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Andrew C on Mozilla nous apporta ses lumieres ainsi en ce 2004/05/09
05:54... :
> Hi folks.
>
> This is supposed to be a an extreme closeup of a small gemstone (a few
> mm across), set in a gold setting. But it looks nothing like that -
> and I can't figure out why.
>
> The stone doesn't look remotely gem-like. Can't figure that out. It's
> transparent, reflective, and reflective. What am I missing?
>
> The setting doesn't look like gold. I've fiddled with brilliance,
> specular, roughness, reflection, and turned on metallic (as well as
> conserve_energy). Still doesn't look remotely like metal. Why?
>
> Also can't figure out why the metal setting apparently isn't resulting
> in any photons. (It makes the photon process hundreds of times slower
> - that is, I had to multiply the photon spacing a few hundred times to
> get it to render this year.)
>
> This was supposed to end up being a single link in a bracelet - but it
> looks so rubbish I hadn't get that far yet.
>
> Any ideas?
> Andrew @ home.
>
>
> ------------------------------------------------------------------------
>
The IOR for your gem may be to low, ruby's ior is higher than glass,
close to 2 I think. Did you set the fade_distance and fade_power? Do you
use media_atenuation? Sould be on. Now, it look like only the surfaces
have any colour.
This look like a midle-ages kind of cut, no faceting on the under side,
very box like (the had still to develop the needed skils and tools).
Did you set the metal as a target for the photons?
It may be "good enough" as is if it's going to be small in the final
scene. How many links in your bracelet? How large will be the complete
bracelet in your scene? You may do a trial render of the complete
bracelet at the planed scale (no protons, no radiosity, no aa, only 1 or
2 light).
Alain
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> The IOR for your gem may be to low, ruby's ior is higher than glass,
> close to 2 I think.
Ruby = 1.7 according to the reference I saw - which happens to be what
I'm using, by total fluke ;-)
> Did you set the fade_distance and fade_power?
Don't even know what those do without checking the manual... LOL!
> Do you use media_atenuation? Sould be on.
Ditto.
> Now, it look like only the surfaces have any colour.
True.
> This look like a midle-ages kind of cut, no faceting on the under side,
> very box like (the had still to develop the needed skils and tools).
...guess whic POV-Ray primitive I used to make it? ;-)
But yes, it seems I need more cuts. Pitty - they are really hard to do. :-S
> Did you set the metal as a target for the photons?
Yup. Target on, collect off, reflection on, refraction off.
> It may be "good enough" as is if it's going to be small in the final
> scene.
No - it's going to BE the entire scene. Or that's the plan...
Anyway, thanks for the tips...
Andrew @ home.
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Andrew C on Mozilla wrote:
>
>>> Anyone know where I can find technical drawings with measurements?
>>
>>
>> Try his link http://www.3dlapidary.com/Home.htm it could of help. They
>> got a
>> lot of free *.dxf models of gemsone cuts.
>
>
> Yes - I already found this by Googling.
>
> Trouble is... what the hell is a DXF file??
>
> Andrew @ home.
Autocad
fairly well detailed structure is around (google time), not sure if its
version specific though
stephen
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> Trouble is... what the hell is a DXF file??
>
I think Crossroads may convert DXF to POVRay, but I downloaded the "RAW"
format from 3dLapidary. This just lists the vertices, and by playing
with the file -- IIRC inserting commas, "<" ">" and "triangle" you can
create a MESH1 object out of it.
I'm trying to recall off the top of my head, since my files like this
are at home, but it must have been pretty simple, or else I never could
have managed it.
Dave Matthews
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Andrew C on Mozilla nous apporta ses lumieres ainsi en ce 2004/05/09
11:41... :
>> The IOR for your gem may be to low, ruby's ior is higher than glass,
>> close to 2 I think.
>
>
> Ruby = 1.7 according to the reference I saw - which happens to be what
> I'm using, by total fluke ;-)
>
>> Did you set the fade_distance and fade_power?
>
>
> Don't even know what those do without checking the manual... LOL!
They set the rate at witch the light is absorbed.
Start with fade_distance 1 and fade_power 2 (real world value) can also
use 1001, then change fade_distance until you are satisfied.
>
>> Do you use media_atenuation? Sould be on.
>
>
> Ditto.
The ticker the object, stronger the colouring get. Boolean, on or off. I
think that it's ON by default.
>
>> Now, it look like only the surfaces have any colour.
>
>
> True.
fade_distance and fade_power are usefull for that. It simulate the
inside's colouring.
>
>> This look like a midle-ages kind of cut, no faceting on the under
>> side, very box like (the had still to develop the needed skils and
>> tools).
>
>
> ...guess whic POV-Ray primitive I used to make it? ;-)
difference of boxes
>
> But yes, it seems I need more cuts. Pitty - they are really hard to
> do. :-S
>
>> Did you set the metal as a target for the photons?
>
>
> Yup. Target on, collect off, reflection on, refraction off.
>
>> It may be "good enough" as is if it's going to be small in the final
>> scene.
>
>
> No - it's going to BE the entire scene. Or that's the plan...
>
> Anyway, thanks for the tips...
>
> Andrew @ home.
Alain
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I downloaded a zip file of loads of gem meshes, pretty much all the cuts you
might want. I got the link from a post here sometime last year but I can't
remember now who or when, sorry.
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Dave Matthews wrote:
> I'm trying to recall off the top of my head, since my files like this
> are at home, but it must have been pretty simple, or else I never could
> have managed it.
>
Well, for the record, here's what I did:
First, I opened the raw (txt) file in Microsoft Word (sorry, but I did.)
By using "find" and "replace all" I added commas after each vertex.
(Is there some way of doing this in POV SDL? I couldn't think of any.)
Then, once it was comma-delimited, I could use the following POV
script to create a mesh1 object:
//------------------------------------------------------------------------
//This creates a Mesh1 object include file
#fopen Converted_File "MESHFILE.inc" write
//This should be the comma-delimited RAW format file
#fopen Raw_File "RAWFILE.txt" read
//Here's where you name your mesh object
#write(Converted_File, "#declare MESH_OBJECT = object { \n")
//This stuff creates the mesh
#write(Converted_File, "mesh { \n" )
#read (Raw_File,X_1,Y_1,Z_1)
#while (defined(Raw_File))
#write(Converted_File, "triangle { ")
#write(Converted_File, "<" , X_1, ", "Y_1, ", " Z_1, ">, ")
#read (Raw_File,X_2,Y_2,Z_2)
#write(Converted_File, "<" , X_2, ", "Y_2, ", " Z_2, ">, ")
#read (Raw_File,X_3,Y_3,Z_3)
#write(Converted_File, "<" , X_3, ", "Y_3, ", " Z_3, "> } \n ")
#read (Raw_File,X_1,Y_1,Z_1)
#end
#write(Converted_File, " } \n ")
#write(Converted_File, "}; \n" )
#fclose Converted_File
//Then if you want to use it, you do something like this:
#include "MESHFILE.inc"
#declare NEW_OBJECT = MESH_OBJECT;
object { NEW_OBJECT texture { pigment { color rgb <1, 0, 0> } } }
//
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On Sun, 09 May 2004 10:54:43 +0100, Andrew C on Mozilla <voi### [at] dev null>
wrote:
> Hi folks.
>
> This is supposed to be a an extreme closeup of a small gemstone (a few
> mm across), set in a gold setting. But it looks nothing like that - and
> I can't figure out why.
>
> The stone doesn't look remotely gem-like. Can't figure that out. It's
> transparent, reflective, and reflective. What am I missing?
>
> The setting doesn't look like gold. I've fiddled with brilliance,
> specular, roughness, reflection, and turned on metallic (as well as
> conserve_energy). Still doesn't look remotely like metal. Why?
>
> Also can't figure out why the metal setting apparently isn't resulting
> in any photons. (It makes the photon process hundreds of times slower -
> that is, I had to multiply the photon spacing a few hundred times to get
> it to render this year.)
>
> This was supposed to end up being a single link in a bracelet - but it
> looks so rubbish I hadn't get that far yet.
>
I was playing with isosurfaces some while back and produced this if it
helps:
//start code
#include "glass.inc"
#include "textures.inc"
global_settings{
photons{count 10000}
}
camera{
location <-2,5,-5>
look_at 0}
plane{y,-2 pigment{
agate scale 20 color_map{[0 rgb 0.5][1 rgb 1]} }}
light_source{<0,10,10> rgb 1
photons{reflection on refraction on}
}
#declare RubyFace=
isosurface {
function {max(abs(x)+abs(y)-3
,abs(z)+abs(y)-3
,abs(x)+abs(y)+abs(z)-4
)}
contained_by {box{-2, 2}}
max_gradient 2
scale y*0.5
}
#declare RubyHalf=
difference{
object{RubyFace}
box{-3,<3,0.2,3>}
translate y*-0.201
}
merge{
object{RubyHalf}
object{RubyHalf scale <1,-1,1>}
pigment{Col_Glass_Ruby}
finish{specular 0.5 reflection 0.2}
interior{ior 1.7}
photons{target refraction on reflection on}
}
#declare i=-13;
#declare Beads=
union{
#while(i<14)
sphere{0,0.1 texture{Gold_Metal} translate <-2.1,0.2,i*0.1>}
#declare i=i+1;
#end
}
#declare BeadBand=
union{
object{Beads}
object{Beads scale y*-1}
box{0,<0.2,0.2,2.8> texture{Gold_Metal} translate <2,-0.1,-1.4>}
}
object{BeadBand}
object{BeadBand scale x*-1}
//end code
The underside facets make a big difference
--
Phil Cook
--
All thoughts and comments are my own unless otherwise stated and I am
happy to be proven wrong.
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Alain <aze### [at] qwertygov> wrote:
> The IOR for your gem may be to low, ruby's ior is higher than glass,
> close to 2 I think. Did you set the fade_distance and fade_power?
The IOR for Ruby is 1.76 and 1.768.
// CORUNDUM
// Variety: Ruby
// Variety: Sapphire
#declare Corundum_IOR_e_1 = 1.76;
#declare Corundum_IOR_w_1 = 1.768;
#declare Corundum_Birefringence_1 = 0.0080;
If you need more IOR values, take a look at my old NewIOR.inc file available
at http://seasoft.tecbox.com/Pov/NewIOR.html with IOR values for almost
3000 minerals. It also includes severals gemstone cuts in POV-Ray format.
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Sven-Erik Andersen nous apporta ses lumieres ainsi en ce 2004/05/16
15:25... :
>Alain <aze### [at] qwertygov> wrote:
>
>
>>The IOR for your gem may be to low, ruby's ior is higher than glass,
>>close to 2 I think. Did you set the fade_distance and fade_power?
>>
>>
>
>The IOR for Ruby is 1.76 and 1.768.
>
>// CORUNDUM
>// Variety: Ruby
>// Variety: Sapphire
>#declare Corundum_IOR_e_1 = 1.76;
>#declare Corundum_IOR_w_1 = 1.768;
>#declare Corundum_Birefringence_1 = 0.0080;
>
>If you need more IOR values, take a look at my old NewIOR.inc file available
>at http://seasoft.tecbox.com/Pov/NewIOR.html with IOR values for almost
>3000 minerals. It also includes severals gemstone cuts in POV-Ray format.
>
>
>
>
Thanks, it will help everybody to make better POV Ray gems.
I know, I over-estimated ruby's ior, but I don't have the adequate
refferences on hand.
Alain
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