[Bf-cycles] Normalized Emission shader

[David Black]

Hi Brecht,

Great to have your input.

In relation to lamp and emission plane calculation differences, can a 
light type be identified internally from its lamp ID / emission plane? 
If yes, would a more artist friendly solution be, instead of extra 
nodes, add a Normalize check box to the Emission node with a helpful 
tool-tip, something like...
"Light output remains constant while light source size changes"

Hope things are going well for you.

David

3d-designs-davidblack.blogspot.com 
<http://www.3d-designs-davidblack.blogspot.com>

On 12/11/2014 18:52, Brecht Van Lommel wrote:
> There's no significant performance hit, the surface area of the mesh
> is already computed and stored for all objects so it's just a matter
> of dividing by that.
>
> The main reason I didn't expose this option initially is because it
> raises a bunch of UI questions as you guys found. There's a single
> emission node for both meshes and lamps, so if they have different
> defaults depending if they're added to material or lamp nodes, that's
> a bit of an odd case not supported by the node system.
>
> Also related to this is how to show strength units for the emission
> nodes, it's Watts for lamps normalized by surface area and Watts/m^2
> for meshes without normalization. And there's the confusion around
> "shadeless materials", which really are just emission nodes with
> strength 1 but people keep asking how to do them, so perhaps there's a
> way to improve the UI here.
>
> Perhaps separate nodes for normalized and non-normalized emission
> could simplify things, and make it possible to show the right units,
> but then people might get confused about which node to use, so it's
> not ideal either.
>
> Brecht.
>
> On Wed, Nov 12, 2014 at 4:05 PM, Greg Zaal <gregzzmail at gmail.com> wrote:
>> Hey,
>>
>> I agree this could be useful. I'm guessing it'll work by checking the total
>> surface area which emits light and calculate the intensity based on that
>> maybe? Would there be any significant performance hit when (and when not)
>> using this feature?
>>
>> Personally I would prefer if this were not the default behavior, but we can
>> have that argument when/if it's implemented.
>>
>> Similarly, it might be useful to have the opposite behavior for regular
>> lamps - increasing the intensity as the size increases.
>>
>> Cheers,
>> Greg
>>
>> On 12 November 2014 16:27, Marco G <marco.gzt at gmail.com> wrote:
>>> Hi, i'm happy other people thinks it's useful. Thomas said it could
>>> implement it *eventually*, IF there is enough interest.
>>> @Marc Dion, actually it's geared more towards another use case, mostly
>>> flat mesh lights out of camera frustum to light subjects, withtout the need
>>> to touch anymore its strength and instead focus on size/position etc to get
>>> desired result...
>>>
>>> Hope to hear from other Cycles module member Greg and Matthew too. It's
>>> one of those optional little features which improve daily work a lot.
>>>
>>> MG
>>>
>>> 2014-11-09 21:03 GMT+01:00 David Black <db4tech at yahoo.co.uk>:
>>>> Hi Marco,
>>>>
>>>> This is something I feel would be very helpful as the default behaviour.
>>>>
>>>> While improving Sweet Home 3D's render engine results (user db4tech),
>>>> lights is one of the areas I looked at, allowing size (for soft shadows) and
>>>> intensity changes, previously lights had a small fixed size and intensity.
>>>> One of my goals, to make it easier for artists, was to try and make sure
>>>> lights intensity remained constant while size was adjusted. Certainly made
>>>> light manipulation a lot easier and received very positive feedback.
>>>>
>>>> Link: (render results image links are no longer working)
>>>> http://www.sweethome3d.com/support/forum/viewthread_thread,1688_offset,0
>>>>
>>>> David
>>>>
>>>> 3d-designs-davidblack.blogspot.com
>>>>
>>>> On 09/11/2014 17:41, Marco G wrote:
>>>>
>>>> Hi members,
>>>>
>>>> months ago a feature regarding the Emission node has been removed, the
>>>> problem is that it was never exposed to the UI but actually pretty useful,
>>>> so i'm writing to ask to bring it back if possible and if other members
>>>> agree.
>>>>
>>>> With this option enabled the total amount of emitted light is the same
>>>> regardless of the mesh size. (it would still be optional of course).
>>>> Biggest advantage it would be that once you're satisfied with how much
>>>> light you have in your scene you can resize the light without affecting its
>>>> power, for example to make it bigger to soften shadows or get bigger
>>>> reflections, without the need to adjust the strenght since it would stay
>>>> equal
>>>>
>>>> If reimplemented, maybe a flag "Normalize" exposed in the emission node
>>>> would do the job?
>>>> Tooltip: "If checked, the total amount of emitted light is the same
>>>> regardless of the mesh size"
>>>>
>>>> Opinions?
>>>>
>>>> Thanks,
>>>> MG
>>>>
>>>>
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