Can you block light?

Scavenger

I have a spot light in my scene that for some reason is projecting MUCH further that it should.
If I turn down the intensity, it'll be the wrong brightness than I need.

Is there some way to put like an invisible plane that can bock light in a scene?

Herald of Fire

Using the UberSurface shader included in Daz Studio will do the trick nicely. Just set the 'Fantom' tag on and it will become invisible to render, but visible in raytracing. A word of warning though, this means that it will ALSO be visible in any reflections, so keep that in mind when working it into the scene.

Scavenger

I just tried a quick experiment with that... Fantom seems to seems to do similar to "Not Visible in Render", so the plane I set between the spotlight and object didn't render, and light passed thru it, to the object, casting a shadow of the object....

That's actually the opposite of what I want. I want the plane to stop light from going past it, but to not be visible either. Basiclly a "the spotlight can not go beyond this point" thing...an invisible Gandalf saying Thou shall not pass!

JimmyC_2009

Have a look at this to see if it is what you need, I don't have it so I can't help more : http://www.daz3d.com/advanced-spotlight

Here is the PDF for the above http://docs.daz3d.com/lib/exe/fetch.php/public/read_me/index/17409/17409_advanced-spotlight.pdf

prixat

It sounds like you need the "falloff" parameter, which the standard spotlights don't have but the ones Jimmy mentioned do.

However the Linear Point lights have falloff controls.
I made some spots by putting the linear point lights in a cone and set various falloffs...

Herald of Fire

Scavenger said:

I just tried a quick experiment with that... Fantom seems to seems to do similar to "Not Visible in Render", so the plane I set between the spotlight and object didn't render, and light passed thru it, to the object, casting a shadow of the object....

That's actually the opposite of what I want. I want the plane to stop light from going past it, but to not be visible either. Basiclly a "the spotlight can not go beyond this point" thing...an invisible Gandalf saying Thou shall not pass!

In order for there to be a shadow the light needs to be set to cast one. The object needs to remain 'visible' in the viewport as well. Hiding it will also hide it from being able to cast shadows.

Here's a quick example of the UberSurface Fantom setting in action. The cylinder is set to use the Fantom setting and the light is cast at a slight downward angle.

Scott Livingston

As HOF said, using a plane with Fantom turned on should do the trick...make sure Raytrace is also enabled, and set the light to Raytraced shadows. However, I agree with prixat that using a light with falloff would be a better, more realistic way to achieve what you want.

Herald of Fire

Works fine with Shadow Map shadows as well, but raytraced will always give the best results in either case.

kaotkbliss

What about the ray length in the spotlight options? Isn't that sort-of a fall off for spotlights?

Richard Haseltine

No, Ray Length is one of the settings for the viewport avatar, it doesn't affect rendering.

kaotkbliss

Ahh, ok. Thank you for clearing that up for me :)

stitlown

Older post, but the closest I could find to "on point" for my issue.

And just to recap the discussion above (to the extent I read it given I'd solved <scavenger>'s original problems - with the "decay" parameter: Reminder 1=linear fall off, 2=inverse square (AKA real world) fall off. And, Yes, non integer works fine. I'm using 0.8 in a current scene because I need the light to reach a bunch of nearer stuff but not materially reach a bunch of far-away stuff.

My current issue.

• Spotlights have circular fields of effect - as duly tempered by the various light parameters.
• But, just like a theatre spotlight, I want to place some baffles to "box in" the light in certain directions.
• But I need the baffles to be invisible in a render ie they effect the light but they are not visible in the scene - much like the baffles on a theatrical light can control it, but are effectively invisible to the audience.

Within my knowledge, that can't be done in DAZ. But I know all you out there will know much better than me, so please give me some hints and pointers.

Just as an aside to the DAZ developers, Vue, many, many ,many years ago (so still today but I've not used Vue in a decade) had a parameter on each light where you could specifiy which objects in the scene it did, or did not, illuminate. A very crafty way to come up with some very theatrical lighting effects.

Looking forward to your suggestions. Cheers, Lx

 

 

stitlown

Interstingly, I could'nt seem make physical baffles (like in theatrical lighting eg a black plane to block the spotlight light) attached to the light work.  ?????

Richard Haseltine

Is this Iray? Light path expressions are not terribly user-friendly but they do allow you to limit a light's effect to only certain objects (see the Canvases sub-tab in the Advanced tab of Render Settings). In 3Delight the Advanced Spotlight does have barn door settings, I don't think there is an Iray light like that.

stitlown

Thanks Richard. I'm using 3-delight - its micromesh displacement capabilities way outshine most of Iray's other goodies for my current needs. I wasn't aware of the advanced spotlight with barnborrs, so will jump into that straightaway. Cheers. Lx

Sven Dullah

Richard Haseltine said:

Is this Iray? Light path expressions are not terribly user-friendly but they do allow you to limit a light's effect to only certain objects (see the Canvases sub-tab in the Advanced tab of Render Settings). In 3Delight the Advanced Spotlight does have barn door settings, I don't think there is an Iray light like that.

Umm, to my best knowledge the AoA lights have no barndoors, only normal light spread and support for gobos.

So to block out light barndoor style you need to use primitives just as descriibed earlier in this thread.

Quick example using an AoA spot and a primitive with UberSurface applied and Fantom active:

 

Richard Haseltine

Sven Dullah said:

Richard Haseltine said:

Is this Iray? Light path expressions are not terribly user-friendly but they do allow you to limit a light's effect to only certain objects (see the Canvases sub-tab in the Advanced tab of Render Settings). In 3Delight the Advanced Spotlight does have barn door settings, I don't think there is an Iray light like that.

Umm, to my best knowledge the AoA lights have no barndoors, only normal light spread and support for gobos.

So to block out light barndoor style you need to use primitives just as descriibed earlier in this thread.

Quick example using an AoA spot and a primitive with UberSurface applied and Fantom active:

 

OK, but some light had barndoors - I can remember fiddling with them, in a desultory manner.