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Keet
Advanced Member

Netherlands
Joined: Apr 8, 2022
Post Count: 989
Status: Offline


Lighting a street light

Some time ago I created street lights and I wanted to change them into actual lights. In itself not that difficult but to make it perfect I did run into some problems.

The images show the light spread from the lights. The pink surface is the light source. The poles are 10m high and stand 50m apart, a normal configuration for highway lights

The power is set to 100% to get a nice spread but it doesn't seem enough. So how do I get a wider spread? The lighted areas between two lights should intersect a little without having to place the poles closer to each other. Another problem is that the top of the pole and the head are immensely over exposed because of the 100% power setting.

Next I tried an Invisible inward light half sphere instead of a surface light source. With a little tweaking that gives the perfect light spread. But it's no longer visible where the light comes from, i.e. the light head doesn't show as the source of the light. Of course this also means that the model width becomes as wide as the half sphere but I don't see that as a problem. It makes aligning a row of lights easy!

Unfortunately we can't have two separate light sources in the same (distributable) model otherwise a combination of the light surface and the half sphere could create exactly the light I want. Well, we can, but only with a single power setting. Mmmmm, that might just work.

I added a Invisible inward light half sphere to the street light. I made it an oval and elevated it some. Than I angled the half sphere a little to point the light towards the street. The top of the half sphere touches the bottom of the light surface of the street light. I gave the head surface light source the same name as the light source of the half sphere: 'light'. You can use different names and set them both in the Furniture Library editor but you still get only a single power setting. After export and import into a library this is the result with the power at 5%:

Now the light spread is perfect AND the surface of the street light head is also lighted. Just enough to show where the light is coming from. The pole has a little shininess and that shows in the light reflection. I would have liked to set the power for each light source individually but in this case this solution works.

There is a trick to adjust the light output of the sources a little by changing the size of the surface areas. It will take a lot of experimenting to get it right for each situation. The half sphere can be changed by setting some faces to a different material name that is still invisible but no longer part of the light source. This lowers the light output with the same power setting. The same can be done for the light surface of the head. I might try that for the head, lowering the light output a little by decreasing the light surface area. It just has to emit light and doesn't need to shine a beam of light.
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Dodecagon.nl
700+ 3D models, manuals, and projects

[Jul 27, 2024, 1:38:29 PM]

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Puybaret
Expert

France
Joined: Nov 7, 2005
Post Count: 9366
Status: Offline


Re: Lighting a street light

Nice trick. And do you have an image showing how it renders when you have more than a street light? It could help to show the difference with the second image of your post.
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Emmanuel Puybaret, Sweet Home 3D developer

[Jul 29, 2024, 9:09:02 AM]

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Keet
Advanced Member

Netherlands
Joined: Apr 8, 2022
Post Count: 989
Status: Offline


Re: Lighting a street light

Renderer: SunFlow, 400x217px, power set to 5%. The inward half sphere is W5000 D1000 H800 and angled 10° towards the street. It's elevated 137cm so the top almost touches the center of the head light. The complete model size is 48.7kB.

I have "enhanced the trick". I thought the light reflection on the top of the pole was a little too much. I now use two materials, one for the half sphere and one for the head. With a single material the head light of course went invisible like the half sphere. By using two materials I can use non-transparency for the light head.
I'm also experimenting with a head that has just a litte transparency and a light source behind it. By tweaking the transparency of the material in front of the head light source I have a little control over how the power setting is 'spread' between the two light sources. I'm happy with the current result. A nice spread of light and a visibly lighted head of the lamp.

For those who want to try this: The current Furniture Library editor has a bug that adds a comma between multiple lightsources that you list in the lightSourceMaterialName property. Until the next release you have to manually edit the library properties file to remove the commas('s) between multiple light source material names. This will be solved in the next release.
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Dodecagon.nl
700+ 3D models, manuals, and projects

[Jul 29, 2024, 11:29:32 AM]

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Sep 10, 2024, 8:34:20 AM

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