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ArcView 3-D Analyst

ArcView 3-D Analyst. Triangulated Irregular Network (TIN). A Mesh of Triangles. Triangle is the only polygon that is always planar in 3-D. Lines. Surfaces. Points. Tin Triangles in 3-D. (x 3 , y 3 , z 3 ). (x 1 , y 1 , z 1 ). (x 2 , y 2 , z 2 ). z. y. Projection in (x,y) plane. x.

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ArcView 3-D Analyst

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  1. ArcView 3-D Analyst

  2. Triangulated Irregular Network (TIN)

  3. A Mesh of Triangles Triangle is the only polygon that is always planar in 3-D Lines Surfaces Points

  4. Tin Triangles in 3-D (x3, y3, z3) (x1, y1, z1) (x2, y2, z2) z y Projection in (x,y) plane x

  5. Delauney Triangulation Maximize the minimum interior angle of triangles No point lies within the circumcircle of a triangle Yes No

  6. Draw the perpendicular bisectors of each edge of the triangle Circumcircle is centered on their intersection point Radial lines from center have equal length Circumcircle of Triangle

  7. Soft Breaklines Hard Breaklines Mass Points Inputs for Creating a TIN • Hard breaklines define locations of abrupt surface change (e.g. streams, ridges, road kerbs, building footprints, dams) • Soft breaklines are used to ensure that known z values along a linear feature are maintained in the tin.

  8. TIN for Waller Creek

  9. TIN with Surface Features Classroom UT Football Stadium Waller Creek

  10. A Portion of the TIN

  11. Input Data for this Portion Mass Points Soft Breaklines Hard Breaklines

  12. TIN Vertices and Triangles

  13. TIN Surface Model Waller Creek Street and Bridge

  14. 3-D Scene

  15. 3-D Scene with Buildings

  16. Watershed Modeling With TINs Slides from Dr James Nelson Brigham Young University Sponsored by National Highway Institute US Department of Transportation

  17. Work Flow Tin-based Watershed Delineation

  18. 13.0 10.0 9.0 5.0 2.0 Flow On a Triangle

  19. Flow On a TIN

  20. Defining Basins

  21. Computing Basin Data • Area • Slope • Flow Distances • Slopes • Aspect • Stream Lengths • Slopes • Others

  22. Add Outlets • Refine Boundaries • Merge Basins • Split Basins • Delete Outlets • Recompute Data Modifying Basins

  23. Ten Steps Using TINs 1. Background Elevation 2. Smooth Elevations 3. Conceptual Model 4. Redistribute Vertices 5. Create TIN 6. Edit TIN 7. Add Interior Outlets 8. Define Basins 9. Refine TIN 10. Compute Basin Data

  24. 1: Background Elevation • TINs • Digitized • XYZ Data • DEMs

  25. 2: Smooth Elevations • TINs or DEMs

  26. TOPAZ • Contours • Image • Importing • GIS • DXF 3: Conceptual Model

  27. 4: Redistribute Vertices • From Coarse to Fine • From Fine to Coarse • Unequal Distribution

  28. Conceptual Model • Triangulate • Enforce Breaklines • Interpolate Z 5: Create TIN

  29. 6: Edit TIN • Flat Triangles • Pits

  30. 7: Add Sub-basin Outlets

  31. 8: Define Basins

  32. Split Flow • Refine • NULL Triangles 9: Refine TIN

  33. 10: Compute Basin Data • Basins • Area • Slope • Avg. Elevation • Length • Streams • Length • Slope

  34. Ten Steps Using TINs 1. Background Elevation 2. Smooth Elevations 3. Conceptual Model 4. Redistribute Vertices 5. Create TIN 6. Edit TIN 7. Add Interior Outlets 8. Define Basins 9. Refine TIN 10. Compute Basin Data

  35. TIN Strengths • Automated Basin Delineation with Parameter Calculations • “Adaptive” Resolution • you can use most any elevation data source • Urban Areas • where small variations in flow can be significant • It Was in WMS First • reservoir definition, storage capacity curves, time area curves, flood-plain delineation

  36. TIN Weaknesses • Lack of Available Data • With conceptual model approach this is not such a big factor anymore • Extra Steps • Local editing

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