Aaron,
Whether
the zero elevation contour of the 2 foot contour interval,
State lidar derived contours is represented/shown depends if
the lidar data was originally flown at mean tide or lower.
If the area of interest was flown at a higher tide level
than just below about mid-tide then there will unlikely be
any lidar data to derive the zero contour with. Also note a
zero elevation in the lidar data which is on the NAVD88
vertical datum is unlikely to be mean sea-level as it might
be if the NGVD29 vertical datum is used. The State lidar
data is collected using the NAVD88 vertical datum which is
not a mean sea-level datum. NGVD29 was a mean sea-level
datum.
Jon
Giles
Sebago
Technics, Inc.
207-200-2128
I
was wondering if anyone could tell me how sea-level is
zeroed in the 2' contour layers on the Maine GIS site?
Is it from low tide, high tide, or mean tide level?
Thanks in advance, and I apologize in advance if this
answer is obvious. I didn't see it in the metadata.
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