Under the Surface: Creating Accurate Surfaces in Civil 3D

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Under the Surface Creating Accurate Surfaces in
Civil 3D
Scott Wagner, P.E. Business Development Manager
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Introduction

• Who am I?
• Why this is important to me?
• Poll
• Handouts/Questions
• Objectives

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Objectives

• Understand how to make a surface in Civil 3D
• Understand the theory behind making a surface in
  Civil 3D
• Understand how to perform surface edits
• Understand how to apply surface masks
• Understand an overall strategy on how to create
  an accurate surface.

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Agenda

• Differences between Land Desktop Surfaces and
  Civil 3D Surfaces
• Create a Surface from Point Group
• Types of Surfaces
• Create a Surface from Contours, Point Files DEM
• Surface Evaluation Process

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Under the Surface Land Desktop vs. Civil 3D

• Ill Race You.And Ill Win!

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Under the Surface Land Desktop vs. Civil 3D

• Land Desktop 2007 Demonstration

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Under the Surface Create a Surface from Point
Groups

• Creating and Viewing Surfaces in Civil 3D

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Under the Surface Create a Surface from Point
Groups

• Civil 3D 2007 Demonstration

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Under the Surface Types of Surfaces

• Tin Surface, Grid Surface and Volume Surfaces

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TIN SurfaceThe Most Common Surface Type

• TIN surfaces provide an accurate surface model
  that is widely used.
• TIN Surface-
• Triangular Irregular Network. A TIN surface is
  the most common method of interpolating elevation
  data. The points are connected into triangles
  that are used to interpolate for contours, and to
  generate profiles and cross-sections. The lines
  that make up the surface triangulation are called
  TIN lines. (Civil 3D Help)

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Grid SurfaceThe Other Method

• Grid surfaces provide an accurate surface model
  that is largely used with DEM files.
• Grid Surface-
• A type of surface created from a DEM or SDTS
  file, or imported from a LandXML file. A grid
  surface consists of a sampled array of elevations
  for a number of ground positions at regularly
  spaced intervals. (Civil 3D Help)
• It is a grid spaced surface in which each
  regularly spaced cell is assigned a single
  elevation. (Autodesk Education Curriculum for
  Civil 3D 2006)

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Volume SurfaceThe Surface needed to do Volume
Calculations

• Volume Surfaces can either be TIN or Grid.
• TIN Volume Surface-
• A differential surface created from a composite
  of points based on base and comparison surface.
  (Civil 3D Help)
• Grid Volume Surface-
• A differential grid surface based on
  user-specified base and comparison surfaces. The
  grid method of volume calculation measures the
  difference in elevation between two surfaces at
  each intersection in a user-defined grid.
• (Civil 3D Help)

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Under the Surface Create a Surface from
Contours, Point Files, and DEM Files

• Time to go Deeper

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Under the Surface Create a Surface from
Contours

• Civil 3D 2007 Demonstration

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Under the Surface Create a Surface from a
Point File

• Civil 3D 2007 Demonstration

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Under the Surface Create a Surface from a
DEM File

• Civil 3D 2007 Demonstration

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Under the Surface Surface Evaluation Process

• A good process yields good results.

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Surface Evaluation Process

• Create the Surface
• With TIN lines on, View the Surface in 3D to look
  for Spikes
• Use Contours, Flow Arrows and Gradients to Verify
  Slopes
• Look at Boundary Conditions Add boundaries
  where Needed
• Look for Areas where Breaklines can be Added

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Surface Evaluation Process (cont.)

• Look for Flat Areas, or where Triangles edges
  need to be Swapped
• Apply Masks for Better Performance
• Peer Review
• Export to Land XML for Archive of Finished, Ready
  to use Surface

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Conclusion

• Differences between Land Desktop Surfaces and
  Civil 3D Surfaces
• Create a Surface from Point Group
• Types of Surfaces
• Create a Surface from Contours, Point Files DEM
• Surface Evaluation Process

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Contact InformationScott Wagner, P.E.

• E-mail Address
• scott.wagner_at_ideateinc.com
• Ideate Website Address
• www.ideateinc.com
• Additional Civil 3D Webcasts
• www.ideateinc.com/ideas/webcasts.html

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