Confused about emission lighting

Sometimes a filament in a light will interact with the rest of the Scene and sometimes it will not. Here in this instance I downloaded this light from blenderkit and it refuses to light up my scene. In the past I witnessed a filament light up a scene and even cast shadows. Here even when I delete the cap offof it it refuses to emit light. I see there are many posts here on the lighting forum I suppose it would help me to read some of it. I have been watching videos on lighting and how to use 3 point lighting. I have noticed that my scene can not be very large or my lights wont do a thing unless i put in something like 999999. They do not like large scale and nether does the Camera.

That’s right. Blender works on real world values, so you will notice that units are given in the inputs. Lights take an input in watts and emit what they should. Set it to 100 watts and that is what you will get (a real world 100 watt light should look roughly the same). If your scene does not follow real world scale (by ignoring the unit increments that the world has, 1 metre each), then a lot of things would have to be adjusted. Either make it the correct scale, or adjust the lights and camera to match.

Now, you did say that the cameras don’t work the same either. One of the issues would be the clip distances, which determine how far a camera can see. You can change the far clip in the camera settings to see more.

Jumping back to your initial question, I could only guess at the cause. You say that scale changes how things look, so that would be my first suggestion to check.

Apart from that, you would need to give more info (images are useful).
Does the filament visually light up?
If not, then it sounds like some other issue, such as the material is not set up properly, or something in the render/object/material etc. settings are causing this.

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It can be a problem with multi importance sampling if you have a small geometry based lamp filament in combination with larger lights. If it works much better in isolation, then you can assume this to be going on. There is not much you can do except render out in isolation and adding the images together in post.

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scale-metric-dot`testSize-lighting.blend (4.5 MB)

so here it is- I have this filament at the maximum for emission. If I go into cycles it makes a mess of noise and acts like it would take 3 hours to render if it was going to look right fireflies everywhere. I am trying to learn how to mimick lights. I watched the video form CG boost about lighting and he used a scale of .1 with metric so I am doing the same here. In the past a filament would light things up but here to day I can not make it work.
I am looking at this post Simulate Real Light Bulbs?
I am also looking at this video
When I treat meters like they were inches my 3d models are looked at like I used inches. If I use imperial and then .0254 as scale then it will show my model in inches with arch measurement addon.

I think when I loaded luxrender I may have accidentally installed a virus as OPTIMUM search hijacked
my browers. I see manufactures provide obj files with the proper lighting setup that worls wtih 3ds max but also there is way to put in values for lighting the txt profiles are here

When I turn off all other lights in the world this filament wont light anything up at all.

I am pretty sure that in the past a filament would light up my blend scene so I am missing something.

I found the answer here. I was wondering - ! It has to have a light probe. I am thinking if I want to make a light fixture I might be better off using one of the blender lights rather than using a filament and emission shader.

If your interested, I did some render setting comparisons in LuxCoreRender, using i7-4790k and 2x GTX 970s. These all used the mesh of the filament as the emitter, strength set to 100 lumens.

Standard Path Tracing (32s):

Light Tracing (32s):

Direct Light Sampling Cache (45s):

Bidirectional PT CPU (32s):

Both Bidirectional PT and Direct Light Sampling Cache with denoiser produced identical results. (5m)

Blend fie:!AnYenLI8umY-k6tXVbDZwyKL9UbJpg?e=W5xc6G

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Wow thanks for your reply. Its taking me a lot to soak it all in !

does LuxCoreRender work with those ies txt files ?

I’m pretty sure that it does support IES lights