About materials ...

  • 2 Replies
  • 181 Views

0 Members and 1 Guest are viewing this topic.

Offline Voulxe

  • *
  • Fractal Fanatic
  • ***
  • Posts: 33
« on: May 04, 2020, 06:32:03 PM »
While digging again into Mandelbulber, I have a few remarks concerning a few topics.
This one is about materials.

Colors
I often dismiss an image, as I am not satisfied with the balance of lighting and colors. A dark and sinister atmosphere, but I cannot get the colors bright enough. A well lit scene with volumetric light, but pure black is a washed out grey.
I know, the output of an image is limited to 8/16/32 bit color range ... but ...
... it would be great to exagerate the input of the color values, having the possibility to use numbers outside the scale of 0-255 ... as this scale should be only the limitations of the (8bit-RGB) output, not of the calculation.
I am thinking of a two-handed slider which can define the simulated color range ... i.e. from -200 to 512 (from a max. of -16k to +16k).
Such a slider could enhance the use of image textures, too ... Instead of the Texture intensity using such a slider.

Metal or Dielectric
Just a checkbox whether the reflections are tinted in the object's color or not. Maybe for the artist among us ... a slider to change the amount and the tint of the reflections' color.

Roughness
In my opinion, the Roughness Option should be placed much more further to the top of the list and should be highlighted :) Because ...
  • Fresnel:
    Every object in the world shows the Fresnel effect, the visible amount is defined by the object's roughness
  • Specularity:
    The specularity of an object's surface is defined by the absence/presence of roughness

Specularity:
In my opinion a nice and fast tool to simulate some metalic/plastic/wet surface-effects. Concerning the above mentioned thoughts, only one set of options is necessary.

Thanks for the time reading this ...
Voulxe

Linkback: https://fractalforums.org/mandelbulber/14/about-materials/3465/

Offline buddhi

  • *
  • Fractal Feline
  • **
  • Posts: 157
    • Mandelbulber GitHub repository
« Reply #1 on: May 11, 2020, 05:56:29 PM »
About colors:
- color is a function of surface color and light. If you define perfect black and use specular highlights it won't be black. If you define perfect white and light source is too dark it won't be white.
- I would not implement out-of-range colors because it would cause a lot of problems with calculation of shaders

About Metal or Dielectric
You can define the same color gradient of reflection as object color to simulate metalic surfaces

About roughness
Surface roughness can be simulated in many ways. One of them are specular reflections which are really fast for calculation. Much more accurate way is too simulate random changes of surface normal vector (which does roughness option), but it needs Monte Carlo algorithm for good results. User can chose if he want to use fast or accurate way.
Frestel's equations are related to reflections/refraction and they defines amount of refleced light according to angle of incidence and index of refraction.

About specularity
I think the best would be to have choice of different functions for light decay.

Offline Voulxe

  • *
  • Fractal Fanatic
  • ***
  • Posts: 33
« Reply #2 on: May 12, 2020, 05:59:53 PM »
Quote
- I would not implement out-of-range colors because it would cause a lot of problems with calculation of shaders
I assume ... as the output of the image can be 16 and 32bit ... that the calculations are a bit more in 'depth' than the 8bit RBG that the user is limited for input.
For the image adjustments we have the possibility to change contrast saturation, brightness and ... gamma :)
And gamma is just one of three variables of leveling the color range.
The other two are the black- and the whitepoint. If I enter a user value ... an offset ... of for example -5k for blackpoint and +100 for whitepoint, why would that cause problems within the calculation?
Isn't it just a post-processing?
The nice thing about this feature is, I do not have to export an EXR, load it into my HDR-Converter (as Gimp sxs), test a few settings ... then changing accordingly in MB, testrender, export, tweak ... when most of the color range could be visualized within Mandelbulber itself.
Quote
About Metal or Dielectric
You can define the same color gradient of reflection as object color to simulate metalic surfaces
True, but this excludes shading based on image textures.
Quote
About specularity
I think the best would be to have choice of different functions for light decay.
I double this :)

Thanks for taking your time,
Volker


xx
Mandelbulber 2.20-dev Materials Have Changed

Started by Tas_mania on Mandelbulber

0 Replies
251 Views
Last post November 17, 2019, 06:18:05 AM
by Tas_mania