My blender-lightflow tests


(malefico) #1

OK, after bothering a dozen community members begging for help, here are the first renders of my old ashtray using Light Flow.

Thanx MrMunkily for the wonderful tut and Esshlo & Montz for your excellent script.

Check them out:

http://malefico.netfirms.com (yup, pick a language)

Yay under linux ! :slight_smile:

cheers.

malefico.


(mrmunkily) #2

nice caustix

:slight_smile:


(S68) #3

Oohhh

awesome,

I must try lightflow too, I downloaded it but sticked to the tuts… no more… yet :slight_smile:

Stefano


(Condorcet) #4

Nice. Lightflow does such a great job with glass, and antialiases great. Cig looks read, too, except you need a trail of smoke. How much time did the render take?

I don’t see any caustics, however, just light transmission. Isn’t that a different thing? Most old raytracers (except annoying ones like BMRT) will automatically calculate light transmission through a transparent substance and color the light appropriately. But castics is the light actually cast from the specular surface of an object back into the environment. Hold a light up to a glass on a table and you should see that the light passes through the glass, but that there is also a pattern cast around the glass that isn’t simply from transmission, but from reflection off the glass’ specular surface. Or, another example, shine a flashlight on a mirror and light is reflected off the mirror and back at you–that is a caustic effect, right? Light going through a substance is not. Correct me if I’m wrong.

Can Lightflow calculate this light reflected off a specular suface?

Condorcet


(S68) #5

Wait,

technically a caustic is a singularity point in Geometrical Optics field calculation (Look at my bio, this is a professional deformation :slight_smile: )

You have a caustic when several light rays concentrates in a single point/line.

Hence, for lenses, and for curved high refraction index bodies, like malefico’s ashtray, you have a caustic when transmitted/reflected rays get concentrated in a single point/line

This is the case on the lower ashtray part, where you have very highly illuminated spots.

Stefano


(eeshlo) #6

Nice work, Malefico!

It took me some time to get things setup at my stormpages site, but now the Lightflow script is available again here:
http://www.stormpages.com/eeshlo/VariousPython.html


(Condorcet) #7

technically a caustic is a singularity point in Geometrical Optics field calculation (Look at my bio, this is a professional deformation :slight_smile: )

You have a caustic when several light rays concentrates in a single point/line.

Hence, for lenses, and for curved high refraction index bodies, like malefico’s ashtray, you have a caustic when transmitted/reflected rays get concentrated in a single point/line

This is the case on the lower ashtray part, where you have very highly illuminated spots.

Stefano

I get it (not!). But I can get the same concentration of light effect in Bryce, and they (whoever they are) insist that Bryce will not calculate caustic effects, only light transmission. What about physical light reflection, like light off of water or a mirror, that will actually illuminate an object? Will Lightflow do that? I’ve tried to do it in Virtualight, but it never seems to work.

Matt


(mrmunkily) #8

I can assure you that in this case a ‘transmission’ kae caustic would look about the same as a real one, but these are definitely real. When you put a curved glass tube into bryce and shine a light into one end, the shadow dosen’t come out the other end like it would in a real tube, it comes out directly straight-lined out the other side. In lightflow it is really calculated. this is the difference


(Condorcet) #9

10-4. I get it. Thanks.

But what about my other question: can you get light to reflect off a specular surface and concentrate on other surfaces like in reality? I’ve tried this in VL, say with simple objects (a shiny ball with caustics turned on, a light, and a diffuse floor) and no light ever reflects off the ball and onto the floor.

Matt


(mrmunkily) #10

Yes: Lightflow can do both reflective and refractive caustics. I’ll do s demo of this soon. until then you can see an interestic effect of reflected caustics simulated in lightflow here

http://www.hypercomplex.org/lightflow.htm


(malefico) #11

On 2002-03-19 05:07, Condorcet wrote:
Nice. Lightflow does such a great job with glass, and antialiases great. Cig looks read, too, except you need a trail of smoke. How much time did the render take?

I don’t see any caustics, however, just light transmission. […]
Condorcet

Thanx Condorcet, but reading your post makes me think… did you see the right picture ? I mean, there is no cigarette on the Lightflow pictures, that one is PURE Blender. Sorry if I got the wrong impression from your post.

Cheers.

malefico.


(Condorcet) #12

Hmm. I never saw a picture of an ashtray without a cigarette. I’ll look again.


(Condorcet) #13

Well, what do you know, I was looking at the wrong one. Now I do indeed see the caustics. Cool. Neat.

C


(malefico) #14

OK, there you have caustics ! :slight_smile:

Cheers.

malefico.


(paradox) #15

Ha Ha, I too was looking at the wrong picture. Didn’t see that much of a difference until you pointed out the caustics pic had no cig. Now I found the right ones. Very cool looking.
Embarassing.

Paradox


(malefico) #16

It was my fault, I was too lazy too update the gallery page… now it’s updated :slight_smile:

seeya.

malefico.