0
$\begingroup$

Why is the Spot light no longer working? The problem occurs when I increased the scale of the model then applied the scale. I adjusting the lamp size to 2 meters then set the strength to 5000. On my second attempt I set the Lamp size to 50cm but it made no difference. The render remains dark. If I change the lamp type to Hemi or Sun then it works fine (figure 4).

Weird thing is if I disconnect the world output node as seen in figure 3. but with the use nodes still enabled then I get this result. There is still some light on the hair but the face is completely black.

spot light settings spot light has not effect world setting: use nodes enabled Hemi lamp still works

$\endgroup$
  • 1
    $\begingroup$ I cant tell, I would upload your blend file so we can take a look $\endgroup$ – icYou520 May 2 '18 at 22:53
1
$\begingroup$

If the sun is working (the hemi light isn't supported in Cycles – it basically just acts like a sun) the problem is most likely due to light falloff of your light sources. your scene is too large for the size and strength of your lamp.

You can confirm that by adding a light falloff node to the emission of your light as shown below.

  • quadradic is the default (and real world) falloff

  • linear is a linear falloff (double the distance, half the strength of the light)

  • constant is no falloff, this is i.e. used per default by the sun lamp

enter image description here

Adjust the falloff and strength to fit your needs.

$\endgroup$
  • $\begingroup$ This works except that I had to plug constant into strength. Thanks bud $\endgroup$ – CaptainCharisma May 4 '18 at 8:04
  • $\begingroup$ That's what I meant by adjusting the falloff. Consider accepting the answer if it helped, so others with a similar problem can find it. $\endgroup$ – bstnhnsl May 4 '18 at 8:44
1
$\begingroup$

Increase the light strength to way higher than 100000.000, that's the easy solution.

I had the same problem with area lights. then I increased the strength to one million first, then reduced to my required value.

$\endgroup$
  • $\begingroup$ That is a method I usually use! If something doesn't seem to be working, change the value to something extreme. If it actually isn't changing, then there will be no difference - otherwise, you will notice the difference :) $\endgroup$ – X-27 the fluffy unicorn May 3 '18 at 13:07
  • $\begingroup$ There is something to be said about the scale of things. Cycles is designed to work with real world scales. If objects are too big, and the light sources are too far the values for the lights will need to be larger as well. $\endgroup$ – cegaton May 3 '18 at 20:23
0
$\begingroup$

Have you tried resetting the scale of the model? Maybe it's affecting the camera somehow if the problem is just in render view or maybe the world scale got messed up.

My scales were messed up once and that caused my scene to go dark because the camera was set to an f-stop that was too high. Right now your model shows .490 for x y and z.

Press CTRL-A then select scale.

$\endgroup$
  • $\begingroup$ Yes I applied the scale of all the objects but it didn't help. Still dark. $\endgroup$ – CaptainCharisma May 3 '18 at 0:51
  • $\begingroup$ It turns out only the Sun and Hemi lamps are working correctly. The rest show nothing. The weird thing is if I make a mesh light it works. $\endgroup$ – CaptainCharisma May 3 '18 at 1:11
  • $\begingroup$ 0.490 is the scale of the lamp $\endgroup$ – CaptainCharisma May 3 '18 at 1:42
  • $\begingroup$ My mistake! I'm a noob lol $\endgroup$ – genjichu May 3 '18 at 4:18
0
$\begingroup$

Smaller spotlight sizes means more coverage. See the figure below the spot lamp size is set to 20cm. The following image shows the spot lamp size at 2 meters. A little weird to be honest. However this is not the case with the female model where the lamp size and strength made no difference whatsoever. It must be a glitch. (see figure 3)

Figure 1.  Spot Lamp Size set to 20cm Figure 2.  Spot Lamp Size set to 2m Figure 3.  Spot Lamp Size set to 50cm

$\endgroup$
  • 1
    $\begingroup$ Is the other way around: smaller sizes mean that the light comes from a smaller emitter. The larger the emitter the more "coverage" the light will have. The catch is that larger sources require to be brighter, so bring up the value for strength $\endgroup$ – cegaton May 4 '18 at 0:58
0
$\begingroup$

Presto!!! Got it working. The first thing I had to go back to an earlier version of this model because I saved things incrementally just in case something goes awry, anyway... I selected everything in the scene and scaled it much larger. The goal is to have the model as close to real size as possible. To make the spot light to work correctly I added a light falloff node then plugged the constant into the emission strength. (as suggested above)

I am now aware of the inverse square law though nevertheless this is a bizarre glitch. What baffles me is the position of the lamp and it's intensity made no difference until I plugged in the light falloff node because without the node the only way to get a good result was to lower the lamp size to a tiny amount like 10-micrometers.

Presto. Its working Render without hair

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.