Light power Tweet

[davorin]

Hello (o;

For Octane I have to use emissions on object to use as lights...

Is it normal that I need to set emission power to 100000 and more?
I thought this power was related to something like wattage...

[J.C]

Hi, according to manual emission power is a wattage number.
How did you setup your light in a scene? Maybe the scale is wrong.

[davorin]

I just added a sphere with black body emission and default values....then changed power from 100 to 100000...

The sphere is around 35cm above the plane...

[J.C]

Something is wrong. Can you share the scene?

[davorin]

Well I have the same problem with high power when I use a bitmap as light source...

Here is the sample scene...

[J.C]

Increase Texture value to something close to 1. This should help.

[davorin]

That works...thanks....whatever this field is for

Wonder why it is not set to 1 by default...

[J.C]

You can scale the light mesh too to increase brightness.

The texture value is:

"This setting is used to set the efficiency of the light source. This can be set to a value or a texture. Its important to keep in mind that in the real world lights are never 100% efficient at delivering the power at the specified wattage (a 100 watt light bulb does not actually deliver 100 watts of light.) The efficiency setting can be used to enter the real world values.

[J.C]

Looks like increasing Efficiency is wrong.
Some interesting read about it:

viewtopic.php?f=30&t=42275&p=313725&hilit=lumen#p313725
viewtopic.php?f=9&t=62045&p=317233&hilit=lumen#p317233

[J.C]

Well I have the same problem with high power when I use a bitmap as light source...

Here is the sample scene...

In your scene there is one mistake. You need to "Apply Scale" to the mesh object so it's scale is 1. If you fix this you can use real world value efficiency values and wattage values too.