Messages

601

[Max] General Discussion / Re: The albedo question.

« on: 2014-03-16, 05:48:56 »

Great to hear that, i'm gonna try to understand the way Corona material works... to really understand and avoid the always neccesary "cheat".

This article is a little heavy but maybe helps me understand the basics.
http://www.scratchapixel.com/lessons/3d-advanced-lessons/things-to-know-about-the-cg-lighting-pipeline/what-is-a-brdf/

If i remember correctly 3ds max design uses some ligthing analysis that where expressed in pretty solid S.I. units (not parrots) but only for MentalRay using some Brute force aproach (unbiased?).

So i have no doubt that tuning a Corona Material we can set that LRV values at least for a solid color... the question is how.

For example 10 boxes and 10 ligths one base plane.

Default Corona White material (180 rgb white).
1.- Change "value" in diffuse (reflection, refraction 0) gives expected results.
2.- Change "color" in difusse (reflection, refraction 0) gives expected results.
3.- Change "value" in reflection (diffuse, refraction 0) gives no ligth on ground.
4.- Change "color" in reflection (diffuse, refraction 0) gives no ligth on ground.

Interesting topic the reflectance you where rigth about that 90° aproach... but here comes the fresnel to save the day.

I really need to understand the way brdf shader work.

602

[Max] General Discussion / Re: The albedo question.

« on: 2014-03-16, 02:13:39 »

Thanks for the info... is quite a subject i see.

And it seems to me that albedo and LRV are the same thing. Some kind of measure of radiation reflected respect to some radiation received.

Now lets put this stuff to a test.

603

[Max] General Discussion / The albedo question.

« on: 2014-03-16, 00:05:37 »

I guys, i have spent few days reading the forum but i still can't answer a simple question.

The corona wiki states that a cause of poor performance in rendering is caused by this:

"Too high walls albedo in an interior scene. Albedo is the percentage of energy a material reflects, and in Corona is the sum of diffuse, reflective, refractive, and translucent components. In reality almost no materials have near-white albedos, and using white albedo (for example 255-white diffuse color) in rendering gives very unrealistic and slow results, and cannot be correctly rendered with an unbiased renderer. Try keeping albedos of all your main scene objects under RGB 180, and get whiter walls by brightening light sources.

There is a table around that list common albedos for tipical materials.

It says that snow (for example) has an albedo of between 40 to 85 (depending on snow).

The question itching in the back of my head is:

Where is the albedo in the material  editor?...

The diffuse section includes a LEVEL (0-1), an rgb color and the posibility of load a texture, same for reflection and refraction.

If the albedo of a material is 0.4 do i put level to 0.4 in diffuse and leave reflection and refraction at 0 so the sum is that 0.4?
Or is the rgb that sums that way?... what if i put a texture?... and if that color in texture are way beyond "1! like an exr or hdr?...

And what happen if the material is an emitter one?... (by the way can't find the light material in A5, is present only in dailys?).

Hope some one can share wisdom.

604

[Max] General Discussion / Info on fireflies supressión

« on: 2014-03-15, 19:16:59 »

I just read this in the RandomControl forum respect to fireflies supression.

http://randomcontrol.com/blog/?p=1666

605

Gallery / Industrial Night shot with terror moon

« on: 2014-03-12, 14:04:38 »

As it states.

606

Work in Progress/Tests / Re: Häagen-Dazs Wip

« on: 2014-03-11, 18:13:11 »

Here comes the need  for a sss shader.

607

Work in Progress/Tests / Re: Night shot

« on: 2014-03-11, 17:56:26 »

Some to work with:
BEAUTY
Z
NORMAL

Just my 2 pesos...

And my version... XD. A little more close to:
http://www.ncrarefinery.com/Main/PhotoGallery/Photos/RefineryNight.jpg

608

Work in Progress/Tests / Re: Night shot

« on: 2014-03-10, 23:54:00 »

Pretty awesome indeed!... could you share some tips on the post processing?. The force is weak with me in post. XD.

609

Work in Progress/Tests / Re: Night shot

« on: 2014-03-10, 22:06:37 »

A little update adding the moon in post. I'm quite pleased with the results.
Starting to like Corona a lot.

610

Work in Progress/Tests / Re: Night shot

« on: 2014-03-10, 02:48:54 »

All rigth... start from scratch.

The moon ligth isnt blueish as i tough  has a temprature of 4100-4150 a rather yelowish tone. And thanks to this http://en.wikipedia.org/wiki/Purkinje_effect we perceive as blueish. So i put the Corona sun as 4150 Kelvin Temp.

Respect to relative brightness to dayligth, using this info http://en.wikipedia.org/wiki/Daylight i use 1/1000 as Intensity on the sun.

I-m lost respect the size of the moon respect of the size of Corona Sky but as i intend to apply photoshop on the disc i leave as 5 for now.

I never knew that where a setting like bitmap paging in max and by default where active. If you wish to wait for your renders forever leave this on. See this as reference http://jokermartini.com/2013/11/14/render-speed-increase/.Thanks to suggest that.

Using a default Corona material override, in post settings in corona use 4150 as white balance as the predominant ligth source was the moon. Giving me a yelowish tone. But just as stated before our eyes shift that illumination to blue so i try a value of 3150 to return to that blueish color.

For the lamps i put corona sphere 3000 Kelvin  for simulating tungsten ligth. This link explains a little about moonligth photography http://www.cast-lighting.com/search/1/display-document/71

I try an spherical star map as suggested in the forum but it turns out that the stars renders too big and unnatural.
This is the link for that realistic position and brigthness star field http://paulbourke.net/miscellaneous/starfield/

Resume>
IMAGE 4150ML-4150WB   4150 kelvin sun, 4150K White balance in postprocessing tab
IMAGE 4150ML-3150WB   4150 kelvin sun, 3150K White balance in postprocessing tab to mimic blueish tint from human eye
IMAGE 4150ML-3150WB/3000TL   4150 kelvin sun, 3150K White balance in postprocessing tab, corona ligth 3000 K Tungsten ligth , corona ligth sphere
IMAGE STARFIELD just a render whit spherical star map from http://paulbourke.net/miscellaneous/starfield/

Thats it for now...

611

Work in Progress/Tests / Re: Night shot

« on: 2014-03-09, 23:58:23 »

The same using dayligth system from max whit coronsun, no skyligth.
I set the sun time by 23:00 pm and i get this kind of sunset mood.

Guys in the forum told me that i could turn corona sky in to a moon with litle effort... lets see what can i came up to.

612

[Max] Resolved Feature Requests / Re: CoronaMoon

« on: 2014-03-09, 23:56:16 »

Maravilloso.

Thanks for the link.
Ah.... i'ts always been done before... let's put that maps for a good use.

613

[Max] Resolved Feature Requests / CoronaMoon

« on: 2014-03-09, 22:11:32 »

Just an idea...  to CoronaSun.

And environment map that mimics a night sky with stars and moon.
Actually one could select a place on globe and a date and generate some kind of exr texture to put in the environmental slot.
For shure there is plenty of places on the net where one could pick information for that.
Off course a slider to set the amount of stars and moon size. I've seen that maps on cell apps.

It would be a totally awesome add for Corona.

... or just add a greater than 90 degree slider to the corona sun model to mimic nigth sky.

Just my 2 pesos cuates...

614

Work in Progress/Tests / Re: Night shot

« on: 2014-03-09, 21:55:11 »

You were right... deleted the sky dome mesh and put the hdri in the environment slot. Much better, however not quite there yet.

I'm gonna try the sun model from corona. Also replace the mesh emitters  for sphere lights.
It is possible for sun model from corona can mimic night? (If i put an adecuate angle greater than 90 degree?). Could be a good addition.

615

Work in Progress/Tests / Night shot

« on: 2014-03-08, 20:44:05 »

I havent seen any night shots in the gallery so i converted one industrial scene i have using the scripts in the forum from Vray.

Pretty much out of the box settings on corona, one hdri in environmental slot and a couple of mesh emitters on the lamps.
19 hours so far.
The hdri shows as some small brigth dots on the back. Some kind of bug?. I lower the hdri to 0.01 (from 1 as default) to mimic night illumination from sky.

Any suggestions would be very appreciated.