3D Analyst Geoprocessing by frl11674

VIEWS: 86 PAGES: 44

									3D Analyst Geoprocessing



     Clayton Crawford




                           2009 Technical Workshop
3D Geoprocessing Tools




  • Surface Tools
     – Creation
     – Editing
     – Analysis
  • Data Conversion Tools
     – Between surface models
     – From surface models to features




                                         2009 Technical Workshop
2009 Technical Workshop
Surface Creation



 • Raster
    – Import (core toolset)
    – Interpolation
 • TIN
    – Triangulation
 • Terrain Dataset
    – TIN based




                              2009 Technical Workshop
Raster Interpolation



  • Variety of interpolants
    – TopoToRaster, Natural Neighbors, IDW, Spline, Kriging, Trend,
      TIN/Terrain to Raster (Conversion toolset)
  • Select one to use based on:
    – Application requirements
    – Characteristics of available data
    – Ability of interpolant to handle above




                                                                2009 Technical Workshop
Topo To Raster



 • Strengths
    – Handles contour data on input
    – Hydrologically sound output
 • Supported input data types
    – Contours with height attribute
    – 2D points with attribute
    – 2D polylines (rivers)




                                       2009 Technical Workshop
Spline



 • Strengths
    – Smooth
    – Infers trends
 • Supported input data types
    – Points (2D with attribute, 3D)
    – Barriers




                                       2009 Technical Workshop
Inverse Distance Weighted (IDW)



 • Strengths
    – Fast
    – Interpolated z range within range of data
 • Supported input data types
    – Points (2D with attribute, 3D)
    – Barriers




                                                  2009 Technical Workshop
Natural Neighbors



 • Strengths
    – Conservatively smooth
    – Interpolated z range within range of data
    – Smart selection of samples
 • Supported input data types
    – Points (2D with attribute, 3D)
    – Note: also supported by TIN to Raster tool




                                                   2009 Technical Workshop
Kriging



 • Strengths
    – Probabilistic
    – Well behaved with sparse data
    – Options to tailor results based on input data characteristics
    – Statistical assessment of estimates
 • Supported input data types
    – Points (2D with attribute, 3D)




                                                                      2009 Technical Workshop
TIN/Terrain Dataset



  • Strengths
    – Inputs incorporated directly into model
    – Precise, honors input samples exactly
    – Adapts to variability of terrain
  • Supported input data types
    – Points, lines, and polygons (2D with attribute, 3D)
    – 3D breaklines




                                                            2009 Technical Workshop
TIN/Terrain and Surface Feature Types



 • Mass, break, clip, erase, replace
 • Hard/soft edge enforcement




                                        2009 Technical Workshop
Mass Points




              2009 Technical Workshop
Replace Polygons




                   2009 Technical Workshop
Erase Polygons




                 2009 Technical Workshop
Clip Polygons




Tip: Don’t have a clip polygon? Try DelineateTINDataArea
                                                           2009 Technical Workshop
Conversion Between TINs/Terrains and Rasters



 • Raster to TIN
    – Z tolerance
    – OK to use as ‘smart’ generalization for visualization or when ancillary
      data is available to improve surface
 • TIN To Raster / Terrain To Raster
    – Linear and natural neighbors interpolation options
    – Benefit over Natural Neighbors tool offered in Raster Interpolation
      toolbox is support of constraints like breaklines and clip polygons
 • TIN to terrain dataset
    – Use the tools available to convert TINs to features
      • TIN Node, TIN Line, TIN Domain
    – Build terrain from resulting features




                                                                   2009 Technical Workshop
Radial Search




      Even distribution   Variable distribution


                                           2009 Technical Workshop
Triangle Search




                  2009 Technical Workshop
Natural Neighbors Search




                           2009 Technical Workshop
Profile Comparison Between Interpolants


          1400
          1200
          1000
           800
           600
           400
           200
             0
          -200
          -400
          -600

                  TIN Linear       TopoRaster             Spline
                    Data samples omitted in these areas




                                                                   2009 Technical Workshop
TIN/Terrain to Raster with
Natural Neighbors


                                         ‘hard’ edge




       Linear                 Natural       Natural
                             Neighbors    Neighbors
                                         (break edge)


                                               2009 Technical Workshop
Breakline Enforcement




                        2009 Technical Workshop
Demo




       2009 Technical Workshop
Surface Analysis



 • Derivatives
    – Slope, Aspect, Hillshade
 • Feature Interpolation
    – InterpolateShape, InterpolatePolyToPatch, SurfaceLength,
      SurfaceSpot, Contour
 • Visibility
    – Viewshed, Line of Sight
 • Volume
    – SurfaceVolume, CutFill
    – TINDifference, TINPolygonVolume
    – ExtrudeBetween




                                                                 2009 Technical Workshop
Slope: steepness




Aspect: direction of steepest slope




Hillshade: steepness and direction
relative to light source


                           2009 Technical Workshop
Derivative Calculation



  • Raster based
    – Local functions, 3x3 roving windows
    – Plane fitted to this ‘neighborhood’
  • TIN based
    – Each triangle defines a plane unambiguously




                                                    2009 Technical Workshop
3x3 Roving Windows




       Note: hillshade will not estimate values for boundary cells

                                                                2009 Technical Workshop
Interpolation



  • Feature interpolation
    – Raster
       • Bilinear
       • Sample distance
    – TIN
       • Linear
       • ‘Natural’ densification
  • Contouring
    – Raster and TIN based methods
       • Linear threading through triangles




                                              2009 Technical Workshop
Cell vs. Surface Data Area



  Raster image
   boundary                                                       Surface
                                                                  domain




                 Interpolation zone is ½ cell in from image boundary
                                                                   2009 Technical Workshop
Raster Profile Sampling




                          2009 Technical Workshop
TIN Profile Sampling




                       2009 Technical Workshop
Visibility



  • Line Of Sight (LOS)
     – Inputs are 3D lines
     – Only 1st and last vertices used as observer and target points
     – Raster and TIN implementations
  • Viewshed
     – Frequency and Observers options/tools
     – Raster algorithm
  • Earth curvature




                                                                       2009 Technical Workshop
Line of Sight




                2009 Technical Workshop
Line of Sight

      Elevation




                                            Distance
        observer                                                          target
                  When offset, the target can be visible even though the profile
                  on the surface at that position is not.



                                                                            2009 Technical Workshop
Line of Sight




                          obstruction




        observer                                              target
       When a target isn’t visible, its obstruction point always
       occurs along a visible portion of the profile.


                                                                   2009 Technical Workshop
Curvature and Refraction



 • Adjustment made to consider effects of earth curvature and
   atmospheric refraction on result
    – Curvature reduces visibility over distance
    – Refraction increases visibility
 • More significant impact over longer distances
 • Curvature, in effect, decreases elevation 7.85 meters per 10km
   distance.
 • Use of default refraction brings that back to 6.83 meters




                                                           2009 Technical Workshop
Volumetrics




• CutFill
   – Raster/cell based


• SurfaceVolume
   – Both raster and TIN


• TIN specific
   – TINPolygonVolume
   – TINDifference
   – ExtrudeBetween




                           2009 Technical Workshop
Volume Below Plane




                     2009 Technical Workshop
Volume Below Plane




                     2009 Technical Workshop
Analysis Tools and Terrain Datasets



 • Most surface analysis tools do not yet support terrain datasets
   directly
    – Exceptions: interactive tools on 3D Toolbar
      InterpolateShape and LineOfSight GP tools (9.3)
 • Use TerrainToRaster and TerrainToTIN to extract rasters and TINs
   by area of interest and level of detail
 • Increased support will come in later releases




                                                            2009 Technical Workshop
Demo




       2009 Technical Workshop
Enhancements coming in 9.4



 •   Analysis with 3D vector features
 •   More analysis directly on terrain datasets
 •   Import TINs from LandXML
 •   Skyline




                                                  2009 Technical Workshop
                Questions?




Please fill out and turn in the evaluation form




                                                  2009 Technical Workshop

								
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