Hello Aaron, NO - In answer to your question: /sea-level in 2' contour shapefiles?/ Todd Metzler and Jon Giles are correct, the 2006 lidar data for Cumberland and York Counties; for example, are based on the terrestrial datum NAVD88, from which the Contours_2ft shapefiles were derived. Terrestrial datums should not be confused with tidal datums. Their relationship to one another vary and are location dependent. However, if you are interested in knowing (within about 13cm +/-) the relationship between a given terrestrial datum, like NAVD88, and a given tidal datum, like MLLW, at any one location along the Maine coast, for example, there is a fantastic resource available at: https://vdatum.noaa.gov/ And should the question come up, the datums for the 2006 York and Cumberland lidar are more fully: NAVD88 (Geoid03), and the reference frame was NAD83(CORS96) Epoch 2002.00 You may also find these two related resources of interest: http://www.maine.gov/dacf/mgs/hazards/hat/index.shtml http://www.maine.gov/dep/land/slz/predictions.pdf ------------------------------------------------------------------------ /Below an excerpt from // //Topographic Data //Acquisition////Summary Report// //Contract No. EME-2003-CO-0340, //Task Order T017/ -- <http://aerial.panocea.us/> Mr. V. Kelly Bellis, ME PLS 2099 :: WQTS485 17 Union Street :: Ellsworth, ME 04605 http://aerial.panocea.us :: 1+ (207) 667-6912 ------------------------------------------------------------------------ On 9/29/2017 4:26 PM, Jon Giles wrote: > > 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 > > *From:*Maine GeoNews [mailto:[log in to unmask]] *On Behalf > Of *Aaron Gilbreath > *Sent:* Friday, September 29, 2017 3:55 PM > *To:* [log in to unmask] > *Subject:* sea-level in 2' contour shapefiles? > > Hello Everyone, > > 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. > > Thanks, > > Aaron > > Aaron Gilbreath > > 148 East Main St > > Yarmouth, ME 04096 > > (207) 841-4805 > > ----------------------------------------------------------------------- > This list Maine GeoNews (GEOLIBRARY-L) is an unmoderated discussion > list for all Maine GIS Users. If you no longer wish to receive e-mail > from this list, you can remove your name and email address yourself at > the this web address: > > http://lists.maine.edu/cgi/wa?SUBED1=geolibrary-l&A=1 > > Or,you may also request that your name be removed by sending email to: > > [log in to unmask] > <mailto:[log in to unmask]> > > ----------------------------------------------------------------------- > This list Maine GeoNews (GEOLIBRARY-L) is an unmoderated discussion > list for all Maine GIS Users. If you no longer wish to receive e-mail > from this list, you can remove your name and email address yourself at > the this web address: > > http://lists.maine.edu/cgi/wa?SUBED1=geolibrary-l&A=1 > > Or,you may also request that your name be removed by sending email to: > > [log in to unmask] > <mailto:[log in to unmask]> > ----------------------------------------------------------------------- This list Maine GeoNews (GEOLIBRARY-L) is an unmoderated discussion list for all Maine GIS Users. If you no longer wish to receive e-mail from this list, you can remove your name and email address yourself at the this web address: http://lists.maine.edu/cgi/wa?SUBED1=geolibrary-l&A=1 Or,you may also request that your name be removed by sending email to: [log in to unmask]