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I am working on project where I am using an infrared light. I want to simulate my real scene on blender. I am using a Cycles Render engine. I want to choose a point light. It is possible to fix a level angle visual range (45 degrees in the real scene)? The viewing range (80meter in the real scene). Any explanation will be appreciated. I need to simulate this light: enter image description here Illuminating range: Standard 45° Viewing range: 80m (outdoor)


I used the solution proposed in the create an array of lamps? to model the Infrared light mentioned above which has these properties:

  • Led quantity: 96 leds.
  • Wave length: 850nM.
  • Illuminating range: Standard 45° level angle visual range
  • Viewing range: 80m (outdoor).

The fisheye camera is installed in the ceiling in a room.

When we use the wave length node, the array of lamps does not emit a sufficient light!! enter image description here enter image description here enter image description here

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    $\begingroup$ Not sure what you mean... You want a point light that has angle limits, like a spotlight and a distance limit? $\endgroup$ – Bithur Feb 7 '15 at 17:27
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    $\begingroup$ I don't understand your question. Are you asking for parameters of the light source or for camera parameters? $\endgroup$ – maddin45 Feb 7 '15 at 17:31
  • $\begingroup$ @maddin45, my question is about light source. $\endgroup$ – BetterEnglish Feb 7 '15 at 17:34
  • $\begingroup$ @Bithur, I edited my question $\endgroup$ – BetterEnglish Feb 7 '15 at 17:34
  • $\begingroup$ related: blender.stackexchange.com/questions/24391/… $\endgroup$ – cegaton Feb 7 '15 at 23:56
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If you want to keep it in cycles, you'd better model your own lamp as anything can cast light. This way you can control the shape and with a light falloff node you can control the distance.

modeled spot

assign the correct shader : emission for the face you want to cast light, plastic or anything else for the other parts.

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  • $\begingroup$ Thanks, it seems very cool, but I have to change the color to white as in a real case. $\endgroup$ – BetterEnglish Feb 7 '15 at 18:05
  • $\begingroup$ easy as a click on color (emission node) $\endgroup$ – Bithur Feb 7 '15 at 18:07
  • $\begingroup$ You cant control the angle with this.. you would have to model the leds also.. $\endgroup$ – Jaroslav Jerryno Novotny Feb 7 '15 at 18:09
  • $\begingroup$ why not a array of modeled leds :) but the angle can be controled with the depth of the emitting faces inside the spot. $\endgroup$ – Bithur Feb 7 '15 at 18:09
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    $\begingroup$ sure, that's why a simple model fits a basic solution. But that's what makes cycles so powerful, you can make things as complex as you need. $\endgroup$ – Bithur Feb 7 '15 at 18:16
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Add a Spot Lamp to the scene, switch to Blender Render engine and set the Spotlights size(angle) and distance(falloff).

enter image description here

Position it in the scene like you want, the visual spotlights guides will help, you should see the spotlight cone and range.

Switch to Cycles if you want, but the falloff will not work there, you will have to adjust the light's strength. If you like you can use volumetrics to visualize the lights cone in render:

enter image description here

It will look like this:

enter image description here

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    $\begingroup$ there is a node on cycles for light falloff. $\endgroup$ – cegaton Feb 7 '15 at 17:52
  • $\begingroup$ Sure there is, but its not that important (strength will do) nor physically correct. $\endgroup$ – Jaroslav Jerryno Novotny Feb 7 '15 at 18:10
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Disclaimer: This answer might be better suited as a comment, but since you can not post images in comments I created an answer instead.

Sounds to me like you want to use a spot light. Spots work similar to point lights but also have an opening angle. Unfortunatly Cycles only supports round spots, not rectangular ones.

About the viewing range: In real life light will not stop abruptly, so this parameter does not really make sense in a physically based renderer like Cycles. You can however mix the emission shader of the spot with a holdout shader depending on the ray length to only make it illuminate objects in a certain range.

enter image description here

The result looks something like this:

enter image description here

At a certain range from the lamp the lightsource is treated as black. This creates the hard round 'light borders' to the left. The soft 'light border' to the right is where the opening angle of the spot ends.

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  • $\begingroup$ Thanks, but I remark that the shadow is not very clear and in the real case, the Infrared light is a monochromatic, so we get grayscale image not RGB. So, I think I have to choose precisely the diffuse of the spot. $\endgroup$ – BetterEnglish Feb 7 '15 at 18:04
  • $\begingroup$ @startingBlender I only wanted to demonstrate a method to make the light stop at a certain distance here. $\endgroup$ – maddin45 Feb 7 '15 at 18:41
  • $\begingroup$ really interesting but i'm trying to make a falloff with raylength. Something like an inverted exponential. As you can guess, my maths are not good. $\endgroup$ – Bithur Feb 7 '15 at 19:02

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