3D Modelling

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3D Modelling

• Week 3
• Advanced modelling

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Aims of today

• Discuss your presentation
• Advanced modelling

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Last week

• Software
• Modelling concepts
• Polygon
• Spline
• Patch
• Parametric
• 3D parametric modelling
• Primitives
• Transformations
• Aligning
• Cloning
• Modifying primitives
• Boolean

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Plan your model

• Massing model?
• Use a graphic or scan?
• Set up your grid
• Set up a file/folder system

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Sketch or Storyboard
Adventure Gamers Dreamfall from sketch to 3D
model (2005)
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Accuracy

• Imagine a pen
• How would you model it?
• Now look at a real pen
• Details make a big difference
• Practice to be imperfect
• Why?

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References

• Using reference materials will improve the
  quality of your model
• Build a reference library
• The object itself
• Photographs
• Drawings
• Video

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2D

• One method of creating a complex 3D object
• Convert the lines into 3D objects
• Visualise and define cross-sections
• Proper scale

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2D to 3D - Extrusion
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2D to 3D - Lathing

• Create a path
• Choose an axis

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2D to 3D Sweep or Loft

• Create a 2D shape
• Create a path
• Cap or close the ends?

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2D to 3D - Skin

• Create a number of cross-sections
• Skin them

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Activity

• Draw a 2D shape and extrude it
• Create another 2D shape and lath it
• Create a 2D shape, a path and create a loft
• Find out how to do a skin

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File formats for modelling

• Portable or universal file format
• DXF .dxf
• Drawing Interchange Format
• Widely used in CAD (Computer Aided Design)
• OBJ .obj
• Computer animation an visual effects
• Native
• May be converted
• 3ds max .max

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Exporting/importing files

• File conversion
• 3D Studio (3DS)
• Adobe Illustrator (AI)
• ASC Scene Export (ASE)
• AutoCAD (DWG)
• AutoCAD (DXF)
• Shockwave 3D
• FiLMBOX (FBX)
• Initial Graphics Exchange Standard (IGES)
• Lightscape Material (ATR)
• Lightscape Blocks (BLK)
• Lightscape Parameter (DF)
• Lightscape Layers (LAY)
• Lightscape View (VW)
• Lightscape Preparation File (LP)
• Stereolithography (STL)
• VRML97 (WRL)

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Edges

• Real objects rarely have a sharp edge
• Bevel or chamfer
• Radius
• Fillet

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Surface Modelling

• More free form than geometric (parametric)
  modelling.
• A subdivision surface is a surface that has been
  divided into more faces while retaining the
  object's general shape
• Subdivision adds more detail to an object, or to
  smooth it out
• Use modifier stack to collapse a parametric
  model to some form of editable surface.

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Why surface modelling?

• Great flexibility in modelling
• Game engines expect a mesh
• Default model type
• During rendering polygons are smoothed out
• Meshes allow the optimisation of models
• Reduce the number of faces
• Low polygon modelling
• Reduce rendering time
• Key part of successful production

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Mesh objects

• Early versions of Max used triangles
• All faces were coplanar
• Good for the rendering engine
• Over time rendering engines have been modified
• Polygon modelling without subdivision
• More efficient
• Eliminated extra edges
• More control over the polygon object

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Meshes

• Triangles
• Vertex
• Edge
• Face
• Polygons
• Vertex
• Edge
• Border
• Polygon
• Element

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Mesh or poly - which to use?

• History lesson
• Initially Max only supported mesh objects
• Subdividing the mesh into triangular faces
  ensured that all faces were coplanar
• Guaranteed to render well
• Over time rendering engines have been modified to
  handle polygons
• Makes the model more efficient
• Eliminates all the extra edges required to
  triangulate the mesh

Murdock K.L. (2005)
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Tessellation

• Subdivides the faces of the object into two or
  more
• Polygons
• or
• Triangles

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Converting to editable objects

• Use the Quad menu
• Or
• Right click the object in the Modifier Stack

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Editing a polygon model

• Convert an object into a editable polygon
• Removes all parametric controls, including the
  creation parameters
• If a modifier has been applied to an object you
  need to use the Collapse All command first
• Combines the stack operations
• Cannot undo, save a backup file

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Editable Mesh Surface

• Polygon mesh

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Edit face

• Faces provide the renderable surface of an
  object.

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Extrude

• Soft selection
• Extrude
• Bevel

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Activity

• Make a crown
• Create a tube
• Convert to an editable mesh
• Extrude polygons

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Soft selection

• The Soft Selection controls allow you to
  partially select sub-objects in the vicinity of
  an explicit selection
• This causes the explicit selection to behave as
  if surrounded by a "magnetic field"

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Working with vertices

• Select one or more vertices
• Magnetic of soft selection
• Use for transforms of vertices
• The program applies a spline curve deformation to
  unselected vertices surrounding the transformed
  selected sub-object
• A magnet-like effect with a sphere of influence
  around the transformation

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Activity

• Create a sphere
• Convert to an editible polygon
• Push and pull vertices to make a face
• Not easy!

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Edit Edge

• An edge is a line, visible or invisible, forming
  the side of a face and connecting two vertices
• Two faces can share a single edge

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Optimization

• Simplifies a smooth model with a high number of
  faces
• Does not greatly change the models appearance

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Building Organic Forms

• Humans are really hard to do
• Working with Meshes and Vertices
• Skinning
• Working with cross-sections
• Can be provided by a scan
• Magnetic Resonance (MR)
• 3D laser
• Metaballs or Blobby surfaces

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Metaballs or Blobby surfaces

• Build a form from various sized objects
• Blend the surfaces together into a single mass

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Terrains

• Terrain objects can be created from contour line
  data
• Editable splines are selected
• a mesh surface created over the contours

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Low polygon modelling

• What happens to a game if the polycount in a
  model is too high?
• Too slow to play
• May crash the system
• Overlapping meshes or undeleted faces may affect
  the appearance
• Planning of low polygon models is important

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Spec-ing a low polygon model

• File format
• Number and type of polygons
• Use of texture maps
• Particular type?
• Colour depth?
• Specific size?
• Transparency?
• Examine any sample models

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Poly counts

• Total number of polygons that make up a given
  object
• 3D engines have limits
• Number they can move around in a given scene
• Software has a Polygon Counter utility
• You can set a budget fop elected objects
• Unnecessary polygons can be removed
• Use MultiRes
• Polygons can be made to look softer
• Use MeshSmooth

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Level of Detail

• Models are created in two or more levels of
  detail
• Use high polygon model when the object is large
  in the scene
• Swap for the low polygon version when zoomed out
• Used in VRML or X3D

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Billboard

• Define a flat surface which is camera aligned
• Apply a texture
• Renders faster than if a 3D object is used

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Box models and textures

• Simple way to add detail
• Keeps model simple
• Box with a texture added
• More later with materials

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Low poly techniques

• No new skills
• Greater precision
• Decisions on where to invest detail
• Decisions on where to simplify

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Mesh structure

• Several meshes are attached to make a single
  object
• Either
• Weld the meshes together to form one mesh
• Or separate them by a fractional amount
• Do not intersect meshes
• Delete any hidden faces

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Game engines

• Real time 3D engines may use rendering which
  smoothes out your model
• You may need to take special steps to avoid this
• Detaching groups to make them sharp

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Self assessment

• What are the four types of modelling concepts
  used by modelling software?
• What is the most useful for gaming?
• Why is this used for gaming?
• Why does it not work well for
• Rendered views?
• Organic shapes?
• Discuss the four methods of converting 2D shapes
  to 3D
• Give an example of each for constructing everyday
  objects

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References

• Adventure Gamers Dreamfall from sketch to 3D
  model http//www.adventuregamers.com/article/id,47
  7/p,2, accessed 23/09/2005 Giambruno M, (2002) 3D
  Graphics Animation, 2nd Edition, New Riders,
  ISBN 0-7357-1243-3
• Kerlow I. V., (2003) The Art of 3-D Computer
  Animation and Effects , 3rd Edition, John Wiley
  Sons Inc ISBN 0471430366
• Murdock K. L., 3ds max7 Bible, Wiley Publishing
  ISBN 0-7645-7971-1
• Screen shots taken from 3ds max 7 User Reference
  and tutorials