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 Light intensity and reflexion 
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Joined: Wed Jul 11, 2007 5:36 pm
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I'm wondering why my fixtures look so dark. When I place the camera in order to see the floor, it's "normal" but when I move the camera all is too dark. It's just like there is no reflexion on the floor, on the walls, ... I've tried to adjust material properties like: Diffuse, Specular. I've put all of them at max but I don't see a big improvement. I've also tried to open your demo projects but it's the same feeling. What can I do to make my simulation looks the reality?

Best regards,
nsunier

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Nathanaël Sunier
Lighting Designer / grandMA3-2-1 Programmer
https://nathanael.sunier.net


Wed May 07, 2008 11:36 pm
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Joined: Thu May 05, 2005 11:02 pm
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Location: Kyiv, Ukraine
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This is not software bug.
Everything is calculated in correct manner.
Diffuse light reflecting in all directions, Specular light reflecting to the Camera only. Diffuse is also modulated by texture material. All reflections are modulated by the Normal vector of surface orientation. The brightness in each pixel of surface depend of fixture Lux data, Distance to surface and Smoke level. Additional fixture parameters like Zoom, Frost, Prism are changing the brightness too.

To help you solve this problem there is additional data needed:
1. Your videocard model (please also add this info to your profile).
2. Your software release number.
3. Your screenshot for one of our default installation where we can see the lights at maximum brightness.


Thu May 08, 2008 1:47 am
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1. GeForce 8800GTS
2. 301
3. see above

I've also posted some screenshot of my installation with only one fixture @ full. I've tried two different fixtures:

Juliat 310 HPC (created in LC by myself)
2170 Lux @ 5m
63°

SpotLight Combi 05PC (provided with LC)
27893 Lux @ 5m
77°

They are both placed at 6m height.

I'm very surprised by the numbers and by the result. Your SpotLight Combi 05PC looks like a 1000W PC. However the manufacter writes:

SpotLight Combi 05PC (provided with LC)
240 Lux @ 5m
56°

Why the data are fully too big? And why my 1000W spot looks like a 25W bulb? Why in both installations almost no light is reflected by the walls, ...?

Best regards,
nsunier

one of your default installation (blinders turned ON)
Attachment:
14-19_04[1].jpg

my installation (ambient @ full and one Juliat 310 HPC turned ON)
Attachment:
14-07_50[1].jpg

my installation (ambient @ zero and one Juliat 310 HPC turned ON)
Attachment:
5.jpg

my installation (ambient @ zero and one SpotLight Combi 05PC turned ON)
Attachment:
14-14_08[1].jpg

Admin: all pictures has been converted from links to the message attach.
Please do not use picture links to the other web sites.


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Nathanaël Sunier
Lighting Designer / grandMA3-2-1 Programmer
https://nathanael.sunier.net


Thu May 08, 2008 2:54 pm
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Hello nsunier,

Firs of all I would like to tell you that Spotlight COMBI 05PC is not 25W it is 650W and it has a very good optic so everything is correct. But I have changed the maximum angle from 77 to 56.

You will see it in new release of our sowftware.


Thu May 08, 2008 3:15 pm
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Hello nsunier
Quote:
Why in both installations almost no light is reflected by the walls, ...?
this is not right, the light is reflected from the walls:
Attachment:
16-08_36.png


Quote:
Juliat 310 HPC (created in LC by myself)
2170 Lux @ 5m
63°
this is not right, Lux should be done for a maximum possible output. See manufacturer photometric details.


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Thu May 08, 2008 3:18 pm
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Boomerang wrote:
Firs of all I would like to tell you that Spotlight COMBI 05PC is not 25W it is 650W and it has a very good optic so everything is correct. But I have changed the maximum angle from 77 to 56.

Yes, I've well understood that Spotlight COMBI 05PC is a 650W fixture . I was just wondering why my 1000W PC (Juliat 310 HPC, which is a good one too) shines so little.

admin wrote:
this is not right, the light is reflected from the walls:

Yes, but I'm working in a very reflective room. How can I greatly increase the reflexion?

admin wrote:
this is not right, Lux should be done for a maximum possible output. See manufacturer photometric details.

This Juliat 310 HPC fixture has the following photometric details:
8 - 63°
520 Lux @ 10m

I calculate for 5m: 520*(10/5)^2 = 2080 Lux

Can you explain me the error I made?

Best regards,
nsunier

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Nathanaël Sunier
Lighting Designer / grandMA3-2-1 Programmer
https://nathanael.sunier.net


Thu May 08, 2008 3:43 pm
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Quote:
This Juliat 310 HPC fixture has the following photometric details:
8 - 63°
520 Lux @ 10m
I calculate for 5m: 520*(10/5)^2 = 2080 Lux

Please see photometric details more carefully. 520 Lux @10m is a 5% output on the beam border. You need a 100% Lux parameter.

Quote:
Yes, but I'm working in a very reflective room. How can I greatly increase the reflexion?
- remove texture from wall material, make it white with 100% intensity on Diffuse. Disable the smoke in your room. If you need extremely reflections - set also to the maximum Specular values.


Thu May 08, 2008 4:00 pm
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