An interesting (to me) ASET comparison -- JA vs. DiamCalc

[drk14]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

Dave's ASET DiamCalc photo seems to have dispersion on - I like to turn it off.
The DiBox ASET has a slightly larger (black) hole to enable photography than the DC version.

Is this why some regions that were blue in the DiamCalc ASET are black in the JA ASET? I assume JA uses DiBox?

And what will be the effect of turning dispersion off vs. on in the DC ASET?

 

[drk14]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

So im going to give you the info for doing it yourself.
There is what I call mush or areas of ineffective or near infective VFs often combined with leakage.
They look like blurry mush in person and in pictures.
In the JA vids to tell if your seeing mush or blurry photo look at the facet junctions and look for changes in that are as you move from one image to the next if you see fairly clear signs of VF flash even blurry it is likely photo related. Do that for all 4 diamonds you posted and you will see it clearly.

So if I understood this correctly: If there appear to be VFs that turn on/off abruptly as the stone rotates, but they look blurry, then it is explained by an unfocused camera. On the other hand, if the blurry looking VFs do not transition abruptly from light to dark as the diamond rotates, then they are truly "ineffective" or "mushy" VFs. In the latter case (mush), would the ineffective VFs not change brightness at all (or very little), or would they undergo the kind of gradual ("dimmer" effect) transition that you were describing earlier?

Thanks!

 

[Karl_K]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

So im going to give you the info for doing it yourself.
There is what I call mush or areas of ineffective or near infective VFs often combined with leakage.
They look like blurry mush in person and in pictures.
In the JA vids to tell if your seeing mush or blurry photo look at the facet junctions and look for changes in that are as you move from one image to the next if you see fairly clear signs of VF flash even blurry it is likely photo related. Do that for all 4 diamonds you posted and you will see it clearly.

So if I understood this correctly: If there appear to be VFs that turn on/off abruptly as the stone rotates, but they look blurry, then it is explained by an unfocused camera. On the other hand, if the blurry looking VFs do not transition abruptly from light to dark as the diamond rotates, then they are truly "ineffective" or "mushy" VFs. In the latter case (mush), would the ineffective VFs not change brightness at all (or very little), or would they undergo the kind of gradual ("dimmer" effect) transition that you were describing earlier?

Thanks!

yea they might go dimmer.
Using bad information ie blurry photos there will always be some question.
But if you have a blurry area and it doesn't change much with a wide range of rotation then it is most likely the diamond has some mush. One of those diamonds has a very large area of mush just off from the center.

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

https://www.pricescope.com/forum/rockytalky/yellow-in-an-aset-t153335-30.html
PS discussion about Yellow in ASET.
you may find here Rhino example ( real photos of cushion ) and photos from AGS article with yellow ASET zones in Round cut!

http://agslab.com/spie/spie_lo_res.pdf

there are many other strange comments about VF's, ETAS,.. in current discussion

Serg,
I'm not sure what was determined in the referenced thread with regard to yellow color. There is discussion of "mixing" of red and green to make yellow (which does not seem very intuitive to me), there is mention of the contribution of dispersion, and yet other discussion about the body color of the stone being magnified by internal reflection before exiting through the pavilion as leakage.

I also see the yellow shown in the AGS article - in the "actual photo", but not in the CG. Since body color is not a factor in AGS CG ASET, I assume that accounts for why there is yellow in the actual but not the CG. HOWEVER, if you look at the ASET matrices of secondary refraction (figure 25) you do see yellows, and perhaps to a lesser degree in some tilt views. So, is the yellow being modeled by AGS somehow a function of dispersion?

Bryan,

it is hard to see details on fig.25. Link to high resolution does not work. Images on fig .25 do not look correct from my point of view. It is necessary a additional information to understand the reason on yellow on fig.25( may be just the low resolution is reason of mixed green and yellow)
in any case I do not see any connection between this picture and statement about yellow in Diamcalc images and real ASET photos.
To be honest I do not see connections between real world and many statements in this thread . most posts are just not clear for me.

Hypothesis about crispy facets, Important factors:
1) Frequency / flash duration
2) Flash size
3) space Distribution
4) Number internal reflections and quality of polishing. mirror with bad flatness can not give sharp image( to receive high quality image you need High MTF value http://en.wikipedia.org/wiki/Optical_transfer_function) . if several mirrors create image than total MTF is multiplication of MTF each mirror. MTF value is less than 1.
So facet with less internal reflections give more sharp lights source image( more crispy) .
usually small fancy cuts facets has worse polishing ( less MTF) . so there are 2 reasons why most fancy cuts are less crispy than RBC.
But some Fancy cuts may be so crispy or even more crispy than best round diamonds.

 

[Karl_K]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

Hypothesis about crispy facets, Important factors:
1) Frequency / flash duration yes very important, haven't got to it yet
2) Flash size yes very important, haven't got to it in detail yet
3) space Distribution yes very important, discussed it a little.
4) Number internal reflections and quality of polishing. mirror with bad flatness can not give sharp image( to receive high quality image you need High MTF value http://en.wikipedia.org/wiki/Optical_transfer_function) . if several mirrors create image than total MTF is multiplication of MTF each mirror. MTF value is less than 1.
So facet with less internal reflections give more sharp lights source image( more crispy) .
usually small fancy cuts facets has worse polishing ( less MTF) . so there are 2 reasons why most fancy cuts are less crispy than RBC.
But some Fancy cuts may be so crispy or even more crispy than best round diamonds.

The last is what I was discussing but in more simple words with an explanation using ETAS on how diamond work by picking up light in various areas of the environment and returning it to viewers eye.
If you don't understand that then you cant understand the rest.

All of the factors Serg mentioned are very important to scintillation I don't think anyone can dispute that.

 

[MelisendeDiamonds]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

Sarin/DiamCalc ASET:


This is an interesting question and one that could help with the overall interpretation of ASET images.

Where is the yellow color coming from in the above image (the original CG ASET that drk posted).

When you add Green Light to Red Light you get Yellow light.
When you add Blue Light to Red Light you get Purple light.

If a light ray exiting the crown draws light from 45 (+/- 2 degree) degrees, that area of the crown lit by that ray will be comprised of two colours Green and Red, the larger the size of the ASET cone the greater the component of both colors and thus the more likely we will see yellow.

The default Diamcalc ASET simulation parameters make the ASET cone much larger (Serg mentioned 3X larger previously) than the ones most people use in real life so mixing of colors at the borders is enhanced more than in most photography setups. By adjusting the ASET lighting in DC one can make it more inline with your particular photo setup.

 

[MelisendeDiamonds]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

 

[MelisendeDiamonds]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

So im going to give you the info for doing it yourself.
There is what I call mush or areas of ineffective or near infective VFs often combined with leakage.
They look like blurry mush in person and in pictures.
In the JA vids to tell if your seeing mush or blurry photo look at the facet junctions and look for changes in that are as you move from one image to the next if you see fairly clear signs of VF flash even blurry it is likely photo related. Do that for all 4 diamonds you posted and you will see it clearly.

So if I understood this correctly: If there appear to be VFs that turn on/off abruptly as the stone rotates, but they look blurry, then it is explained by an unfocused camera. On the other hand, if the blurry looking VFs do not transition abruptly from light to dark as the diamond rotates, then they are truly "ineffective" or "mushy" VFs. In the latter case (mush), would the ineffective VFs not change brightness at all (or very little), or would they undergo the kind of gradual ("dimmer" effect) transition that you were describing earlier?

Thanks!

I don't like the terms "effective" or "ineffective" as descriptive terms for virtual facets. In a pitch black room all facets are ineffective it doesn't tell me anything about another lighting where some might be effective or where these facets draw light from.

Mush is the result of small virtual facets, long light paths, and partial leakage. The mushy regions are partial leakage mixed with low angle light (greenish white or whitish green in ASET), high angle light (reddish white) or facets that draw light just under the girdle (greyish white). Photographs are not the best for observing leakage especially grey background ones as you can't differentiate between the shades of grey.

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

 

[Texas Leaguer]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg,
Can you help me understand the role of dispersion in creating colors in ASET other than red,green and blue? I am confused in this discussion between the additional colors caused by mixing of VF layers and that caused by dispersion.
As an example, I am hearing that yellow in CG ASET can be caused by mixing of red and green and also by dispersion. It can also be caused in actual ASET photos by body color and enhanced by path length and leakage. (For the sake of clarity I would like to focus on CG).

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg,
Can you help me understand the role of dispersion in creating colors in ASET other than red,green and blue? I am confused in this discussion between the additional colors caused by mixing of VF layers and that caused by dispersion.
As an example, I am hearing that yellow in CG ASET can be caused by mixing of red and green and also by dispersion. It can also be caused in actual ASET photos by body color and enhanced by path length and leakage. (For the sake of clarity I would like to focus on CG).

Bryan,

lets consider just R, G, B lengthways ( for simplification)

Red, Blue, Green lengthways produce different Vf's. but because dispersion angle inside diamond is too small and length pass inside diamond is just few mm then we do not see the difference in boundaries between Red, Blue, Green Vf's.
angular dispersion is much higher outside diamond . for example if angle between red and green rays is 1 degree , It gives 0.2mm difference for lengthpass 12mm.
so green ray would come to green ASET, Red ray reach red ASET. Or both rays come to boundary between ASET red and green zones which would be yellow due technical limitations.
in both cases you will see yellow VF.
if ASET has bigger diameter then distance between Red and Green rays is bigger and probability to see yellow VF's is bigger too . I think ASG used desktop ASET version for photos in article.

 

[Texas Leaguer]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg,
Can you help me understand the role of dispersion in creating colors in ASET other than red,green and blue? I am confused in this discussion between the additional colors caused by mixing of VF layers and that caused by dispersion.
As an example, I am hearing that yellow in CG ASET can be caused by mixing of red and green and also by dispersion. It can also be caused in actual ASET photos by body color and enhanced by path length and leakage. (For the sake of clarity I would like to focus on CG).

Bryan,

lets consider just R, G, B lengthways ( for simplification)

Red, Blue, Green lengthways produce different Vf's. but because dispersion angle inside diamond is too small and length pass inside diamond is just few mm then we do not see the difference in boundaries between Red, Blue, Green Vf's.
angular dispersion is much higher outside diamond . for example if angle between red and green rays is 1 degree , It gives 0.2mm difference for lengthpass 12mm.
so green ray would come to green ASET, Red ray reach red ASET. Or both rays come to boundary between ASET red and green zones which would be yellow due technical limitations.
in both cases you will see yellow VF.
if ASET has bigger diameter then distance between Red and Green rays is bigger and probability to see yellow VF's is bigger too . I think ASG used desktop ASET version for photos in article.

Thank you for that. I think I am starting to get it.

Here's a related question; the RBC in the AGS article shows alot of yellow (actual photo). Based upon what I just learned I would not expect that since the desktop ASET hemisphere is quite small (looks to be about 3" diameter). And that is quite a bit smaller than the theoretical basis for the AGS LP system which models a hemisphere of 9.85" to simulate a viewing distance of "most distinct vision". Yet the actual photo shows yellow and the CG does not. What might account for the differences?

 

[Karl_K]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg,
Can you help me understand the role of dispersion in creating colors in ASET other than red,green and blue? I am confused in this discussion between the additional colors caused by mixing of VF layers and that caused by dispersion.
As an example, I am hearing that yellow in CG ASET can be caused by mixing of red and green and also by dispersion. It can also be caused in actual ASET photos by body color and enhanced by path length and leakage. (For the sake of clarity I would like to focus on CG).

Bryan,

lets consider just R, G, B lengthways ( for simplification)

Red, Blue, Green lengthways produce different Vf's. but because dispersion angle inside diamond is too small and length pass inside diamond is just few mm then we do not see the difference in boundaries between Red, Blue, Green Vf's.
angular dispersion is much higher outside diamond . for example if angle between red and green rays is 1 degree , It gives 0.2mm difference for lengthpass 12mm.
so green ray would come to green ASET, Red ray reach red ASET. Or both rays come to boundary between ASET red and green zones which would be yellow due technical limitations.
in both cases you will see yellow VF.
if ASET has bigger diameter then distance between Red and Green rays is bigger and probability to see yellow VF's is bigger too . I think ASG used desktop ASET version for photos in article.

Thank you for that. I think I am starting to get it.

Here's a related question; the RBC in the AGS article shows alot of yellow (actual photo). Based upon what I just learned I would not expect that since the desktop ASET hemisphere is quite small (looks to be about 3" diameter). And that is quite a bit smaller than the theoretical basis for the AGS LP system which models a hemisphere of 9.85" to simulate a viewing distance of "most distinct vision". Yet the actual photo shows yellow and the CG does not. What might account for the differences?

girdle plane difference? in the desktop scope the diamond is sitting on the table vs a calculation of the girdle plane on the CG. Scan errors is another possibility.

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg,
Can you help me understand the role of dispersion in creating colors in ASET other than red,green and blue? I am confused in this discussion between the additional colors caused by mixing of VF layers and that caused by dispersion.
As an example, I am hearing that yellow in CG ASET can be caused by mixing of red and green and also by dispersion. It can also be caused in actual ASET photos by body color and enhanced by path length and leakage. (For the sake of clarity I would like to focus on CG).

Bryan,

lets consider just R, G, B lengthways ( for simplification)

Red, Blue, Green lengthways produce different Vf's. but because dispersion angle inside diamond is too small and length pass inside diamond is just few mm then we do not see the difference in boundaries between Red, Blue, Green Vf's.
angular dispersion is much higher outside diamond . for example if angle between red and green rays is 1 degree , It gives 0.2mm difference for lengthpass 12mm.
so green ray would come to green ASET, Red ray reach red ASET. Or both rays come to boundary between ASET red and green zones which would be yellow due technical limitations.
in both cases you will see yellow VF.
if ASET has bigger diameter then distance between Red and Green rays is bigger and probability to see yellow VF's is bigger too . I think ASG used desktop ASET version for photos in article.

Thank you for that. I think I am starting to get it.

Here's a related question; the RBC in the AGS article shows alot of yellow (actual photo). Based upon what I just learned I would not expect that since the desktop ASET hemisphere is quite small (looks to be about 3" diameter). And that is quite a bit smaller than the theoretical basis for the AGS LP system which models a hemisphere of 9.85" to simulate a viewing distance of "most distinct vision". Yet the actual photo shows yellow and the CG does not. What might account for the differences?

as I remember ASG patent for "raytracing ", they used many tricks to do "fast" calculations.
Most probably they use just one lengthwave for each pixel( in other words they did not use dispersion to calculate ASET images)
better too ask ASG developers. I have not enough information about ASG software.

 

[Texas Leaguer]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg,
Can you help me understand the role of dispersion in creating colors in ASET other than red,green and blue? I am confused in this discussion between the additional colors caused by mixing of VF layers and that caused by dispersion.
As an example, I am hearing that yellow in CG ASET can be caused by mixing of red and green and also by dispersion. It can also be caused in actual ASET photos by body color and enhanced by path length and leakage. (For the sake of clarity I would like to focus on CG).

Bryan,

lets consider just R, G, B lengthways ( for simplification)

Red, Blue, Green lengthways produce different Vf's. but because dispersion angle inside diamond is too small and length pass inside diamond is just few mm then we do not see the difference in boundaries between Red, Blue, Green Vf's.
angular dispersion is much higher outside diamond . for example if angle between red and green rays is 1 degree , It gives 0.2mm difference for lengthpass 12mm.
so green ray would come to green ASET, Red ray reach red ASET. Or both rays come to boundary between ASET red and green zones which would be yellow due technical limitations.
in both cases you will see yellow VF.
if ASET has bigger diameter then distance between Red and Green rays is bigger and probability to see yellow VF's is bigger too . I think ASG used desktop ASET version for photos in article.

Thank you for that. I think I am starting to get it.

Here's a related question; the RBC in the AGS article shows alot of yellow (actual photo). Based upon what I just learned I would not expect that since the desktop ASET hemisphere is quite small (looks to be about 3" diameter). And that is quite a bit smaller than the theoretical basis for the AGS LP system which models a hemisphere of 9.85" to simulate a viewing distance of "most distinct vision". Yet the actual photo shows yellow and the CG does not. What might account for the differences?

girdle plane difference? in the desktop scope the diamond is sitting on the table vs a calculation of the girdle plane on the CG. Scan errors is another possibility.

That's a good point. There would be no green coming in from the girdle line to the crown. But it would also push the girdle plane away from the blue boundary and the two images look pretty consistent in terms of blue. (?)

 

[Texas Leaguer]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg,
Can you help me understand the role of dispersion in creating colors in ASET other than red,green and blue? I am confused in this discussion between the additional colors caused by mixing of VF layers and that caused by dispersion.
As an example, I am hearing that yellow in CG ASET can be caused by mixing of red and green and also by dispersion. It can also be caused in actual ASET photos by body color and enhanced by path length and leakage. (For the sake of clarity I would like to focus on CG).

Bryan,

lets consider just R, G, B lengthways ( for simplification)

Red, Blue, Green lengthways produce different Vf's. but because dispersion angle inside diamond is too small and length pass inside diamond is just few mm then we do not see the difference in boundaries between Red, Blue, Green Vf's.
angular dispersion is much higher outside diamond . for example if angle between red and green rays is 1 degree , It gives 0.2mm difference for lengthpass 12mm.
so green ray would come to green ASET, Red ray reach red ASET. Or both rays come to boundary between ASET red and green zones which would be yellow due technical limitations.
in both cases you will see yellow VF.
if ASET has bigger diameter then distance between Red and Green rays is bigger and probability to see yellow VF's is bigger too . I think ASG used desktop ASET version for photos in article.

Thank you for that. I think I am starting to get it.

Here's a related question; the RBC in the AGS article shows alot of yellow (actual photo). Based upon what I just learned I would not expect that since the desktop ASET hemisphere is quite small (looks to be about 3" diameter). And that is quite a bit smaller than the theoretical basis for the AGS LP system which models a hemisphere of 9.85" to simulate a viewing distance of "most distinct vision". Yet the actual photo shows yellow and the CG does not. What might account for the differences?

as I remember ASG patent for "raytracing ", they used many tricks to do "fast" calculations.
Most probably they use just one lengthwave for each pixel( in other words they did not use dispersion to calculate ASET images)
better too ask ASG developers. I have not enough information about ASG software.

Interesting. I will see if I can find out. I do know that they had to make some decisions on how far to take the analysis, considering the limits of computing power at the time the system was developed. I heard that a ray trace would take about 20 minutes when the system was launched and it takes something like 6 seconds today. I may be off in my recollection on the specifics but I'm sure you get the point and have experienced the same.

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg,
Can you help me understand the role of dispersion in creating colors in ASET other than red,green and blue? I am confused in this discussion between the additional colors caused by mixing of VF layers and that caused by dispersion.
As an example, I am hearing that yellow in CG ASET can be caused by mixing of red and green and also by dispersion. It can also be caused in actual ASET photos by body color and enhanced by path length and leakage. (For the sake of clarity I would like to focus on CG).

Bryan,

lets consider just R, G, B lengthways ( for simplification)

Red, Blue, Green lengthways produce different Vf's. but because dispersion angle inside diamond is too small and length pass inside diamond is just few mm then we do not see the difference in boundaries between Red, Blue, Green Vf's.
angular dispersion is much higher outside diamond . for example if angle between red and green rays is 1 degree , It gives 0.2mm difference for lengthpass 12mm.
so green ray would come to green ASET, Red ray reach red ASET. Or both rays come to boundary between ASET red and green zones which would be yellow due technical limitations.
in both cases you will see yellow VF.
if ASET has bigger diameter then distance between Red and Green rays is bigger and probability to see yellow VF's is bigger too . I think ASG used desktop ASET version for photos in article.

Thank you for that. I think I am starting to get it.

Here's a related question; the RBC in the AGS article shows alot of yellow (actual photo). Based upon what I just learned I would not expect that since the desktop ASET hemisphere is quite small (looks to be about 3" diameter). And that is quite a bit smaller than the theoretical basis for the AGS LP system which models a hemisphere of 9.85" to simulate a viewing distance of "most distinct vision". Yet the actual photo shows yellow and the CG does not. What might account for the differences?

as I remember ASG patent for "raytracing ", they used many tricks to do "fast" calculations.
Most probably they use just one lengthwave for each pixel( in other words they did not use dispersion to calculate ASET images)
better too ask ASG developers. I have not enough information about ASG software.

Interesting. I will see if I can find out. I do know that they had to make some decisions on how far to take the analysis, considering the limits of computing power at the time the system was developed. I heard that a ray trace would take about 20 minutes when the system was launched and it takes something like 6 seconds today. I may be off in my recollection on the specifics but I'm sure you get the point and have experienced the same.

We never used pixel raytracing early , because it demands very powerful graphic processors( GPU). such processor just coming.
We use beam( cone) raytracing. it is much faster if you have not very powerful GPU.
now both methods give similar speed because GPU become very powerful . of course this speed is much faster than 6 seconds if you use good raytracing algorithm . 6 seconds are enough to calculate diamonds image with all main lens limitations ( as finite depth of focus)

 

[MelisendeDiamonds]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg I have collected a pretty big library of scans of proprietary brilliant cut stones over the years, probably in the hundreds.
I see few if any examples of large VFs being the mixed color yellow or understand what you are referring to when you say multilayer VF structure.

The times I've seen yellow have been:

1) Overemphasized Dispersion In Diamcalc not seen in a handheld view
2) Glare or errant lighting
3) Absorption from colored material
4) Dispersion (but usually from smaller Vfs)

Any examples?

 

[Garry H (Cut Nut)]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

Correct. I think if you check that stone you could find there is a blue dispersion escaping, leaving yellow as in this e.g.

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

And what will be the effect of turning dispersion off vs. on in the DC ASET?

You won't see the yellow and purple anymore.

VF's have multilayer structure .
VF's from different layers but with joint area in table projection would catch different ASET colours.
Cuts as RBC have strong dominated VF's with total brightness above 65%, it is reason why yellow is so rare in RBC.
but cut without dominated VF's would produce yellow even for material with zero dispersion

Serg I have collected a pretty big library of scans of proprietary brilliant cut stones over the years, probably in the hundreds.
I see few if any examples of large VFs being the mixed color yellow or understand what you are referring to when you say multilayer VF structure.

The times I've seen yellow have been:

1) Overemphasized Dispersion In Diamcalc not seen in a handheld view
2) Glare or errant lighting
3) Absorption from colored material
4) Dispersion (but usually from smaller Vfs)

Any examples?

Melisende,

1)specially for you I have just checked MSS data( just 20 diamonds).
see example. Do you see pure Red , Green, Blue and Purple-Violet, Brown( Dark Yellow) , Carrot-Red VF's?
Is it enough to proof my statements about multilayers VF's structure?
2) 5-10 years ago when I studied ASET , I saw several example with high saturated Yellow. It is rare in RBC ASET but happened .
I advice you to stop spend time for ASET discussions. Importance ASET will less and less each next years. Consumers and trade will use high quality movies in normal light to select diamonds. ( many such systems( from different companies) are coming to market now. B2B become use its).
Sorry , It is to boring all ASET discussion for me. ( just waste time)
3) But if you want select diamonds buy ASET, we also give such option a soon.

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

MSS18

Do you see in this sample the VF with mixed green and red colours?

 

[MelisendeDiamonds]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

MSS18

Do you see in this sample the VF with mixed green and red colours?

I can't reproduce the "Yellowish Reddish Green" appearance in that photographed ASET in DC unless I turn on dispersion.
But it does seem the rays which exit there have some higher angle sources as well as lower angle.

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

MSS18

Do you see in this sample the VF with mixed green and red colours?

I can't reproduce the "Yellowish Reddish Green" appearance in that photographed ASET in DC unless I turn on dispersion.
But it does seem the rays which exit there have some higher angle sources as well as lower angle.

would you explain Your goal for these questions?

.

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

BTW.

Yellow is Best colour in ASET photos ( better than Green , Red) .

Yellow ASET cuts would have better Life than Red/Green cuts.

 

[Texas Leaguer]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

BTW.

Yellow is Best colour in ASET photos ( better than Green , Red) .

Yellow ASET cuts would have better Life than Red/Green cuts.

That is a really interesting statement Serg. Can you expound on that a little bit? Is that because the yellow indicates higher levels of dispersion?

 

[Serg]

Re: An interesting (to me) ASET comparison -- JA vs. DiamCal

BTW.

Yellow is Best colour in ASET photos ( better than Green , Red) .

Yellow ASET cuts would have better Life than Red/Green cuts.

That is a really interesting statement Serg. Can you expound on that a little bit?

Bryan,

Such cut design had not develop yet. It is very very difficult in mono. ( Cyclope ASET).

in standard design :
1) first reflection has intensity 17-18%
2) First outgoing beam-67%
3) Second outgoing beam -12%

unknown way to receive 40-50% for first outgoing way instead 67% for tilting diamond( it is easy if we freeze diamond and eye position, but it is not practical solution)
but if for example 1st beam has angle 20 degree, 3d has angle 40 degree and 2d has angle 60-70 degree then

single diamond zone would catch lights sources from 3 different directions in same time and produce relative bright flashes.
so such zone has high probability to produce flashes( much more than even RBC)
if a diamond has many such zones than the diamond has a lot of flashes in same time.( and yellowish colour in ASET )

we tried to find such design several times but without success yet.

in Stereo it has to be more easy , but also very difficult .