I want to create Christmas tree lights for a scene that may become a 
Christmas card.  I'm thinking of using the MegaPov glow feature, but because 
they will be somewhat close-up, I'm not sure it's up to the task.  Ideally, 
the bulb would be visible, yet still emitting some light.

Does anyone else have any experience with this?  If not, any help on which 
direction I might want to pursue would be appreciated (emitting media inside 
an object, etc.)  Basically, I just want a fairly realistic looking 
christmas tree, but the tree and balls I've got handled.

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Jeremy M. Praay wrote:
> I want to create Christmas tree lights for a scene that may become a 
> Christmas card.  I'm thinking of using the MegaPov glow feature, but because 
> they will be somewhat close-up, I'm not sure it's up to the task.  Ideally, 
> the bulb would be visible, yet still emitting some light.
> 
> Does anyone else have any experience with this?  If not, any help on which 
> direction I might want to pursue would be appreciated (emitting media inside 
> an object, etc.)  Basically, I just want a fairly realistic looking 
> christmas tree, but the tree and balls I've got handled. 

So, do you want a halo around the objects? Or do you want somebody to 
model the bulbs for you? If it's a halo you want, I do have experience 
in that department. I've got a version of my luminous bloom code which 
takes HDR images as input, and (slowly) spits out the image with halos 
around the bright parts. You would have to give the bulbs (or the 
filaments inside them) really high ambient values, and output the first 
render to HDR format. You would need to use 3.7b or MegaPOV for the 
whole process. If you wish to pursue this route, let me know and I'll 
post the updated luminous bloom code (I should post it anyway).

Sam

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"stbenge" <THI### [at] hotmailcom> wrote in message 
news:490b59fc@news.povray.org...
>
> So, do you want a halo around the objects? Or do you want somebody to 
> model the bulbs for you?
If anyone has already done it well, sure.  I wouldn't want someone to write 
my code for me, though.  ;-)
Mostly, I just didn't want to reinvent the wheel here.  The problem is that 
some things which look good from a distance, won't look very good on closer 
inspection.

> If it's a halo you want, I do have experience in that department. I've got 
> a version of my luminous bloom code which takes HDR images as input, and 
> (slowly) spits out the image with halos around the bright parts. You would 
> have to give the bulbs (or the filaments inside them) really high ambient 
> values, and output the first render to HDR format. You would need to use 
> 3.7b or MegaPOV for the whole process. If you wish to pursue this route, 
> let me know and I'll post the updated luminous bloom code (I should post 
> it anyway).

Later tonight, I'm planning to play around with the Megapov glow features, 
and see how it looks.  At this point, I'm really not sure how they do what 
they do, and whether or not they'd be suitable.  Maybe I'll use them in 
conjunction with regular light sources, or maybe something else...

If I understand how you describe your luminous bloom code, if you have an 
object with a really high ambient value, it will "bleed" into the 
surrounding pixels.  I guess I wouldn't know for certain until I've tried 
it, but that sounds kind of like what I'm after here.

Perhaps I'll end up with some combination of effects.  Time to start 
experimenting...  If I come up with something good, I'll certainly share the 
code and concepts with anyone who requests.

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Jeremy M. Praay wrote:
> "stbenge" <THI### [at] hotmailcom> wrote in message 
> news:490b59fc@news.povray.org...
>> So, do you want a halo around the objects? Or do you want somebody to 
>> model the bulbs for you?
> If anyone has already done it well, sure.  I wouldn't want someone to write 
> my code for me, though.  ;-)

The bulbs or the halo? You have to be specific :)

I won't model the bulbs for you, but if you want to speed the process 
up, you could probably model them in Blender or Wings... Blender makes 
it easy to add thickness to a mesh, but if you aren't familiar with the 
program, you may find yourself mired deep in a steep learning curve...

> Mostly, I just didn't want to reinvent the wheel here.  The problem is that 
> some things which look good from a distance, won't look very good on closer 
> inspection.

In that case, CSG objects may be the ticket here. A blob object or two 
sor's could make a nice glass bulb shape.

>> If it's a halo you want, I do have experience in that department.
> 
> Later tonight, I'm planning to play around with the Megapov glow features, 
> and see how it looks.  At this point, I'm really not sure how they do what 
> they do, and whether or not they'd be suitable.  Maybe I'll use them in 
> conjunction with regular light sources, or maybe something else...

The glows are nice for many things, and may in fact work for this 
particular project. For instance, for an incandescent bulb you could 
create a series of glows along the "filament." This would look nice for 
closeup shots.

> If I understand how you describe your luminous bloom code, if you have an 
> object with a really high ambient value, it will "bleed" into the 
> surrounding pixels.  I guess I wouldn't know for certain until I've tried 
> it, but that sounds kind of like what I'm after here.

Yes, that's pretty much how it works. The HDR version of my code works 
very well for stuff like this. The effect has an affinity for bright 
values(eg. rgb<20,10,10>); lower, more typical values (eg. rgb<1,.5,.5>) 
do not produce a very visible glow. The HDR version is slower than the 
regular version which is already very slow. Plus, I never extended the 
program to use more than 256 color_map entries, so you are limited to 
about 227 samples max (because the samples are evenly spaced points in a 
disc). I might be able to optimize the code to squeeze a few more 
samples in there, since I probably used fractional loop counters ;)

> Perhaps I'll end up with some combination of effects.  Time to start 
> experimenting...  If I come up with something good, I'll certainly share the 
> code and concepts with anyone who requests.

Well, if you need the luminous bloom code right away I'll try to make it 
presentable very soon. Otherwise I'll be taking my time. The MegaPOV 
glow idea will probably work, though.

Sam

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"stbenge" <THI### [at] hotmailcom> wrote in message 
news:490b761e@news.povray.org...
> The bulbs or the halo? You have to be specific :)

The bulb shape I can probably handle. The halo, light source, etc, and any 
media is the challenge.
>
> Well, if you need the luminous bloom code right away I'll try to make it 
> presentable very soon. Otherwise I'll be taking my time. The MegaPOV glow 
> idea will probably work, though.
>

Thanks for the insight.  I'll probably just do some experimenting and post 
in p.b.i and go from there.  :-)

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