topic Re: Light problem in Visualization

Light problem

Anonymous — Thu, 11 May 2023 11:43:16 GMT

Hello mates!
I 've been seaching this great forum - but didn't find any already existing tread about it:

While rendering I have a problem with light source.
Lets take halogen lamp and put it in an interior. I will have the light that it give and bright room - but I won't see any light source (highier intensity light near the bulk).
The same goes with any other light source in ArchiCad 9.

Could you please explain me how to show the highier intensity light near the light source?

Best wishes and please forgive me my language.

Re: Light problem

Dwight — Mon, 08 Jan 2007 21:18:09 GMT

Let me see:

the lamp is on and emits light, but light intensity is even, it does not reduce in intensity as distance from the lamp increases.

You are working in Archicad 9.
You are using the internal engine.
You are not selecting light falloff in the PhotoRendering Settings.

Or.

you are not telling the light to have "Falloff" in the lamp settings.

Or shadows are off.

Re: Light problem

Anonymous — Mon, 08 Jan 2007 21:34:06 GMT

Thank you for your attention Dwight!
Maybe the picture describes better what I meant...

There is no light source on the ceiling!

Re: Light problem

Dwight — Mon, 08 Jan 2007 21:39:29 GMT

I see the problem.

The problem is that you expect room lighting from Archicad lamps to illuminate the space as you would expect, when the lamps do not perform as you expect.

First, your intensity is generally too high AND your surfaces are too reflective and smooth.

If i was a photographer, I'd bring lots of fill light (in the form of a General light source) and reduce spotlight intensity until they act only as props.

NO SUCH THING AS WHITE!!!!!!!!!!!!!!!!!
make your lamps all yellow-ish.

This is truly a difficult space....

Re: Light problem

Anonymous — Mon, 08 Jan 2007 21:57:52 GMT

Walls and ceiling are WHITE in my bathroom.
And it looks really DARK.
So I guess the intensity is not a problem here...

All I need is to have the lamp's bulks glowing --> something like a lens flare effect in photoshop...

Maybe another picture can describe it perfectly...

Re: Light problem

Dwight — Mon, 08 Jan 2007 22:08:44 GMT

You want to show a light source. That's easy. Light sources are invisible.
Place a white disk right behind your light source. Make it have constant reflection.

Re: Light problem

Anonymous — Mon, 08 Jan 2007 22:13:48 GMT

Dwight wrote:
You want to show a light source. That's easy. Light sources are invisible.
Place a white disk right behind your light source. Make it have constant reflection.

You mean white circle ---> for example made of SLING?
Should I place it a bit highier?

Re: Light problem

Dwight — Mon, 08 Jan 2007 22:14:43 GMT

SLING?

Re: Light problem

Anonymous — Mon, 08 Jan 2007 22:26:50 GMT

Dwight wrote:
SLING?

I meant Ceiling tool...

I put such a disc 1 cm above light source and also behind it...
All I've got is on the pic...

What I'm doing wrong?

Once again thank you for your time Dwight

Re: Light problem

Dwight — Mon, 08 Jan 2007 23:28:07 GMT

You'll never get glare like the photoshop flare...

This image is done with some diffuse glow in photoshop - the candle flame is light over.

Re: Light problem

Anonymous — Tue, 09 Jan 2007 00:08:07 GMT

I think we misundertood each other Dwaight.
I finally managed to get the effect I wanted using reverse light:

On the picture you can see what I meant from the begining...
Thank you for help and BTW - is your book still avaible?
Greetings!
Dpistons

P.S.
Is there any kind of chance to make the same effect another way that I did it?

Re: Light problem

Dwight — Tue, 09 Jan 2007 00:27:45 GMT

My book is available.
Ordering instructions are in my post signature under this message.
I have already sent several to Poland.

The other way to make a surface look as if it is glowing is by using the "constant reflection shader."

Re: Light problem

Rob — Tue, 09 Jan 2007 03:16:46 GMT

just for the reference in the past this topic should not have had to be so dramatic if GS would have implemented some of the features mentioned in this topic:
http://archicad-talk.graphisoft.com/viewtopic.php?t=8012&start=0&postdays=0&postorder=asc&highlight=light+tool

which could save some of the pages with a tedious explanation of dodging the light settings in Dwight's book for better, brighter and lighter words when it comes to setting up our fabulously designed lighting schemes.
oh, how I miss lux, flux, watts, candelas spread over feet and meters...

Re: Light problem

Anonymous — Tue, 09 Jan 2007 13:25:41 GMT

Dwight wrote:
The other way to make a surface look as if it is glowing is by using the "constant reflection shader."

Dwight,
maybe my question will be dumb but can you tell me what is constant reflection shader and how to use it exectly?

Re: Light problem

Anonymous — Tue, 09 Jan 2007 15:29:18 GMT

Just from aside:

Generally:
It is important to understand that light has to work together with materials to get desirable effect. You can spend hours tweaking lamps/lights and still end up frustrated with uneven lit scene. Effects such as light fixture glow should be set in the end, when you first manage to fill the scene with light and get rid of deep black shadows (behind the wc) and burn outs (on the floor).

Particulary:
I would start with pairs of lightcone down + lightcone up with 130 deg cone angle each and falloff around 1 to fill the room with even ilumination. Than you will see that some of your materials are burn out (like floor for example) and you might want to decrease "diffuse" and "ambient" in matte materials or balance "roughness" and "specular" in reflective materials.
Finally, after looking for some light-fixture-glow-solution I found (thanx to Dwight) that "Wall light indirect" with "diffuse light" on is something you should try, but as I said before: only after you fill the scene with light and balace your materials. For light emmiting part of light fixture use "constant" or "dielectric" shader with high "transmitance".
Below examples show the result.
You might also want to check this topic as there is something about the light fixture as well.

http://archicad-talk.graphisoft.com/viewtopic.php?t=10074&postdays=0&postorder=desc&&start=30

Hope this helps,
Cheers

Re: Light problem

Anonymous — Tue, 09 Jan 2007 15:30:52 GMT

and another..

Re: Light problem

Anonymous — Tue, 09 Jan 2007 18:25:11 GMT

Thank you Tigr for another feedback and really great scans.
I see you have a solution for my worries!
Best wishes