Author Topic: corona "vs" redshift  (Read 20235 times)

2015-01-17, 16:16:11

piripi

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Dear everybody,

(jpg is compressed with 65%, but max file size is 1,5mb sorry)

just want to share my naive comparison test between amazing corona 7.2 and fantastic redshift V0.1.10 Alpha for Max.

Hardware:
i7 4930k @ 4,3ghz
Asus GTX 780 6GB (latest driver of NVIDIA)
32 GB Ram
win 8.1

first i want to point out, that this is NO “mac vs pc”,  “android vs iphone”  discussion…

its just a personal test i did this morning to see which render engine i could/should use for each project, or in which i should invest first in near future… (ciao ciao free public alpha)

i didn’t speed much time on the materials, i just tried to match it as close as i could in 5 min…
i’m very new to redshift, so the material conversion is not the best… and i don’t know how to translate the Fresnel from corona / vray to the “same” value in “facing bla bla ...” and “curve falloff”.

i used the same bitmap texture for “reflection color” and “reflection glossiness”.
i had the impression that, the corona looked more blurred, with the same texute, so i adjusted it a bit…

is there a way to convert this values better?

the lights are all corona / redhsift native area-lights, the size, color and intensity are equal.

hope this is interesting for you guys, again, BOTH render engines are amazing!!

i would be happy if somebody could point out, how to convert fresnel to redshift values, is there a simple rule / calculation?

my personal conclusion:
both are super cool, its really depending what you are going for…
after this test redshift would be my choice for animation and
corona for archvis, i’m sure both can be accomplished vis a vis

cheers
piripi

p.s. after finishing the renderpart, i realized its just 800px resoluion :( 
if someone is interested in the exr files let me know

2015-01-17, 17:11:01
Reply #1

borisquezadaa

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What version of Corona did you use for comparation?.
Also very simple scene to be conclusive.
What i do with Corona My Corona post of random stuff rendering
WARNING: English.dll still loading...

2015-01-17, 17:15:53
Reply #2

piripi

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7.2 public

2015-01-17, 17:50:05
Reply #3

Juraj

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Interesting :- ) Continue please.

Now you could move to some more complex (GI involving) scene.

Few websites btw state both fresnel IOR and Incidence angle reflectance (0° to 90°), I've even seen some calculator somewhere though can't remember where.
The most common non-metallic shader has frontal reflectance of 0.04, which corresponds to 1.52 IOR.

http://refractiveindex.info/ {angle of incidence is in top lowest graph}

Hey, can you post a screenshot of their shader UI in Max ?

http://docs.redshift3d.com/Default.html#I/Architectural.html

Interesting, they made their own Mix of Vray-ish (Roughness is dusty-ness and glossiness is roughness) with Maxwell (full fresnel n & K formula) down to PBR (Metal-ness which automatically decides whether to use color for specular or diffuse reflection).
It seems quite strange, but pretty robust. Everyone feels the need to re-invent wheel..
« Last Edit: 2015-01-17, 17:58:17 by Juraj_Talcik »
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2015-01-17, 18:07:03
Reply #4

piripi

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both materials

thanks for the explanation, i'll try to make it work
« Last Edit: 2015-01-17, 18:21:11 by piripi »

2015-01-17, 19:00:35
Reply #5

piripi

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redshift related:
AHA, just found out, that if i change the IOR in refraction it has effects to the reflection, sorry this may sound stupid for people how know physics better than me ;)

or is there s simple way to convert ior to k? is this the same? confused...

2015-01-17, 19:26:36
Reply #6

DeadClown

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Those guys never think of the poor people who are doing conversion scripts. You can't convert material settings like these! But maxwell, fry, etc... are worse ;)
Any sufficiently advanced bug is indistinguishable from a feature.

2015-01-17, 19:38:58
Reply #7

piripi

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still confused ;)
but helps little bit:
quote of Adrian in reshiftforum:
https://www.redshift3d.com/forums/viewthread/3968/
Quote
By default RS the fresnel effect is computed as a dielectric index of refraction and of course by changing the index of refraction you change the reflection. I think the default fresnel should be conductor not dielectric since most of the time we create solid surfaces and metals which act as conductors not glass and water that are dielectrics.

Just switch the fresnel from dielectric to conductor and set the appropriate value for the coefficient of extinction.

Cheers

A

2015-01-17, 20:04:06
Reply #8

Juraj

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That's pretty confusing explanation. Dielectric materials are also solids, not just liquids and gases and in CGI, we mostly created solids which are dielectric in nature (porcelain, plastics,etc..) not solids which are conductors (metals). Point is, both can be in solid form..

That's why "artist-friendly" developers (Like...Disney...) created far more logical division. Metals and Non-Metals. Metals (conductors) have specular reflection property that is best represented by complex Fresnel formula, including 'Refractive index' n and 'extinction coefficient' K. Dielectrics can be for CGI purpose represented completely fine with Schlick approximation (K is consider =1)

TL:DR Quick example: {Refractiveindex.org now has special category for 3D Artists !)

Plastic (PMMA): Dielectric material, IOR (n) = 1.49 {which is equal to frontal facing reflectance =0.38}
Aluminium : Conductor, IOR (n) = 1.07 K= 6.67 {cannot be input directly in Schlick models like Vray/Corona; Frontal reflectance = 0.9 }


All in, all out, the architectural shader in Redshift is extremely stupid and best example how engineers/programmers can't think of artist. Too bad because the engine looks great.

But let's go back to topic and post some comparisons ;- )
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2015-01-17, 20:14:48
Reply #9

Ondra

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As Juraj said.

Materials such as wood, plastic, plaster, paint, brick, concrete, fabric, etc. are from physics/optics standpoint MUCH closer to water and glass than to any metal.
Rendering is magic.
Private scene uploader | How to get minidumps for crashed/frozen 3ds Max | Sorry for short replies, brief responses = more time to develop Corona ;)

2015-01-17, 23:22:15
Reply #10

blank...

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Now do a comparison with a scene that eats 16 gigs of RAM.

2015-01-17, 23:38:16
Reply #11

Ondra

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Now do a comparison with a scene that eats 16 gigs of RAM.
Quote from: Meanwhile, some random dude over at Redshift forum
All i’m getting from those tests is that Corona needs something like 8x the rendertime to match the quality of Redshift, so i’m not at all sure why you’d want to bother with it.

These comparison threads are just doomed from the beginning ;)
Rendering is magic.
Private scene uploader | How to get minidumps for crashed/frozen 3ds Max | Sorry for short replies, brief responses = more time to develop Corona ;)

2015-01-17, 23:44:31
Reply #12

piripi

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Sharing is caring ;)

2015-01-20, 14:24:43
Reply #13

Fibonacci

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Hi,

I think this comparison is not really equal, because the Redshift is GPU-base render engine. But looks good ! :)
Holy Corona : the materials is the clue.

2015-01-20, 14:36:54
Reply #14

maru

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My car is fuelled by gas.

My car has electric engine.

Let's not compare their speed! :)