Table of Contents
PPT Slide
Just How Accurate are the 1 foot Ortho Photos?
GPS Topographic Survey Overlaid Onto 1’ Image
Zooming in a bit…….
And zooming right down to the survey monument!!
Another Dose of Accuracy…Street Lights
Looking a bit closer for the light
Follow the shadow and pole to where they meet
Even though we can’t quite see them on 1’ photos...
So we digitized their approximate locations
What exactly are…?
DEM (Digital Elevation Model)
DTM (Digital Terrain Model)
TIN (Triangulated Irregular Network)
Note TIN along Breaklines on this Roadway
See!! No Beaklines for this area of Roadway
Shaded TIN, or Shaded Surface Model
This Proves Columbus Wrong !!
Not. The adjoining dataset MUST be processed simultaneously
Lastly, caution is urged when dealing with bridge polygons
Remove Bridge Polygons for proper channel topography
Removing Polygons and “Draping” an orthophoto over the Shaded Surface Model allows for simulation of a real bridge
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