How Can I Not Make the Rest of It

I just wanted to see how they made old Fresnel lenses. Now, I’ve done it. It feel compelled to make the rest of the lighthouse.


…and what will be the RBG value of the light source? re: RGB Values of Various Lights :thinking:
Have fun ! :slightly_smiling_face:

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You were right that it was not a coincidence. It was the values for halogen incandescent.

I think that I can fake chromatic aberration in Cycles, by varying the color of the light, and the Index of Refraction, but first, there is much to be done.

Index of Refraction for Borosilicate Crown
Color wavelength (nm) Index of Refraction
Red 640 1.50917
Yellow 589 1.51124
Green 509 1.51534
Blue 486 1.51690
Violet 434 1.52136



You indeed can fake chromatic aberration by adding a set of Glass BSDFs, exactly set up with the IORs and color values as you give. I believe you can stick to three BSDFs, for Red, Blue and Green with the IORs set to what you have in the list.


Thanks Nathan.

While RGB lacks some gamut/spectrum areas, such as cyan, yellow and magenta, but it might come out okay, as long as I get the lighting values done first with the standard whitish light. My monitors have no CYM pixels channels anyway.

I was experimenting with using separate layers for each light/glass combination, and switch them on/off for each colored render channel, and then stack them up in Photoshop. There should be an accumulative denosing effect in the intensity sense.

I had thought of using Grasshopper, with a plugin to modify the material values, in addition to the light values, and kick off the renders. First, I need to finish the light and lighthouse.

Nathan, please don’t read this because you have enough (too much) to deal with: [Theoretically, a function could be written for Rhino to go through its object list, look for lights and materials, and temporarily change the values, such as dividing light brightness while changing the color, as well as varying the IOR appropriately. Chromatic aberration could be automated, without resorting to forward/reverse pathtracing, as I understand it. The resultant render would take a long time.]

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FYI, there is a small team working on making Cycles into a spectral renderer:

Towards the end of the interesting and huge thread (I believe from posts 400-500 onward) you should be able to find test builds of Blender that have this spectral renderer version of Cycles in.

The entire thread is a very good read, lots of discussion about wavelengths, color etc.

I believe that at some point, with spectral rendering in that build getting better, it should be possible to introduce more caustic effects.


a fake refraction render i was messing with a while ago

the render tool i used did not provide more than 2 colors of CA so playing with different refraction values and exporting each as a different rgb helped composing the final image. since this effect is pretty commonly used currently (i believe mostly with the help of aftereffects) this naturally will have some attention to it.

you think that once that has been released you could get that into rhino? i am still not using blender due to the still pretty different work flow, would love to use such gimmicks in rhino rather.

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If spectral work ends up in Cycles then eventually it’ll flow to Raytraced and v7 RR.

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The gem people, and you know who you are, will like that.

That is a great result!

Now that I making the rest of it I am worried that it needs something to be on. I am almost to making the first order fresnel lens.

Built from Library of Congress drawings, the windows were a bit confusing, there aren’t any windows on the north-west/south-east sides.

The funny thing is that from time to time, I felt a sense of heights. :crazy_face:


now put it onto a little hill place it next to the water, paint it pink and let the light shine out volumetrically while a ship passes by in the background! all in a mooded foggy dawn light of course :slight_smile:

I’ve experimented adding planar fog, but I am not good at it.

hmm yes i use a different renderer for this, but in rhino you could experiment a bit with the dashed version of ShowZBuffer meaning -ShowZBuffer which gives you the option to invert. might add some fancy foggy mood.

@nathanletwory are there any ways to fog up the scene with cycles?

If we had a density texture (3d noise) and all volume related nodes wrapped then that’d be the best shot. I’ll put it on my fun-to-do-when-all-other-todo-is-done list :slight_smile:

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And a diner for visiting tourists… All those nice reflective surfaces.:wink:

Edit: In the following post, I made a mistake by misjudging someone’s intentions. I am sorry. I was wrong. In the same way that lighthouses were made to serve as a warning to others, for now, this post might serve as a reminder to myself and an example to others to be more cautious about miscommunication.This post may be removed in the future.

[ “And a diner for visiting tourists… All those nice reflective surfaces.”

Jeremy, Is there some reason why you are being aggressive? :pouting_cat:

I have bragged to many people in person, and on line that Rhino 3D’s forum is one of the best, if not the very best commercially owned support forums that I have been on. It’s not that your dig was so deep, but here it stands out.

Yes, I am the kind of person who likes to make things, and not have to worry too much if there will be rendering problems. Oddly, from what I am told: Rhino has comparatively (v6) more problems with multiple lights and texture load–than reflective surfaces. It has been said that progress is being made on the later. When I find an interesting or challenging building, I make like to them. I also did a study of a building here in the San Jose area. Years ago, I drew a 1960s Nike Missile installation than ran in Quake 2 and Quake 3 engines.

*[The diner, was a near copy of “OD” or Olympia diner, one of only a few remaining The O’Mahony Diner Company diners, from the 2000 or so that were built. The OD diner is a interesting landmark in Connecticut, USA. In the 1950s and 1960s, it was said that on the weekends the the car people would meet there and race for pink-slips (legal automobile title).] *


Anyway, I found a nice background on I have half of the Fresnel lens done. Viewed at angles the light flashes. Here, I turned the view the the lens just glints.

[Rendering-wise it’s interesting, because there is no surface or incandescent model to cause the flash. In the center of the light, there octagon of rectangle surface lights. The material used on the lens glass is not completely transparent. The glass weakly absorbs the light, and reflects the light coming from the one across from it. If there were gain medium, it would be a laser simulation. There is one point light in the center, which may or may not stay.]

It needs a door on the top level, the support under the platform, holes under the sphere part of the finial. In the originals, the upper part is considered a lantern. The holes let out the fumes from the lamp. In the originals, the lens turned from a clockwork powered by a chain that went down the stair column. (There are only 9 stairs in my drawing, at the top. Some of the originals had a platinum tip at the top. :money_mouth_face: )


Hi @Brenda,
I have no idea how you could possibly find my post aggressive. I find I am hurt by your response.
I thought your diner was fantastic and I thought it would be an interesting challenge to combine light from the lighthouse with your beautifully rendered internal lighting, particularly with the mix of metal and glass surfaces.

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Well, then… I am sorry.

I see that you did give me a like on it. In another thread, someone didn’t care for the rendering, I’ve been rending a lot of stuff, and saving that one for last to make it better. Because of the off-comment someone else made, it has made me a little defensive about it the project.

We only have these 26 characters, and a few marks to do our thing. It read like you were taunting me, complete with a wink emoji.

If you did not mean to be mean, how may I help fix it?
We can have the post removed. We can leave it as it is as a warning to others. I can edit it to point out my mistake.

That thing a wrote about this forum being exceptionally good, I meant it. I want to preserve it. That said…

I am sorry that I mistook your communication, and responded inappropriately. I made a mistake.