Question About Realistic Renders

Forums: Question About Realistic Renders
A public forum for discussing and asking questions about the demo version of Octane Render.
Forum rules
For new users: this forum is moderated. Your first post will appear only after it has been reviewed by a moderator, so it will not show up immediately.
This is necessary to avoid this forum being flooded by spam.

Question About Realistic Renders

Postby tsiwt » Sat Jun 24, 2017 12:29 am

tsiwt Sat Jun 24, 2017 12:29 am
Hello

I was looking at the theory behind Physical Based Renders - and I read that everything apparently has Specular and everything has Fresnel.

When I dive into the database of materials provided by octane - I see that porcelain for example is made of diffuse and glossy. So how does this resemble real life?

I want to be able to create accurate materials - I read that you need to start with correct reflectance , then roughness, albedo color

But I am not sure this workflow translates to octane.

Does anyone here has a worflow of creating realistic materials based from research the materials online ?
Haven't found anything on this subject with regards to octane + C4d'

thank you.
tsiwt
 
Posts: 2
Joined: Fri Jul 25, 2014 6:40 pm

Re: Question About Realistic Renders

Postby nuno1980 » Sat Jun 24, 2017 11:37 am

nuno1980 Sat Jun 24, 2017 11:37 am
Welcome to tsiwt. :) What's('are) your videocard(s)? Maximum how much time want you to render?


If you deserve "real life" :) then type of materials:
--> glossy materials
-mirror - diffuse 0.00; specular between 0.92 and 0.94; index of refraction 1.00; roughness 0.00; rest default
-metal - diffuse 0.00; specular 0.75; index of refraction 1.00; roughness 0.00 (if you want more roughness then increase to ~0.30); rest default
...

--> specular materials - all must have the dispersion (rainbow) because the industry can't remove "dispersion" in the glasses for eyes ;)
-clear glass - reflection 1.00; transmission 1.00; index of refraction 1.509*; dispersion cofficient 0.006*; rest default
-orange glass (example) - reflection 1.00; transmission - RGB color [R 1.00, G 0.712, B 0.00] ; index of refraction 1.509*; dispersion cofficient 0.006*; rest default
-water at 25 ºC - reflection 1.00; transmission 0.9983; index of refraction 1.3244*; dispersion cofficient 0.002407*; rest default
...

NOTICE!!: in liveDB, most specular materials are bad settings, unfortunately except submitted by (I'm) Ricardo Rodrigues. ;)

How do you set any material? - consult https://refractiveindex.info/ but I'm sorry for your bit complication :)

* - 2 formulas (convert from "abbe number" to "dispersion cofficient (= B)"; calculate from original refractive index (ior) to
ior dispersed):
Code: Select all
B = (n_d - 1)/V_d*((0.48613^2*0.65627^2)/(0.65627^2 - 0.48613^2))

F and C = F and C wavelengthes - If wavelength = 589.3 nm then should use F = 486.13 nm and C = 656.27 nm


n_d_dispersed = n_d_original - 10/3*B

B -> dispersion coefficient
n_d -> refractive index
V_d -> abbe number
n_d_dispersed - refractive index dispersed if the dispersion is enabled, for Octane Render software only


Good rendering! :)
Last edited by nuno1980 on Fri Nov 17, 2017 12:30 am, edited 2 times in total.
NOTE: I'm sorry for bad english due to mute ;)

i7-12700KF
2x16GB RAM@DDR4-3600
MSI PRO Z690-A DDR4
Zotac GF RTX 4090 NEW! <3 :mrgreen:
SSDs OCZ RD400 0.5TB and Crucial 2TB SATA3
HDD 1TB SATA2
LG BD-RE BH16NS40
PSU 1kW
CRT 21" Sony E530 :D
nuno1980
Licensed Customer
Licensed Customer
 
Posts: 723
Joined: Sat Dec 18, 2010 10:04 pm

Re: Question About Realistic Renders

Postby tsiwt » Sun Jun 25, 2017 2:17 am

tsiwt Sun Jun 25, 2017 2:17 am
Thank You Nuno1980


I am interested in the link you provided and the formula -

so basically for ethanol -

https://refractiveindex.info/?shelf=org ... age=Rheims

B =(1.3571 - 1) / 59.35 * ( .52365508707)

Reflection - 0.022956 ; refractive index - 1.357 ; dispersion coefficient 0.00315075411 ...

I am not sure how you get the RGB color and the transmission. ?


also I don't understand this part of the formula - F and C = F and C wavelengthes - If wavelength = 589.3 nm then should use F = 486.13 nm and C = 656.27 nm
what is this for?



If you had to do realistic porcelain how would yo go about it, I didn't find it in the link you provided.


thanks for all the help.
tsiwt
 
Posts: 2
Joined: Fri Jul 25, 2014 6:40 pm

Re: Question About Realistic Renders

Postby nuno1980 » Mon Jun 26, 2017 12:12 am

nuno1980 Mon Jun 26, 2017 12:12 am
tsiwt wrote:Thank You Nuno1980


If you had to do realistic porcelain how would yo go about it, I didn't find it in the link you provided.


I'm very sorry for confusion because I can't understand - you said "specular" (= reflection) in glossy material OR "specular" (material). ;)

You choose to download any thing for porcelain (glossy material) in LiveDB but unfortunately, LiveDB isn't available on demo and you can buy Octane Render standalone. ;)

I am interested in the link you provided and the formula -

so basically for ethanol -

https://refractiveindex.info/?shelf=org ... age=Rheims

B =(1.3571 - 1) / 59.35 * ( .52365508707)

Reflection - 0.022956 ; refractive index - 1.357 ; dispersion coefficient 0.00315075411 ...

I am not sure how you get the RGB color and the transmission. ?
"ethanol" specs at D = 589.3 nm (enter value of wavelength in micrometers in "refractiveindex.info" site - don't forget this SI (not nm)):
n_D - 1.3616
v_D - 59.35
transmission is same number to water (T = 0.9983)

I calculated 2 formulas...
B = (n_d - 1)/V_d*((0.48613^2*0.65627^2)/(0.65627^2 - 0.48613^2))
B = (1.3616 - 1)/59.35*((0.48613^2*0.65627^2)/(0.65627^2 - 0.48613^2))
B = 0.3616/59.35*((0.236322*0.43069)/(0.43069 - 0.23622))
B = 0.3616/59.35*(0.101738/0.19447)
B = 0.00609267*0.523155
--> B = 0.003187

n_d_dispersed = n_d_original - 10/3*B
n_d_dispersed = 1.3616 - 10/3*0.003187
--> n_d_dispersed = 1.351098

You can enter these results for specular material (ethanol) settings using Octane Render:
reflection - 1.00
transmission - 0.9983
index of refraction - 1.351098 (= n_dispersed)
dispersion coefficient - 0.003187 (= B)


Transmission - you can select "greysale color" or "RGB color" or... ;)


also I don't understand this part of the formula - F and C = F and C wavelengthes - If wavelength = 589.3 nm then should use F = 486.13 nm and C = 656.27 nm
what is this for?

wavelengthes colors:
F - ultraviolet
C - infrared
D - yellow (visible light)

But you don't change any value of "F" nor of "C" in formula - look my calculations. I'm sorry. ;)


Happy rendering! :D
NOTE: I'm sorry for bad english due to mute ;)

i7-12700KF
2x16GB RAM@DDR4-3600
MSI PRO Z690-A DDR4
Zotac GF RTX 4090 NEW! <3 :mrgreen:
SSDs OCZ RD400 0.5TB and Crucial 2TB SATA3
HDD 1TB SATA2
LG BD-RE BH16NS40
PSU 1kW
CRT 21" Sony E530 :D
nuno1980
Licensed Customer
Licensed Customer
 
Posts: 723
Joined: Sat Dec 18, 2010 10:04 pm

Re: Question About Realistic Renders

Postby nuno1980 » Mon Oct 23, 2017 4:00 pm

nuno1980 Mon Oct 23, 2017 4:00 pm
!!UDPATE!!: I've edited 2nd and 4th posts about reflection for specular materials - I'm SORRY after I investigated water, glass... in real life but I stay the corrrect values of reflection for glossy materials. ;)
NOTE: I'm sorry for bad english due to mute ;)

i7-12700KF
2x16GB RAM@DDR4-3600
MSI PRO Z690-A DDR4
Zotac GF RTX 4090 NEW! <3 :mrgreen:
SSDs OCZ RD400 0.5TB and Crucial 2TB SATA3
HDD 1TB SATA2
LG BD-RE BH16NS40
PSU 1kW
CRT 21" Sony E530 :D
nuno1980
Licensed Customer
Licensed Customer
 
Posts: 723
Joined: Sat Dec 18, 2010 10:04 pm

Return to Demo Version Questions & Discussion


Who is online

Users browsing this forum: No registered users and 16 guests

Fri Mar 29, 2024 3:11 pm [ UTC ]