Light beam doesn't show

[Josip_ZG]

I've been trying to make volumetric lighting with a combination of scattering medium and spotlight.
Any combination I've tried - changing density, transparency distance, albedo, transmission, or angle, fallof and power of spotlight - it doesn't help.
All I get is light showing on the car. I tried placing light source inside the cube of scattering medium or just slightly outside of it. Video examples on YT show
it should be achieved quite easily. Am I making a basic mistake somewhere?

My laptop is very slow with this. Furthest I let it sample in realtime window is to about 40 samples. It should've already been visible by then, but it wasn't.
Spotlight was at 1200, 5500 at 25000 and 150 000 Lumen. I tried everything I could think of with values of both materials.

(light source is diagonally left and up from the car)

(doesn't show with IES light, or area lights either).

[Eric Summers]

I'm guessing you're looking for something like what I've attached, right?

What is the Beam Angle of your spotlight? Could it be that your beam is wider than your scattering medium? You could also try switching to Watts and see if the beam shows up (high Watt values make a bright light fast). One last thing - does your HDRI have any bright lights that could be washing out the spotlight?

[INNEO_MWo]

If you take a look into the spotlight.bip from the scene folder, you'll get the lighting settings you need.
I guess it is something missing in your scene like global illumination and a ground plane?!?


Hope that helps
Cheers
Marco

[Josip_ZG]

@Eric: I've tried narrow and wide light angles, it's not about that. My HDRI provides no lighting at all. I wanted everything to be done with just this one light. Maybe switching to Watts helps, thanks for your input.

@MWo: I totally forgot about that scene. I always have GI on, but the ground plane might not have been active in the scene.

[Esben Oxholm]

Hi Jozip.
Is the bottom of the cube you've used for the scattering medium material by any change interfering with your groundplane?

If yes, try and move the cube bottom below the groundplane.

Cheers,

[Josip_ZG]

Just figured out what is the problem. I tried all of yours suggestions, checked the spotlights.bip scene. Then I made a completely new scene without the car. Everything worked with all the default settings, I just applied materials and placed a sphere inside the cube. Tried basic and interior mode, it worked. Then I imported the car and the beam went missing again
Then I changed from interior mode to product mode and it showed. Why, I don't know because without the car it's visible even below 10 samples.

Below is product mode with only 2 samples and then interior mode with 15 samples in real-time.

P.S.
In the spotlights.bip it shows in both product mode and interior mode. I like to use interior mode all the time, so why would this happen? It has to be something about my laptop, probably not powerful enough. Because I'm not a newbie, I know what I can try tweaking to check most of the possibilities... I just don't bother writing down these basic things like GI, numbers of bounces, environment lighting...

[Will Gibbons]

I tried this yesterday (just coincidentally) and ran into the same thing on a 64-thread CPU, so it's not your hardware

[Josip_ZG]

That's good news... in some way...
Can it be known for sure if it's a serial problem with the whole version? Does someone else of you Shooters get results on 8.2?

I just did this today again in a whole other scene and model. It did happen again.