Town of Honoka‘a

Notes on using VTBuilder to create a 3D model of the small town of Honoka‘a.

Small Elevation Area - Honoka'a3

• extracted directly from 10m DEM, NAD83 at (238600.0, 2219400.0), ( 6000.0, 6000.0)
• at a 2k grid, this is 2.93m spacing (honoka'a3_2k.bt)
• the roads are imported from DLG, and adjusted to align with the NAD83 elevation (honoka`a3.rmf)
• roads are used to deform elevation with 2m margin and fade-off zones, resulting in (honoka'a3_flat_2k.bt)
• attempted to georeference an aerial (#1, below) resulting in:
  • coverage of area (241245.0, 2220960.4), ( 1601.6, 1474.9)
  • at 1639 x 1514 pixels, that's spacing of 0.97718, 0.97417; made corresponding world file

Original Extraction

• starting with big island elevation and vector data
• loaded the USGS 10m DEM, extracted an area at:
  • (239176.4, 2218879.3), ( 6196.2, 6447.7)
  • grid size 1025
• by loading the hydro DLG and comparing the shoreline, there is a big visible offset between the DLG and DEM data
• measured the offset with the Distance tool:
  • 430, -380 meters
• used "Layer - Offset Coordinates" to move the road and water layers to line up with the DEM

snapshot of elevation, road and water data in VTBuilder

• loaded the USGS DRG into BExtractor and extracted the building locations

DRG and extracted buildings in BExtractor

• examined some aerial photos of the area

aerial 1, from a poor photo of a wall print

aerial 2, flatbed scan of a print from Air Survey Hawai`i

• having some trouble aligning the buildings to the other data, currently examining

Resources

• Melvin Ah Ching's Honoka‘a Online & Photos Website