any way to scale cameras and lights without
> having problems with micropoligon rendering?
> I know is not usual to scale these kind of things but only in case ....
>
> 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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>>>       
>> --
>> Robert Magee
>> Product Marketing Manager
>> Side Effects Software Inc.
>> www.sidefx.com
>> 416 504-9876 x327
>>
>>
>> _______________________________________________
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>>
>>     
>
>
>
>   


-- 
Robert Magee
Product Marketing Manager
Side Effects Software Inc.
www.sidefx.com
416 504-9876 x327





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