View Full Version : light-meter (xpresso setup)

 georgedrakakis11 November 2006, 09:13 PMbased on this original thread http://forums.cgsociety.org/showpost.php?p=468124&postcount=1 i did this light-meter for everyone who might find it usefull. ps: i was gonna add some automated (single click) features like auto arrange the lightmeter object right under the light (vertical positioned), but i don't have time and i don't know if my xpresso skills can go that far.
sketchbook
11 November 2006, 07:30 AM
not really following what this does? can you explain the concept?

thanks!

Srek
11 November 2006, 08:36 AM
The setup allows you to determine the light intensity of a given light at the position of the light meter object, much like a real luxmeter photographers use.
Cheers
Björn

georgedrakakis
11 November 2006, 02:04 PM
The setup allows you to determine the light intensity of a given light at the position of the light meter object, much like a real luxmeter photographers use.
Cheers
Björn

tnx for the info Srek

georgedrakakis
11 November 2006, 05:28 PM
much like a real luxmeter photographers use

hey Srek,
i was just wondering, is it possible for the light-meter to determine the light intensity of more than one light in the same time?
that feature would make it act like a real luxmeterm and could be a big help to determine correct gi ''exposure'' settings.
cheers,
george

sandidolsak
11 November 2006, 07:21 PM
is that the sum of all (selected) light intensities?

georgedrakakis
11 November 2006, 07:29 PM
angelus[']is that the sum of all (selected) light intensities?

it is, but it's not a linear outcome, it's some how logarithmic.
(it's a greek term, don't know if it's the right one).
i.e. 20% of light 1 + 30% of light 2 intensity is not equal to 50% total intensity.

another issue is how to select multiple lights.

sandidolsak
11 November 2006, 07:38 PM
well i certanly dunno the math behind lights but here is an example of SUM, maybe u can put in the correct calculations :)

check the coffee node

edit: the damn thing wont update on its own, have to press execute everytime u move the meter null, dunno why atm...

georgedrakakis
11 November 2006, 08:32 PM
angelus[']well i certanly dunno the math behind lights but here is an example of SUM, maybe u can put in the correct calculations :)

check the coffee node

edit: the damn thing wont update on its own, have to press execute everytime u move the meter null, dunno why atm...

tnx ]angelus[,
i'll look @ it.

georgedrakakis
11 November 2006, 09:16 PM
check the coffee node

edit: the damn thing wont update on its own, have to press execute everytime u move the meter null, dunno why atm...

xpresso + coffee is a very powerfull combination.
i added a gui for the iteration list.
the update issue is still present.
but i am sure the answer is near -> so i better google search for the multiple lights intensity equation.

sandidolsak
11 November 2006, 12:14 AM
well i tried several diferent ways and it wont auto refresh, i hope this is not another xpresso - coffee limitation like the iterations arent passod from coffee node...
can someone comfirm that this also isnt possible?
or i made a mistake in coffee part, hope someone knows =)

georgedrakakis
11 November 2006, 10:43 AM
can someone comfirm that this also isnt possible?
or i made a mistake in coffee part, hope someone knows =)
i hope it's not a limitation and update is possible,
cause i was thinking the potentials of the light-meter.
it can really serve as a lux-meter getting light-intensity from critical areas of the scene and then suggest the ''correct'' (exposure) gi settings
for example to handle:
bounces as f-stops
and
stoch samples as iso.

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