Solid Shaft of light in blender

[Deleted User] · November 2006

i cant seem to make a straight up vertical comlumn of light in blender. A spot with a halo, but you cant make a straight column of light. it also doesnt help when the halo odesnt obey ray tracing.

any one have any ideas??

thanks

lennier1 · November 2006

It´s a long shot but did you try to let a directional light (not sure if Blender has those) project a ring-shaped map? It´s a quick&dirty solution but it usually works in Max.

Berticus · November 2006

That might work in blender. You can set a texture to be shot out from a lamp in blender (Most likely a spot) but the texture still gets larger.

-albert

lennier1 · November 2006

Maybe use the same trick they used before Lightwave was able to render true orthographic views. Place the spotlight extremely far away and use a quite narrow cone. In the area you´re interested in the result should be reasonably close to a cylinder. Hoping here that Blender can control the start and stop distances of a spotlight emission you´d be set with the next best thing to a real directional light.

Berticus · November 2006

Yerp, Blender has a start and stop distance ability. And I see what you are saying...

Also, Dallidas, you could model a simple spot light and use that. As in, a mesh that directs the light.
-albert

[Deleted User] · November 2006

Berticus wrote: »

Yerp, Blender has a start and stop distance ability. And I see what you are saying...

Also, Dallidas, you could model a simple spot light and use that. As in, a mesh that directs the light.
-albert

well i want to be able to see the shaft. The halos dont seem to care about mesh boundries.

Berticus · November 2006

set halo and ray shadow at the same time. That'll give you a halo that cares about its boundaries.
-albert

[Deleted User] · November 2006

Berticus wrote: »

set halo and ray shadow at the same time. That'll give you a halo that cares about its boundaries.
-albert

not quite..:cool:

Berticus · November 2006

There's an error in the system.
Rendered in 2.4

See the image below for more information...

[edit]I'm sorry for taking so long to reply. I had to dig the stupid thing out the mire in my hard drive.[/edit]

-albert

[Deleted User] · November 2006

hmm...well its not working for me...any ideas on how to fix it?

it also does the same thing in version 2.37

also the halo doesnt show up at all when rendered in yafray

Berticus · November 2006

Let me do some testing in a bit. I got it to work some-how and even managed to make an animation of it.

But I have a review to write first.
-albert

[Deleted User] · November 2006

thanks bert!

what review are you writing?

Berticus · November 2006

The review is in the news gallery. I went and saw Casino Royale. It was really well done. [I meant the movie.:shiner:[/edit]

-albert

Berticus · November 2006

Aright... I got it to work, see this post in the very short future for a link to a sample blend file.

Pics are below, I hope this helps.
-albert

[edit]See the bottom of this page for the download. It is titled "A Volumetric Light Test Blend."[/edit]

[Deleted User] · November 2006

it would seem that i didnt have halo step set to anything. but it still makes a cone shape...

Berticus · November 2006

Yeah... The only way I can see to circumvent that would be to change the angle of the beam to about 15 degree and move the origin of the light out a bit so you don't have a starting point...

Yeah, I'm tired... If you need a translation I would be glad to lend it...

-albert

Sphynx · November 2006

Is this the type of thing that you are after?

[Deleted User] · November 2006

exactly what im looking for

Sphynx · November 2006

Right, well taking the cube for scale, its the default when you hit Add > Cube from the men (i.e. 1x1x1). You need to modify this stuff for your own preference, but the scene is essentially:

Spot light set z=500 units upwards with an arc of 1' and the SpotBI set to 1 so that the entire thing is soft-edge. Halo on, with the intensity set to between 1 and 2.5 (again depending on what you want).

The roof and square hole is just for effect, but in this case I've also got a second halo spot set to about 7.5' arc and a SpotBI set to .25 hidden just within the conduit so that it's origin is hidden. This one gives the internal shaft of light. You don't really need it, it was just for effect.

A third halo spot light is off camera to the bottom, facing upwards. This is not required for the shaft, it's just to give a general glow. It was about 45' arc, large SpotBI value and a reasonably low energy just so that it would wash a little of the scene - remembering that halos are additive.

This image was rendered with AO turned on just to intensify the effect a little. Both the shaft spots had a little yellow added to the colour, but you could set it to whatever is actually required for your scene.

The trick here is putting the spotlight way, way back. You can't get a solid shaft because lights simply don't work like that - in real-life or in CGI. Whenever you get a solid shaft on TV or Film, chances are that its quite a complex lighting rig with a lot of lamps, all at particular angles to form the walls of the shaft. I've done this quite a bit - while I didn't go for a pure vertical shaft, The Crate image had something like 60 lamps in it to give the halo misting effect. Just remember that more halo lamps you add, the lower you need to make the intensity of each - the additive effect will just make the whole scene go a solid colour if you dont reduce the individual effects.

What you can do however, it lower the arc angle to such a degree that it becomes vertical to the human eye. This is 1', but you could go lower by pushing the lamp further back and increasing the effective distance of the lamp (this one naturally has to go over 500 units to hit the cube).

Greetings!

Solid Shaft of light in blender

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Solid Shaft of light in blender

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