Page: Dorian Iten - 12 Things Many Artists Never See

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Understanding light is fundamental

Hello thery!

Recently I stumbled over the page from Dorian Itens page 12 Things Many Artists Never See

https://www.dorian-iten.com/see-more

Oh my dear, that page captured my brain and I'm revisting and working on that for 2 weeks. He created a very tense and amazing summary on how to create realism with light and shadow by 12 modeling factors with very clear videos. These are so packed with important aspects that I watched them at least 4 times each.

I'd suggest you to check the page and the videos on your own - cause I can't explain it nearly as good. But I try to bulletize my understanding in the hope that it settles in my memory that way.

To avoid copyright issues and to train the concepts, I tried to recreate his images with Gimp. So please be gracious - it’s my first time to try digital painting and there is lots of room to improve.

Dorian introduces 12 Modeling Factors divided in 4 basic ones and 8 advanced:

Pink sphere on blue background with 12 Factors named

Basic Modeling Factors

4 Basic modeling factors - They are Separating Light and shadow:

  • Makes objects in paintings appear 3D
  • Sample without Basic factors = circle:
Pink circle on Blue background

Formlight

  • Every part of an object that a light source “sees”
  • When positioning your viewpoint from the source of the light every part of the object is bright

Formshadow

  • Opposite of formlight = everything the light doesn’t see

Terminator

  • Separates formlight and form Shadow

Cast Shadow

  • Projected shadow from the object
  • Same shape as Terminator line
  • These properties depend only on the position of light and object. The viewpoint is independent ( that's a different I highlights ). Turning the viewpoint (NOT the object )= same light and dark areas

  • Sample with the basic factors appears as sphere:

Pink circle with Forlight and shadow and cast shadow

8 Advanced modeling factors: Create Realism

Reflected Light

Circle with reflected light
  • Also called Bounce / indirect light
  • Light reflects from surface to another ( e.g. ground to object )
  • It bounces multiple times but will loose intensity every bounce
  • Usually after 2nd bounce it’s not relevant anymore
    • e.g. from ground to object, from object to cast shadow
    • Bounce from ground to object and then from object to shadow again
  • Distance matters:
    • The closer the reflecting surface is to the object, the stronger the reflected light on the object
    • E.g. a cylinder on a plane has less reflected light on top
    • object with least reflected light

  • Color/Value matters:

    • The brighter the surface, the stronger it reflects ( white vs black )
    • The color of the reflected surface is transported to the object
    • .g. yellow ground is highly visible on object, a brown one less
  • Angle Matters:
    • The angle between surface and object impacts strengths of reflection
      • Parallel planes have strong reflections
      • A curved ball has lesser reflections on the curve aways from the surface
  • Don’t think about reflections as individual rays! When lights hits the Surface it diffuses with every point it hits / reflects!
  • Reflected light is always in the shadow
    • It can only rarely  be in light cause it is  weaker version of the light

    Core shadow

    Circle with added half tones
    • That’s the part of the object with least reflected light
    • Part of the formshadow
    • No reflected light, no Core shadow ( all formshadow is equally dark then )

    Half Tones

    Circle with emphasized core shadow
    • Changes in tonal values within form light ( doesn’t apply to shadow! )
    • The farer away a part of an object is to the light the less light it receives
      • That’s why a sphere gets darker at the rounder areas
      • That’s where panel lighting of planes coome from

Highlight

Circle with added highlight
  • More accurate: “Specular reflection” of the lightsource ( not brightest half tone )
  • More shiny or reflective surfaces have sharper highlights
  • In comparison to Half tone, it moves based on the viewer's eye position
  • Lightest value in shading

Center Light

  • Part of the Half tone - Name for the lightest halftone
  • Area of object that points most directly to light source
  • Might not be present on matt surfaces

Ambient Light

  • Not the direct light from sun and lamp
  • But the light reflected from overall environment 
  • That’s why shadows never are totally black
  • Direct light + Environment generates the ambient light
  • Ambient light softens and lightens shadows
    • More ambient light, shadow edges get softer and shadows brighter
    • No impact on form lights or half tones
  • Defines the general brightness of the scene
  • Difference to reflected light
    • Ambient light is not based on a light source, it’s everywhere
    • Ambient light Doesn’t require surfaces within direct light close to each other
    • Ambient light can be colored based on reflections -> winter = snow blue, while sunlight may be yellow

Ambient Occlusion

Circle with ambient occlusion
  • Part of the object blocked from ambient light
  • Usually contact surfaces
  • The closer 2 surfaces are, the darker and sharper the occlusion shadow gets

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