Hawai‘i Island Elevation Data

See Hawaii Statewide Elevation Data first; this page describes the Hawaii island data specifically.

• the USGS provides both 7.5-minute and 1° DEMs
• Summary:

  • Data Type	Map Projection	Datum	Vertical Units
    1-degree DEM	Geographic (arc-seconds)	Old Hawaiian	meters
    30-meter DEM	UTM (meters)	Old Hawaiian	meters (some are in feet)
    10-meter DEM	UTM (meters)	NAD83	feet

• 1° DEMs
  • number of files for the whole island: 5
  • free from the USGS web site
  • at 1200x1200 data points per degree, it's 1506x1630 data points
  • ~86m/point (3 arc-seconds at this latitude)
  • using 64x64 point patches, produces a 25x25 grid = 625 LOD patches
  • poor quality: major gridding artifacts, entire island is offset by up to 1 km east, etc.
• 7.5-minute 30-meter DEMs
  • number of files for the whole island: 82
  • cost around $600 from the USGS ESIC on CDROM (what i paid in 1997)
    • now much cheaper, the USGS had a major price drop
  • at 30m per point, about 4300x5000 points = 20 million vertices = 40 million tris
  • much better accuracy than the 1° DEMs
  • 99.01.15: extracted at UTM origin and size (176793, 2091648), (134137, 152721)
    • extents LTRB (176793, 2244369, 310930, 2091648)
    • subsampled to 1k*1k and 2k*2k
  • 99.09.16: extracted a 4k*4k subsample at the same location
• 7.5-minute 10-meter DEM
  • available for the whole island - both from the usual USGS Sources and from UW 10m Data
  • 13000x15000 points = 195 million vertices = 390 million triangles
  • ordered and received - quality is incredibly good
  • quality comparison:

    30 meter

    10 meter

  • 00.01.12: extracted an 8k*8k sampling from the 10m DEMs - that's 16.2m resolution!
  • 04.05.08: went back to 10m DEMs to extract a fresh set of BTs at WGS84
    • Had to shift the extents to match the imagery
    • New origin and size: (177093, 2091478), (134137, 152721)
• NASA SRTM
  • article: Improving Oahu’s image - "NASA says detail in the shuttle radar images will be 30 times greater than that in existing world maps."
  • SRTM has a lot of problems with steep slopes, which are extremely common in Hawai‘i. It can't compete with the existing 10m DEM already available

Undersea

• In addition to the bathymetry data for the whole island chain, there is some Big Island-specific data
• SOEST page Shoreline Imagery for Hawaii
  • includes a Shockwave interface to SHOALS LIDAR bathymetry for certain regions of coastline
  • it's easier to access the Hawaii Shoals folder on their FTP site
• SeaBeam
  • "Two-Dimensional Digital Surfaced Grid of High Resolution Bathymetry (including SeaBeam™ multibeam) and Topography around the Island of Hawai‘i"
  • they collected, reformatted, edited, filtered, and gridded the publicly available data into a DEM!
  • can be licensed
    • contact is Jonathan Roberts at the UH Office of Technology Transfer & Economic Development (OTTED), (808) 539-3828, robertsj@hawaii.edu
  • actually, the "DEM" is in the netCDF format
  • ordered the data in Nov. 1999, received file "BigIsle-I92m-T35-Fm.75D1.grd"
    • file size: 28 MB
    • resolution: 3 arc-second (same as 1° DEM, ~90m)
    • dimensions: 3001 * 2401
    • VTBuilder snapshot to right
    • longitude range = -156° 35', -154° 5'
      latitude range = 18° 30', 20° 30'
  • the above-sea data is simply copied from the USGS 1° DEM data
• USGS Pacific Sea-Floor Mapping
  • has some attractive images of Hilo Bay, but no source data or data descriptions?
• Hawai`i Mapping Research Group
  • has several towed submersibles for seafloor mapping, site has no data