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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Thu May 11, 2017 10:12 am 
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Richard Burton wrote:
It would be interesting if a ray tracing program was able to give some kind of value to the contrast displayed in the stone at any particular tilt/lightsource moment.


On it! :D

Image

There are two potential metrics here: Contrast, which can be measured by looking at where each facet gets its light from (the color map), and Scintillation, which is the change in where the light comes from as the stone is tilted. I'm hoping to incorporate both into a future optimizer, but even just turning on contrast ring view and spinning the stone around in the raytracer gives you a pretty good idea.


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Thu May 11, 2017 1:02 pm 
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Excellent job! :)


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Thu May 11, 2017 4:16 pm 
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Hi Marco

I cropped these pics from screengrabs of your video - how can you not like Rosella? :smt017

(Hope the attachments come through - I have never tried it before!)

Martine


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Thu May 11, 2017 4:27 pm 
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Second try - had to reduce Rosella's files:

Attachment:
Amethyst in Rosella by Marco Voltolini 7 https vimeo.com[SLASH]25960356 sm.jpg
Amethyst in Rosella by Marco Voltolini 7 https vimeo.com[SLASH]25960356 sm.jpg [ 18.54 KiB | Viewed 753 times ]
Attachment:
Amethyst in Rosella by Marco Voltolini 6 https vimeo.com[SLASH]25960356 sm.jpg
Amethyst in Rosella by Marco Voltolini 6 https vimeo.com[SLASH]25960356 sm.jpg [ 18.46 KiB | Viewed 753 times ]


Martine


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Fri May 12, 2017 3:12 am 
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Mailaletto and Rej.
My brains hurts after all that reading! 'Plug and play' for me please!
Good job =D>


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Fri May 12, 2017 11:06 am 
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AlBalmer wrote:
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I can't seem to see the instructions for Longs Wittlesbach replica.


On a PC, they are easily readable from the GemCad main screen, but only barely readable if printed. Apparently this is because GemCad is squeezing 105 separate lines of instructions on a single page. I'm afraid iPads aren't good for everything.

Just looking at it, there appears to be enough symmetry that one of our clever designers could come up with a good approximation with far fewer angle changes.



Hi Al,

I'm sorry, I thought I had answered you.

Unfortunately for me, all I have right now are apple products :(

As such, the Wittlesbach instructions are impossible to read on pdf, and I can't seem to download the GemCad version at all.

Oh, well. I can't really complain, because the ipad was a gift. More like a Trojan horse, actually.


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Sat May 13, 2017 3:02 am 
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Rej wrote:
Richard Burton wrote:
It would be interesting if a ray tracing program was able to give some kind of value to the contrast displayed in the stone at any particular tilt/lightsource moment.


On it! :D

Image

There are two potential metrics here: Contrast, which can be measured by looking at where each facet gets its light from (the color map), and Scintillation, which is the change in where the light comes from as the stone is tilted. I'm hoping to incorporate both into a future optimizer, but even just turning on contrast ring view and spinning the stone around in the raytracer gives you a pretty good idea.

Rej:

Have I told you recently that I love you? :D


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Sun May 28, 2017 11:29 am 
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I am trying to design a pear shape to use with a piece of garnet rough. Where can I find instructional help on how to do a pear design.
Thanks,
Alex


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Sun May 28, 2017 12:11 pm 
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Martine wrote:
Second try - had to reduce Rosella's files:

Attachment:
Amethyst in Rosella by Marco Voltolini 7 https vimeo.com[SLASH]25960356 sm.jpg
Attachment:
Amethyst in Rosella by Marco Voltolini 6 https vimeo.com[SLASH]25960356 sm.jpg


Martine


Wow. This is very beautiful. I don't remember seeing this design on the gem. Project, but perhaps I overlooked it. Thank you for posting this!


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Mon May 29, 2017 9:32 pm 
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Alex Edwards wrote:
I am trying to design a pear shape to use with a piece of garnet rough. Where can I find instructional help on how to do a pear design.

Hey Alex, unfortunately pears (even moreso than marquises) are difficult to design such that they look good. There'll always be some unpleasantness as you transition from the body to the tip, and minimizing this while avoiding things like windowing and bowties is pretty difficult compared to rounds or other easy shapes.

I don't know of any instructional help on designing pears, either. Kim, do you know any sources?


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Tue May 30, 2017 5:53 am 
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I agree Arya, performance issues are apparent in most pear designs at some point across the tilt, its symptomatic of the bilateral symmetry. You can work around that issue by utilising three or more degrees of symmetry on the culet tier and make the design more broad (i.e. fat). Its no guarantee of a performing pear but you have a better chance of getting the design to where you want it.

I'd also recommend avoiding sharp angle changes where possible, as they create light leakage areas that are easy to see as the stone tilts.

If you need to stick to bilateral symmetry, a 'Lazy' facet arrangement on the pavilion often delivers good results as it seems to widen the light return across the pavilion on a longitudinal tilt.

And if all else fails just cheat and cut the design in CZ after optimising it ;) lol

Below is a bit of a muck around I had with the Cullinan design the other week. The result is ok, but could do with a bit more tweaking. Have fun Alex :)

Cheers,
GR


Attachments:
Cul Rejigged Graph.jpg
Cul Rejigged Graph.jpg [ 172.81 KiB | Viewed 512 times ]
Cul Rejigged Pic.jpg
Cul Rejigged Pic.jpg [ 130.75 KiB | Viewed 512 times ]
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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Thu Jun 01, 2017 7:13 am 
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Thanks Arya and Gem Ranger, I have settled on the "Beginner Pear" design
by Michiko Huynh, it actually fits the rough really well. The pavillion is almost done, just need to polish. I will post a picture when done.

Alex


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Sat Aug 12, 2017 2:04 pm 
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I am looking for a pear design for ruby laser rod... I like old fashioned as opposed to modern cuts... about to go dig out the Long and Steele books but thought I'd throw out this request as a possibility also: the Ikeda Acorn (gemology project) with crown and pavilion angles optimized for sapphire. ? Also interested to entertain other suggestions...


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Sat Aug 12, 2017 3:50 pm 
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from norman steele, 5051 pendeloque, using their angle "translation", wonder what ruby rod would look like (design angles P: 41 C: 37)
P1 / C1..........41............41.2
P2 / C2..........42.7.........41.2
P3 / C3..........46.6.........41.2
P4 / C4..........47.0.........41.2
P5 / C5..........42.0.........41.9
P6 / C6..........43.9.........41.9
P7 / C7..........90............40.5
P8 / C8..........90............38.4
P9 / C9..........45.3.........33.1
P10 / C10......47.1.........37
P11/ C11.......90............37
P12 / C12......90............37
P13 / C13......50.2.........39.3
P14 / C14......49.1.........29.6
P15 / C15......90............15
P16 / C16......90............15
P17 / C17......46.9.........16.4
P18 / C18......43.7.........0
P19................90
P20................90
P21................39.8
P22................90


would like to do J.Graham's Utopia but this rough is I think too small for that one.


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 Post subject: Re: From the GPU - post your GemCAD design requests here!
PostPosted: Sat Aug 12, 2017 4:42 pm 
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This is how the Mehenge garnet turned out. This is the "Beginner Pear" design
by Michiko Huynh. It ended up being .75 ct.


Attachments:
File comment: .75 ct Mehenge garnet, rough from New Era Gems.
IMG_9029_edited-1.JPG
IMG_9029_edited-1.JPG [ 39.15 KiB | Viewed 222 times ]
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