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On 10/12/2010 09:27, Bidski wrote:
> The picture is made by using a mesh of 48 triangles, all with the same texture
> and the mesh itself has an interior specifying the IoR and a couple of other
> flags.
>
I did a similar cut with csg a long time ago:
(it's a 3.1 object)
http://jgrimbert.free.fr/pov/brilliant.zip
(preview here:
http://jgrimbert.free.fr/pov/objet.html
)
(object is inside a sphere of radius 1, <0,0,0> is the center of the
greatest circle)
CSG is simpler than mesh when you need an interior.
You need an environment to reflect, and raise the trace level (really
raise it, 5 is far from enough with such gem's cut)
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> Hi all,
>
> I am trying to make myself a rotating gem. I found some sample code from a
> different ray tracer program and proceeded to try and "import" it into POV-Ray.
> However, the output that I am getting is far from the intended output and I am
> at a complete loss as to what I need to do to fix it.
>
> I have included links to 4 images. The GIF file is what I am trying to achieve.
> Stone1.bmp, Stone2.bmp and Stone3.bmp and the outputs that I can get by
> modifying the specular and roughness flags but I cant get the full clarity
> throughout the picture.
>
> The picture is made by using a mesh of 48 triangles, all with the same texture
> and the mesh itself has an interior specifying the IoR and a couple of other
> flags.
>
> Can anyone suggest what I might need to do in order to get this looking right?
> (I would much prefer (detailed) pointers to answers as an answer would defeat
> the purpose of learning)
>
>
> Thanks in advance
> Bidski
>
> http://i288.photobucket.com/albums/ll167/Bidskii/diamondrot.gif
> http://i288.photobucket.com/albums/ll167/Bidskii/stone1.jpg
> http://i288.photobucket.com/albums/ll167/Bidskii/stone2.jpg
> http://i288.photobucket.com/albums/ll167/Bidskii/stone3.jpg
>
>
>
Stone1 is the closest to your intended result.
You may need to change your light's position to get optimum result.
Your camera may not be located correctly.
Any gem have an ior, diamond's ior is close to 2.5.
A gem also have variable reflection. That reflection follows the fresnel
model.
There are some specular highlights.
You need some environment. It can be as simple or complicated as you want.
You may need to adjust max_trace_level. 5 is probably way to small.
Some times, you want to see the light_source... it looks_like{...}
Very low to zero ambient and low diffuse value.
Try to add some dispersion. Stay just a little over 1.
Take a look at glass.inc to get some ideas.
When things are looking good, please use anti aliasing.
Alain
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Alain <aze### [at] qwerty org> wrote:
> Stone1 is the closest to your intended result.
> You may need to change your light's position to get optimum result.
> Your camera may not be located correctly.
> Any gem have an ior, diamond's ior is close to 2.5.
> A gem also have variable reflection. That reflection follows the fresnel
> model.
> There are some specular highlights.
> You need some environment. It can be as simple or complicated as you want.
> You may need to adjust max_trace_level. 5 is probably way to small.
> Some times, you want to see the light_source... it looks_like{...}
> Very low to zero ambient and low diffuse value.
> Try to add some dispersion. Stay just a little over 1.
> Take a look at glass.inc to get some ideas.
> When things are looking good, please use anti aliasing.
>
>
> Alain
Here is the texture and material that I am using for all of the triangles and
the mesh (material for mesh, texture for triangles).
#declare Diamond_Tex = texture
{
pigment { rgbf <1, 1, 1, 1> }
finish
{
ambient 0
diffuse 0
brilliance 0.5
specular 0.9
roughness 0.05
reflection
{
colour rgb <1, 1, 1>
0.1
fresnel on
}
conserve_energy
}
}
#declare Diamond_Mat = material
{
texture { Diamond_Tex }
interior
{
ior 2.417
caustics 1
dispersion Diamond_Dispersion // Defined in consts.inc
dispersion_samples 7
fade_power 2 // Used because POV-Ray complained about
me using refraction in the finish, said I should use fade_power and
fade_distance instead.
fade_distance 1
fade_colour colour White
}
}
I added a sphere of radius 5 centered at the origin as an evironment (just added
it) to no effect, I still get the same results as I did. I coloured it white. If
I use rgb <1, 1, 1> with a radius of 10 everything vomes up grey, with a radius
of 5 the whole screen is a complete white-wash, using rgbf/t<1, 1, 1, 1> gives
me the same results as Stone1.bmp (both with a radius of 5 or 10). If I specify
no colour the whole picture is black (can't see the gem at all). Am I doing the
right thing here for an environment?
I had already changed max_trace_level from 5 to 10 (was getting warnings about
it, 10 removed the warnings). However I further changed it to 50 and then 100,
the only change that made was that the top of the gem got brigther and at 100 it
was nearly completely white.
I ran through all the finishes and interioirs in glass.inc. All the finishes
gave results close to that of Stone3.bmp, so i kept my finish. All the interiors
gave little to no change to the one I already had.
One thing that I am noticing is that it spends a lot of time rendering the top
of the gem (the part with the most clarity in Stone1.bmp) and then it chops
through the last part in less than a second (total rendering time is 17
seconds).
Regards
Bidski
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On 12/10/2010 07:18 PM, Bidski wrote:
> One thing that I am noticing is that it spends a lot of time rendering the top
> of the gem (the part with the most clarity in Stone1.bmp) and then it chops
> through the last part in less than a second (total rendering time is 17
> seconds).
sounds like you need to play with the angle of light_source and/or camera
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Jim Holsenback <jho### [at] povrayorg> wrote:
> On 12/10/2010 07:18 PM, Bidski wrote:
> > One thing that I am noticing is that it spends a lot of time rendering the top
> > of the gem (the part with the most clarity in Stone1.bmp) and then it chops
> > through the last part in less than a second (total rendering time is 17
> > seconds).
>
> sounds like you need to play with the angle of light_source and/or camera
Ok, I have tweaked the camera angle and the light_source angle and have gotten
some different results (a little better, but still not quite there). I have
attached a picture of what I have now. (stone4.bmp).
The camera used to be
camera
{
location <0, 2.5, -6>
look_at <0, 0, 0>
}
and is now
camera
{
location <0, 0, -5>
look_at <0, 0, 0>
}
and the light_source used to be
light_source
{
<0, 0, 0>
colour rgb <1, 1, 1>
translate <65, 65, -65>
}
and is now
light_source
{
<0, 0, 0>
colour rgb <1, 1, 1>
translate <5, -5 -5>
}
Keeping in mind that I have a white of radius 5 centered on the origin, this
places the camera and the light source directly on the edge of the sphere.
Im not really sure how else to twek this now as every tweak I make from here
returns me to what I had before in stone1.bmp.
If I turn conserve_energy off it brightens the gem considerably, but doesnt
change the overall appearance much.
If I have the following inside a finish
reflection
{
colour rgb <1, 1, 1>
0.1 // What is this number doing?
fresnel on
}
Regards
Bidski
http://i288.photobucket.com/albums/ll167/Bidskii/stone4.jpg
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On 12/10/2010 10:11 PM, Bidski wrote:
> Jim Holsenback <jho### [at] povrayorg> wrote:
>> On 12/10/2010 07:18 PM, Bidski wrote:
>>> One thing that I am noticing is that it spends a lot of time rendering the top
>>> of the gem (the part with the most clarity in Stone1.bmp) and then it chops
>>> through the last part in less than a second (total rendering time is 17
>>> seconds).
>>
>> sounds like you need to play with the angle of light_source and/or camera
>
> Ok, I have tweaked the camera angle and the light_source angle and have gotten
> some different results (a little better, but still not quite there). I have
> attached a picture of what I have now. (stone4.bmp).
>
> The camera used to be
>
> camera
> {
> location <0, 2.5, -6>
> look_at <0, 0, 0>
> }
>
> and is now
>
> camera
> {
> location <0, 0, -5>
> look_at <0, 0, 0>
> }
>
> and the light_source used to be
>
> light_source
> {
> <0, 0, 0>
> colour rgb <1, 1, 1>
> translate <65, 65, -65>
> }
>
> and is now
>
> light_source
> {
> <0, 0, 0>
> colour rgb <1, 1, 1>
> translate <5, -5 -5>
> }
>
> Keeping in mind that I have a white of radius 5 centered on the origin, this
> places the camera and the light source directly on the edge of the sphere.
>
> Im not really sure how else to twek this now as every tweak I make from here
> returns me to what I had before in stone1.bmp.
>
> If I turn conserve_energy off it brightens the gem considerably, but doesnt
> change the overall appearance much.
>
> If I have the following inside a finish
>
> reflection
> {
> colour rgb <1, 1, 1>
> 0.1 // What is this number doing?
> fresnel on
> }
>
> Regards
> Bidski
>
> http://i288.photobucket.com/albums/ll167/Bidskii/stone4.jpg
>
getting there ... try something other than black background ... also I
find it helpful to have object at <0,0,0> with cam at say <0,0,-10> (or
some other suitable -z dir) with look_at <0,0,0> ... rotate x*15 angles
cam up by 15 deg then rotate y*30 goes clock-wise ... similar setup with
light_source that way it's easier (to me anyways) to keep track of where
everything is. besides the texture ... light position and cam position
(viewing angle) are most important aspect of scene setup. seems like
you're headed in the right direction.
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On 12/11/2010 12:00 AM, Jim Holsenback wrote:
thought of this picture after posting:
http://wiki.povray.org/content/File:TutImgRaytracing.gif
thought it might give you some ideas of where you need to be headed with
your setup
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Jim Holsenback <jho### [at] povrayorg> wrote:
> On 12/11/2010 12:00 AM, Jim Holsenback wrote:
> thought of this picture after posting:
>
> http://wiki.povray.org/content/File:TutImgRaytracing.gif
>
> thought it might give you some ideas of where you need to be headed with
> your setup
OMG!!!! When something tells you to that it wants comma-seperated values for its
vectors, be damn sure that you put them commas in!
I didnt realise that the program that I got the basis for this gem from doesn't
use comma-seperated values in its vectors, so none of my trangle vectors had any
commas and that was the root of all my problems!
Thank you all anyways for all of your help.
I guess I just need to tweak the texture now?
http://i288.photobucket.com/albums/ll167/Bidskii/stone5.jpg
Regards
Bidski
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> I guess I just need to tweak the texture now?
As a few people have said, you should really put a background
environment on your image - even if you don't want it in the final
product - because it will show how much more potential this image has.
An object with so much reflection and refraction is begging for it. Just
slap this sky_sphere on as a starting point and see what you think. If
you like it, there are ways to keep the background black but retain it
in the reflection and refraction of the object.
sky_sphere
{
pigment
{
gradient y
color_map
{
[0 rgb <0, 0, .1>]
[1 rgb <.4, .9, 1>]
}
scale 2
translate -y
}
}
- Slime
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Slime <pov### [at] slimelandcom> wrote:
> > I guess I just need to tweak the texture now?
>
> As a few people have said, you should really put a background
> environment on your image - even if you don't want it in the final
> product - because it will show how much more potential this image has.
> An object with so much reflection and refraction is begging for it. Just
> slap this sky_sphere on as a starting point and see what you think. If
> you like it, there are ways to keep the background black but retain it
> in the reflection and refraction of the object.
I intend to use this picture in place where it needs to have either a black or a
transparent background (can POV-Ray do transparent backgrounds?). I also intend
to use some different textures to make different gems (diamonds, emeralds,
sapphires, rubies, etc). Because of this I think its best to just keep the black
background.
What do people think about the overall look of this gem (stone5)?
Regards
Bidski
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