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   The following are notes on painting textures,
   once the 3D model has been UV Unwrapped:

          1. Character Texturing Tips
          2. Major Mapping Types
          3. XNormal


CHARACTER TEXTURING TIPS: Some notes on Character Painting and Shaders:

  1. Highlight Main Features: use darker and moe saturated colors, like more red, on the ball of the nose, the cheeks, lips, and ears.

  2. Think like Stage Makeup: paint shadows on the side of the nose to emphazise the form, darker circles around the eyes/eyeball to help the eyes to pop, color on the chin to make it clear. This image from the film "Paranorman" shows this emphasis (click for larger image):

  3. Consider a painterly approach where brush strokes are visible. This face from the animated short "Meet Buck" appears to have used a square brush (click for larger image):

  4. Use an Ambient Occlusion layer in your textures to emphasize the entire form with self-shadowing. This can be placed in your painting program above your art and set to the "Multiply" blending mode (see notes on free Xnormal program, below).

  5. HAIR: Use opacity maps for hair in games or when full simulated hair is not right for the production, either due to style considerations or budget constraints. Here is a tutorial by Paul Tosca on hair texturing with opacity maps on polygon fins and shells: http://www.paultosca.com/varga_hair.html

  6. EYES: "Its all in the Eyes" By Adam Baroody: http://www.3dluvr.com/rogueldr/tutorials/eye/eyes.html

  7. HUMAN SKIN: Subsurface Scattering tutorial by Philippe Le Miere: http://www.3dtotal.com/index_tutorial_detailed.php?id=824#.URkKlPI-dEM

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DIFFUSE COLOR MAPS are the painted color surface of a model, and should include all the variation caused by wear, tear, and dirt. AMBIENT OCCLUSION self-shadowing can be painted into the map to enhance the form (see XNormal tutorial below). Diffuse color is just the start of the surfacing process.

OPACITY / TRANSPARENCY MAPS are black, white and gray images which create the illusion of enhanced detail by cutting holes in a planar model surface. This can be very effective for a lace curtain, tattered cloth, a terrace on a distant building, or hair and fur. Usuaully, black is cut out and white is visible. Opacity maps can also be used to make semi-transparent dirt or cobwebs or plastics with shades of gray.

BUMP MAPS are grayscale images which create the illusion of enhanced detail on a model surface by faking shadows and specular highlights. Use bump for fine detail: the grout between bricks in a wall, clothing seams and the teeth of a zipper. Bump maps only work in the direction facing the viewer; the silhouette of an object is not affected. A NORMAL MAP is a specalized Bump map that provides a greater sense of depth by using colors to access X, Y, and Z directions, but like regular Bump the result does not affect the silhouette.

SPECULAR MAPS control how light reflects differently on various surfaces. Specular maps are meant to be seen animated, so the light can move over the surface and show changes in brightness, shape, and color.

  • SPECULAR LEVEL MAP: A detailed grayscale image to control the brightness of specular reflection on each part of the object. Often starts as a de-saturated version of the Diffuse map to include all of the dust, dirt and scratches that could affect how light reacts to the surface, and then futher modified. Lighter areas reflect brighter, darker areas reflect less. Black does not reflect.

  • GLOSSINESS MAP: An image of solid gray blocks to define the “tightness” of the specular shapes: how sharp is the edge of each highlight. The areas you want to have a tighter highlight should be lighter gray and the areas you want to have a softer / more spread-out highlight should be darker gray. A wet material would have a very sharp specular. A rough material, especially cloth, has a specular highlight with a softer edge.

  • SPECULAR COLOR MAP: A color image which changes the color of the surface at the highlight. While most materials reflect white or near-white highlights, metals reflect some color. The Specular color is usually not the same as the Diffuse color. Try different colors to bring out interesting results!

Multiple mapping types are used together to create rich and believable surfaces.
If an object has dents and scratches, those areas should be discolored in the Diffuse map, Bumped inward (darker) or outward (lighter), and given different Specular values (less or more bright), all in the exact same location, for the effect to feel complete. A subtle stain can be discolored in the Diffuse and made brighter or darker in the Specular in different overlapping shapes (not in the exact same location) to create more "action" on the surface.

Useful tutorials on specularity work:

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XNORMAL is a free program by Santiago Orgaz to create Normal Maps and Ambient Occlusion textures.

Free Download: http://www.xnormal.net/Downloads.aspx
Note when installing this program the "Xvid" files can be removed.

Here are steps for rendering Ambient Occlusion (a texture of shadows caused by geometry depth and overlap):

[A] From your 3D package (Max, Maya, etc)Max:
Export an FBX of your unwrapped geometry. This can be a character, a single object, or a collection of objects that you want to occlude each other, like the furniture and surfaces in a room, although this will need two FBXs: the entire room with the object, and then just the object itself. Note the FBX can be deleted after completing the XNormal process.

[B] In XNormal:
Note the tab buttons on the right. We will only be using the first three buttons in this tutorial.

    High Def:
  1. Click the "High Def" tab.
  2. Click and drag the FBX file from your folder into the work area in XNormal, and note that this work area updates with the FBX name.
    Low Def:
  1. Click the "Low Def" tab.
  2. Click and drag the FBX file from the windows folder into the work area, and note that the work area updates with the FBX name.
    Baking Options:
  1. Click "Baking Options" and apply these settings:
    • Choose the output file by hitting [...] at the top and choose a JJPG (note the name will automatically add "Ambient Occlusion" when rendered),
    • Set Size = 1024x1024 and Edge Padding = 4.
    • In the list below turn off "Normal" and turn on "Ambient Occlusion." You can click its [...] option box and choose Rays=1024.
  2. Hit the Generate Map button at the bottom and choose "Notify Tile Updates" on the top rolldown to watch its progress!

Note: if you have an object that is actually two maps (multi/sub-object) you will need to export the geometry for each map separately, bring them both into "High Def" and then take turns putting each in "Low Def" and changing the export name. Low Def is always the destination of the projection.

When you want to remove an FBX layer form XNormal, simply select and hit [Delete] on the keyboard.

[C] In Photoshop
Place the Occlusion map TGA in a layer above the color art on your textures, and set it to blending mode "Multiply" to see the shadows enhance and intensify your color art.

Export two models instead of one: the lower poly mesh and the higher poly one. Drop these into the appropriate slots in XNormal. Choose the Normals map option instead of Ambient Occlusion. Give the file a new name and render! For 3ds max Material Editor, the final result goes into the Bump channel using the NormalsBump map type.

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