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I'm having difficulties with a Blend file:

  • Point Lights and Area lights are almost invisible
  • Sun, Spot and Hemi lights are functioning normally

By 'almost invisible' I mean that I have to crack up the intensity to 100.000 to see a dim shine. Preview pane at this level is completely blown out, as well as the entire scene if I switch to Sun, Spot or Hemi.

Does anyone have any idea what I'm doing wrong here?

A simplified file can be found at

Thanks for any pointers you might be able to give.

Warner

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    $\begingroup$ Please reupload .blend here blend-exchange.giantcowfilms.com and update your question with link. This is .blend doesn't be deleted later. $\endgroup$
    – Shubol3D
    Commented Nov 27, 2016 at 10:12

3 Answers 3

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Have you played with the "Light Falloff" node?
Just add the node into your light material and try the different falloff types.
falloff compare

But you can go further if you play with math nodes. First you need to understand how to build them:
math fallof
Constant falloff : same strength everywere, no matter if you're close or far from the emitter.
Linear falloff : strength decreasing with the distance (strength = 1/distance).
Quadratic falloff : same as linear but decreases faster (strength = 1/distance²).

Now we can play with math nodes to get tweaks and lower strength values.
tweak
I'm using your file but I had to fix your plane (removed doubles and useless perpendicular face)

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Thanks for the help with this.

I fixed the problem now. The scene -> Scale was set to 0.01 (instead of the standard 1.00) to ensure proper exporting. Even though the metric sizes were correct, it seems that Blender scales the light falloff not with the Scale rather than the Metric size.

So the solution was to re-set the scale (making the object seem huuuuge) and re-sizing the object (shrinking it by a factor 100).

Another lesson learned!

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I think everything is all right in your blend. Imagine point light as bulb. And your plane is more than 30m long. Too long to be lit by one bulb. You can use "colors" > "Light Falloff" node connected to "Strength" input in Emission node to tweak light distance. Also your world is dark, and planes are dark too - so they reflect dark, barely visible light. If you set planes material to pure black, they will reflect no light.

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  • $\begingroup$ Thanks Shubol for taking a look at this. I think, though, the lights are too weak.. Also if I make the surface white and bring the light closer to the surface it remains weak. The file I shared is a simplified version (just the floor) of a building. A room that is, say, 5x5x2.5m is completely dark, even if I put a light at 10000. How should I interpret this number, by the way? Is it equal to 'watt', or 'lumens', or neither? $\endgroup$
    – Warner
    Commented Nov 27, 2016 at 11:09

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