Thursday, September 5, 2013

Scott Robertson: Rendering Form with Value

http://www.youtube.com/watch?v=OZlpcrpA5u0

Notes:

  • drop in a gradient background (dark grey on top, medium grey on bottom) to start.
    • gradient value opposite of light direction
  • Brain interprets "form" change through "value" change, not color change.
  • If you have a nice line drawing, you can put it on a top layer and set it to "Multiply" and leave it across the top.
  • Whenever you want to introduce a form change, introduce a value change.
  • Use simple top lighting.
  • Opposite value gradient to main light will ensure the silhouette is always visible.
  • Put object on a layer on it's own and check 'preserve transparency' for masking out the background.
  • Quick and dirty:
    • Use Burn and Dodge tools after setting a medium grey fill on object.
    • Dodge on any surfaces where light will hit.
      • Perpendicular to the light will be the brightest.
      • Tangent to light you get "Core Shadow", aka "Terminator"
  • Better way:
    • Make a new layer on top.
    • Click division line between base and top layer while holding "Alt", and you get a clipping path layer.
    • Set to "Multiply" so as to not lose any of the line work.
  • Look to the outside of your silhouette, and if it's an undercut, wrap the shadows around to the front surface.
  • Again, Tangent to your light source is your "Core Shadow"
  • Fill in the "Lights", Fill in the "Darks", then come back and paint in-between the values.
  • Since it's on another layer, you can tweak layer opacity to your liking.
  • Create "Cleanup" layer on top and add refinement and details.
  • Duplicate canopy section and put it on Multiply.
  • Paint in the small details inside the canopy.
    • paint in driver to show scale.
    • paint on specular.
      • soft overall
      • sharp point highlight
Refinement:
  • Take value below from background, and start painting in the bounce light on to the vehicle.
  • It's okay to airbrush over the top of line art.
  • Make sure bounce light doesn't overpower main light.
  • Any forms in the shadow side can be shown using the bounce light.
  • Begin switching from line work to "Surface"
    • To show nice lines, you need nice Surfaces.
    • Two surfaces form an Edge.
  • Put "Radius" on the flat panel edges, as well as 'hard' edges.
  • Work quickly without zooming in, "Just to make things go bump."
  • Form Change = Value Change
  • Side profile drawings are a good practice for rendering because you have to work your values.
  • Also good to work in grayscale because you can concentrate on form.
  • Tutorial currently uses a simple airbrush, but you can use a more textured brush if needed.
    • Could use a flattened elliptical brush for more of a 'painterly' look.
  • Once you get your base forms working, everything looks 3D, you can go in and start "Sculpting" the form.
  • A technique from traditional media, clean up your silhouette with colors from your background. 
That's basically it, other than adding in some color and texture on top.  More to do:
  • Noodle time!:
    • keep refining the:
      • forms
      • volumes
      • cut lines
      • radii
      • fillets
      • planes
      • adding graphics
  • Tip for graphics:
    • Marquee areas to be decals
    • Duplicate layer with marquee info
    • Darken
    • Go back and erase to clean up
  • Can also continue adding details, like mechanical bits, etc.
  • Other render tips:
    • Cool to Warm (outdoor rendering)
    • "Color Dodge" mode gives very metallic surfaces
      • have to go into layer settings and disable:
        • Blend Clipped Layers as Group
        • Transparency Shape Layers
    • CTRL + SHIFT + V: Paste back into place.
    • Incorporate value change into reflections.


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