POV-Ray : Newsgroups : povray.general : Inquiry: What Surface Finishes for Wood do You Recommend? Server Time: 23 Mar 2019 06:37:03 GMT
  Inquiry: What Surface Finishes for Wood do You Recommend? (Message 1 to 10 of 10)  
From: Sven Littkowski
Subject: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 11 Apr 2018 14:56:46
Message: <5ace222e$1@news.povray.org>
Hi experienced POV-Ray users,

my steamboat is made of lumber. I wonder, what surface finishes you
would usually use for wooden planks. Those are deck planks, but also the
planks on the sides of the superstructures on the decks. Online I saw
some really nice examples, some even going as far as using
specular_maps, I was reading in the photo description.

Based on your own experiences, what finishes or even normals, would you use?

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From: Norbert Kern
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 11 Apr 2018 17:00:01
Message: <web.5ace3e607d1ce9641a265c980@news.povray.org>
Sven Littkowski <I### [at] SvenLittkowskiname> wrote:
> Hi experienced POV-Ray users,
>
> my steamboat is made of lumber. I wonder, what surface finishes you
> would usually use for wooden planks. Those are deck planks, but also the
> planks on the sides of the superstructures on the decks. Online I saw
> some really nice examples, some even going as far as using
> specular_maps, I was reading in the photo description.
>
> Based on your own experiences, what finishes or even normals, would you use?



Hi Sven,

When it's coming to outdoor wood, I use this sources most -

Tim McMurdo  Capstan fnished...I promise
http://news.povray.org/povray.binaries.images/thread/%3Cweb.42efc7029ecf5192acb32c570%40news.povray.org%3E/

David El Tom  Veneer pattern
http://news.povray.org/povray.binaries.images/attachment/%3C469c80fd%40news.povray.org%3E/us-ascii

Another great wood texture is based on the isowood code of Christoph Hormann
(http://www.imagico.de/iso_wood_en.php), where I use the isosurface function for
the normal definition.

Here is an example -

#macro IW_Warp_02 (Seed, xSize, ySize, zSize)

#local SZ = (xSize+ySize)*0.5*0.1;
#local Density = 0.1;
warp {
        black_hole <xSize*0.5,0,0>, SZ
        falloff 2.5
        strength 2
        repeat <min (xSize, SZ/Density),min (ySize, SZ/Density),SZ/Density>
        turbulence <0.02,0.75,0.75>
        inverse
}
#local SZ = (xSize+ySize)*0.5*0.15;
#local Density = 0.1;
warp {
        black_hole <xSize*0.5,0,0>, SZ
        falloff 2.1
        strength 3.7
        repeat <min (xSize, SZ/Density),min (ySize,
0.7*SZ/Density),0.8*SZ/Density>
        turbulence <0,0.4,0.4>
        inverse
}

#end

#macro IW_Select_Warp (WarpNbr, Seed, xSize, ySize, zSize)

IW_Warp_02 (Seed, xSize, ySize, zSize)

#end

#macro IW_Plank_Round_CutN (Seed, xSize, ySize, zSize, Rotate, Translate, Round,
Strength, Strength2, Pigm, Fin, C_Map, WarpNbr, fn_Max_Val)

#local rd = seed (Seed);

#local fn_Max = fn_Max_Val+<0,0,0>;

#local Trsx = (rand (rd)-0.5)*Translate*xSize;
#local Trsy = (rand (rd)-0.5)*Translate*ySize;
#local Trsz = (rand (rd)-0.5)*Translate*zSize;
#local Rotx = (rand (rd)-0.5)*Rotate;
#local Roty = (rand (rd)-0.5)*Rotate;

#local fn_Wood =
function {
        pigment {
                Pigm
                color_map {
                        [0      srgb 0]
                        [1      srgb 1]
                }
                translate <Trsx,Trsy,Trsz>
                rotate Rotx*x
                rotate Roty*y
                IW_Select_Warp (WarpNbr, Seed, xSize, ySize, zSize)
        }
}

#local fn_Disp =
function {
        pigment {
                average
                pigment_map {
                        [1      function {f_noise3d (0,0,z*1.6)*0.3}
                                color_map {
                                        [0      srgb 0]
                                        [1      srgb x]
                                }
                        ]
                        [1      function {f_noise3d (0,0,-z*1.6)*0.3}
                                color_map {
                                        [0      srgb 0]
                                        [1      srgb y]
                                }
                        ]
                }
        }
}
#local fnShape  = function {f_rounded_box (x,y,z, Round, xSize*0.5, ySize*0.5,
zSize*0.5+Round)}
#local fnShape2 = function {(abs (z)-zSize*0.5)}

#local fnShapeT  = function {fnShape (x+fn_Disp (x,y,z).x, y+fn_Disp
(x,y,z).y,z+fn_Disp (x,y,z).z)}
#local fnShape2T = function {fnShape2(x+fn_Disp (x,y,z).x, y+fn_Disp
(x,y,z).y,z+fn_Disp (x,y,z).z)}
#declare fnBumpsT  = function {fn_Wood (x+fn_Disp (x,y,z).x, y+fn_Disp
(x,y,z).y,z+fn_Disp (x,y,z).z).grey}

#end

#declare P_IW_10 =
pigment {
        wood
        octaves 6
        lambda 2.5
        turbulence <0.06,0.06,0.75>
        scale      <0.02,0.02,0.3>
}

#declare Fin_W_02 =
finish {
        ambient 0
        diffuse 0.95*0.6
        brilliance 1.4
        specular 0.4
        roughness 0.02
}

#declare GammaFact = 2.2;
#declare ColorDiff = <0,0,0>;

#macro ColorCorrect (Color, Gamma, ColDiff)

rgb <pow (Color.red+ColDiff.red,Gamma),pow (Color.green+ColDiff.green,Gamma),pow
(Color.blue+ColDiff.blue,Gamma)>

#end

#declare CM_IW_02 =
color_map {
        [0      ColorCorrect (<0.949,0.792,0.514>, GammaFact, ColorDiff)]
        [0.3    ColorCorrect (<0.855,0.651,0.376>, GammaFact, ColorDiff)]
        [0.6    ColorCorrect (<0.831,0.596,0.275>, GammaFact, ColorDiff)]
        [0.9    ColorCorrect (<0.620,0.447,0.204>, GammaFact, ColorDiff)]
}

IW_Plank_Round_CutN  (17, 0.3, 1.6, 8, 2, 0, 0.018, 0.0035, 0.005, pigment
{P_IW_10 scale 1.6}, Fin_W_02, CM_IW_02, 2, 0.3)

#local T_WoodA =
texture {
        pigment {
                function {fnBumpsT (x,y,z)}
                color_map {CM_IW_02}
        }
        normal {function {fnBumpsT (x,y,z)}, -0.1 accuracy 0.004}
        finish {Fin_W_02}
}

Other wood definitions are mostly useful for inhouse applications like flooring
or furniture with more smooth surfaces and coatings. Here specularmaps can be
useful. Outdoor it seems overkill, but you have to take care of the waterline...


Norbert


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From: Alain
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 11 Apr 2018 19:16:47
Message: <5ace5f1f$1@news.povray.org>
Le 18-04-11 à 10:56, Sven Littkowski a écrit :
> Hi experienced POV-Ray users,
> 
> my steamboat is made of lumber. I wonder, what surface finishes you
> would usually use for wooden planks. Those are deck planks, but also the
> planks on the sides of the superstructures on the decks. Online I saw
> some really nice examples, some even going as far as using
> specular_maps, I was reading in the photo description.
> 
> Based on your own experiences, what finishes or even normals, would you use?
> 
> ---
> Diese E-Mail wurde von AVG auf Viren geprüft.
> http://www.avg.com
> 

Normally, the deck planks are well polished wood with some protective 
layer, usually wax in this time frame, and some kind of varnish later on.
Most of the other surfaces are painted. Those that are unpainted are 
polished and waxed.

If new or near new, the deck should have a slight normal perturbation 
that match the grain of the wood, have an ior set to that of wax (1.2 to 
1.4) and use finish level fresnel and fresnel reflection.
If older, average the above with some micronormals perturbation.

For the painted surfaces, the wood grain should still affect the normals 
to some degree. The paint do have some fresnel reflectivity. Don't 
forget to set the ior for that paint.


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From: Sven Littkowski
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 12 Apr 2018 05:38:38
Message: <5acef0de$1@news.povray.org>
Thanks for these examples, they are inspiring me.

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From: Sven Littkowski
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 12 Apr 2018 05:43:11
Message: <5acef1ef@news.povray.org>
Interesting. I never worked with these features (ior, fresnel, fresnel
reflection, micronormal perturbation) and am eager to try them out.

At the current level, the painted lumber still shows a bit of the grain,
the deck even more, but I want to add now these new features that you
mention to that.

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From: Alain
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 12 Apr 2018 17:48:49
Message: <5acf9c01@news.povray.org>
Le 18-04-12 à 01:43, Sven Littkowski a écrit :
> Interesting. I never worked with these features (ior, fresnel, fresnel
> reflection, micronormal perturbation) and am eager to try them out.
> 
> At the current level, the painted lumber still shows a bit of the grain,
> the deck even more, but I want to add now these new features that you
> mention to that.
> 
> ---
> Diese E-Mail wurde von AVG auf Viren geprüft.
> http://www.avg.com
> 

A micronormal is nothing more than some normal scaled very small. It's 
used exactly the same way as you would use regular normals. To look 
correct, it demand anti-aliasing. Without, it looks very grainy. Coupled 
with reflection, it's used to get blurred reflection.

It IOR is the index of refraction. Everything non-metallic have one, 
even if it's opaque. When light encounter a surface, it's the difference 
of the outside and inside IORs and the angle of incidence that dictate 
how much reflection there will be. The specular or phong highlights are 
really nothing more than the reflection of light source.

The ior is set in the interior block. Here are examples for water and 
generic glass :
//pure water at 20°C
interior{ior 1.33}
//generic glass
interior{ior 1.5}

Most waxes have an IOR that is slightly lower than that of water (1.2 to 
1.3). Glasses can have IORs ranging from about 1.4 all the way up to 1.8 
or slightly more. Gems can range from 1.45 to 2.45 (diamond).

To enable fresnel in the reflection, you simply add fresnel into the 
reflection block. You also need to set an ior !=1, or there will be no 
reflection. Rays that are perpendicular to the surface will have very 
little reflection and rays just grazing the surface will get fully, or 
almost fully, reflected.
finish{reflection{1 fresnel} conserve_energy }

conserve_energy is used to adjust the transmitted ray relative to the 
reflection when the reflection is not constant. Don't affect things for 
opaque surfaces.
Using fresnel reflection is essential if you want to have some realistic 
water, glass or gems.

With version 3.8, you can also have a finish level fresnel:
finish{diffuse 0.7 ambient 0.1 specular 0.5 roughness 0.001 fresnel}

Where the fresnel will affect both diffuse and specular, or phong. Here 
also, you need to have an interior block to set the material's IOR.
With versions 3.7 or less, it won't work, but probably don't cause an 
error, just have no effect.


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From: Sven Littkowski
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 17 Apr 2018 03:51:54
Message: <5ad56f5a$1@news.povray.org>
Okay, I started to add reflection, fresnel, and conserve_energy to the
wood texture. But i don't see any difference to how it was before. The
ior goes into the interior, but does solid lumber have an interior?

To allow us all to experiment a bit, I am going to put my test files
into the p.b.scene-files section. So, feel free to experiment or to
demonstrate some effects. I am eager to learn!   :-)

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From: clipka
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 17 Apr 2018 07:23:39
Message: <5ad5a0fb$1@news.povray.org>
Am 17.04.2018 um 05:51 schrieb Sven Littkowski:
> Okay, I started to add reflection, fresnel, and conserve_energy to the
> wood texture. But i don't see any difference to how it was before. The
> ior goes into the interior, but does solid lumber have an interior?

Why, yes, of course solid lumber does. Ask any woodworm ;)

No, seriously: /all/ materials have a refractive index.

In most materials -- even apparently totally opaque ones -- light /does/
enter the bulk of the object; there, it is scattered somewhat randomly a
couple of hundred times by impurities or irregularities, until it is
either absorbed or happens to find its way out again. While in the
material, light waves travel slower than in vacuum, which is what gives
it a non-unity refractive index, and does cause refraction at the
boundary, and also a bit of specular reflection.

(The internal scattering process is what causes the diffuse reflection
to be virtually completely independent of the direction of incoming
light, and the absorption process is what gives colour to the material.)

Metals are a kind of exception: There, light is indeed reflected or
absorbed directly at the boundary. Yet technically even they have a
refractive index, although theirs is a complex number.


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From: Bald Eagle
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 17 Apr 2018 14:10:00
Message: <web.5ad5ff557d1ce964c437ac910@news.povray.org>
I came across this write-up, and thought you might like to read through it, to
see the approach for constructing a general wood texture.

https://www.cs.auckland.ac.nz/~burkhard/Reports/2002_SS_JackWang.pdf


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From: Sven Littkowski
Subject: Re: Inquiry: What Surface Finishes for Wood do You Recommend?
Date: 17 Apr 2018 15:27:03
Message: <5ad61247$1@news.povray.org>
Thanks, both of you. Opening the PDF now.

I put the entire lumber test scene into the p.b.scene-files sub group:
"Wood Texture Playground"

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