10 M DEM and Derivative Layers Posted!

February 23, 2012

Mike Brouillette, VCGI

VCGI is happy to announce the release of a new 10m statewide DEM and derivative layers from the recently completed (Jan. 2012) statewide 1/3 arc-second (~10m) DEM from the USGS National Elevation Dataset (NED). The NED is a multi-resolution dataset so for areas where LiDAR data exists the vertical accuracy is higher and subsequently the derived contours won’t match the 7.5′ USGS Quad Contours very well. See the Abstract section of ElevationContours_CN20T for more on this issue.

While the layer ElevationContours_CN20T can be custom downloaded, i.e. “clipped and zipped”, the other datasets are statewide in extent and compressed to “zip” files due to their size. These zip files contain both metadata and layer files you can elect to use in ArcGIS.


  • ElevationDEM_DEM10m               (342 Mb) – 10m DEM
  • ElevationContours_CN20T            (990 Mb) – 20′ contours
  • ElevationOther_ASPECT10m         (358 Mb) – Aspect identifies the down slope direction of the maximum rate of change in value from each cell to its neighbors. Values rounded to nearest Integer.
  • ElevationOther_HILSH10m            (299 Mb) – Hillshade from 315 degree azimuth and 45 degree altitude
  • ElevationSlope_SLOPE10m           (135 Mb) – Reclassed “percent rise” slope values rounded to nearest integer.


  • USGS states the NED can be used for hydrologic modeling but VCGI has not conducted any verification. It is highly recommending you review this issue before investing substantial resources in a modeling project.
  • WaterHydro_VHD – These features are based on the earlier black and white Orthophotos (1994-2000), and will not necessarily match up with the 10m DEM or the latest vintage of Orthophotos (2005-2010).
  • VTHYDRODEM – Created in 2004, this VT “hydrologically enforced” DEM (using the local resolution NHD for VT, i.e., the “VHD”) was interpolated from the VT Mapping Program orthophoto rectification X, Y, Z points to support the NHD effort and creation of “WaterHydro_VHDCARTO”, a cartographic version of the NHD with “intermittent” and “perennial” modeled streams. Having created it and working with ElevationDEM_DEM10m I would say the latter is more accurate. However, this raster does have the advantage of being integrated with the VHD.
  • ElevationContours_CN100T and *_CN50T – These are not currently based on the 1/3 arc-second NED and will be replaced sometime in 2012. Until then they will not be coincident with *_CN20T.

The following pre-existing contour data will be superseded by ElevationDEM_DEM10M

  •  ElevationContours_CN20T06A     20 ft contours from Ortho DEM – Addison, Wash, Orange Cnty
  •  ElevationContours_CN20T06B    20 ft contours from Ortho DEM – Rutland & Windsor Cnty
  •  ElevationContours_CN20T07      20 ft contours from Ortho DEM – Chit, Lam, Caledonia Cnty
  •  ElevationContours_CN20T08      20 ft contours from Ortho DEM – GrandIsl, Frank, Orlean Cnty
  •  ElevationContours_CN20T09      20 ft contours from Ortho DEM – Essex Cnty

Please feel free to contact me directly with questions, feedback about the metadata and any content or grammatical errors: Mike Brouillette, mailto:mikeb@vcgi.org


VT GIS Update – February 2012

February 17, 2012

Leslie Pelch, VCGI

Coming Up

Webinars (all free)

Scheduled (click here for details and to register):

  • Free Online Mapping with ArcGIS Online: March 6, 2012, 10:30 AM
  • E911 PMF Map and Website Overview: March 13, 2012, 10:30AM


Ignite Spatial Vermont: Student Showcase

The event will be held in the evening on April 17, 2012 at the Capitol Plaza Hotel in Montpelier, VT; Cash bar and appetizers will be provided.  The “Ignite” format provides speakers the opportunity and the challenge to tell their spatial story in only 5 minutes! The quick pace means that participants can learn about a multitude of projects and then network and follow up on topics that caught their interest. In 2012, we invite students of Vermont’s colleges and universities to submit abstracts to participate in this exciting event along with  professionals from a wide range of private, non-profit, and public organizations that use GIS.

Visit the web page to learn more about this event, and to submit a lightning presentation abstract or register to attend (for free!): http://www.vcgi.org/commres/?page=./events/ignite/default_content.cfm


VT College and University Student Map Contest

VCGI and a coalition of academic institutions in VT are pleased to present the first VT Map Contest (in a number of years, anyway). Any and all digital maps (dynamic or static) can be submitted! The only limitations are that the map must be viewable by the general public via a web link (URL – VCGI can provide a place to post the map if it is a PDF or image file) without the need to pay for special software, and the author(s) of the map need to be current full or part-time students at a VT institution of higher learning. Deadline for submission is April 1! Winner will be announced at April 17 Ignite event (see above).

Visit the map contest web page for more information and instructions on how to submit your map! http://www.vcgi.org/commres/?page=./map_contest/default_content.cfm


Introduction to ArcGIS 10 Training in Randolph, June 11-13

This 3-day training is still being planned, but the location and dates are set! Keep an eye on the front page of VCGI’s web site for details and registration link. The training will be conducted by UNH Extension in partnership with VCGI and the fee will be $350 (nonprofit, school, public enployees) or $495 (private sector).


NEARC Spring Conference – call for papers

The NEARC Spring Conference will take place Tuesday, May 22 at the Smith College Campus Center in Northampton, MA. Submit your “presentation proposal” by March 23!   See the schedule of the day and link to the submission form here: http://www.northeastarc.org/html/springnearc.shtml

There are many different ways that you can participate in this fun and dynamic event: Extended Talk (45-60 Mins.), Panel (45-60 Mins.), Standard Talk (20-30 Mins.),   Workshop (60 Mins.), Lightning Talk (5 Mins.), Video Poster, Poster.

Other Features of the NEARC Spring Conference include Lightning Karaoke, the Pub Social and more!




BNDHASH Updated! – Steve Sharp ( steves@vcgi.org )

BNDHASH has been updated and is available for download here.


Significant Boundary Changes – Summary (2011A)
1) Saint George / Shelburne Town line.  Adjusted to match Survey “Town Line Agreement between Towns of: Shelburne & St. George Chittenden County State of Vermont” conducted by a licensed land surveyor employed by Civil Engineering Associates, Inc. and dated March 9, 2011.  Boundary codified by VT Legislature in 2011 H. 452 (ACT 0015).  Recieved copy of survey boundary in shapefile format from CCRPC.

2) Braintree / Rochester town line.  Adjusted based on latest matching Braintree/Rochester parcel data provided by TRORC.

3) MA / VT boundary.  Adjusted MA / VT boundary based on survey point data provided by MassGIS http://www.mass.gov/mgis/townssurvey.htm which was derived from 68-volume MA “Harbor and Lands Commission Town Boundary Atlas”.

Minor Updates (2011A)
1) Tweaked Norwich/Harford boundary based on the latest parcel data to correct a problem.

2) Updated LEPC boundaries based on new information.

3) Adjusted boundaries for several villages to match 2011 boundary information provided by VTrans from their HMS system.


VTrans County/Town Maps Updated, Sara Moulton, GISP

An updated set of the County-Town Map Series has been posted online and is available from the Mapping Unit Publications web page


The major change is the note in the legend identifying that Minor Collectors are not Federal Aid eligible.  Other changes included small cartographic changes plus the road centerline data that has been updated since the previous map set was produced in September-October 2010.


Links to the Past


Webinars Recorded and Posted (click here to access):

  • Web Mapping Made Easy I – Leslie Pelch, VCGI, February 2, 2012
  • Linking Parcel Maps/Data and Grand List Data – Pete Fellows, Two Rivers Ottauquechee Regional Commission, January 12, 2012


ESRI Seminar Materials re: ArcGIS Online



Municipal and Irene Mapping Conference Presentations Posted

Click here to go to the Event Archive where all conference presentations are posted (as they come in, check back if they one you want isn’t posted yet!)



From Jonathan Frishtick:

  • From GPS TrackLog:”The National Telecommunications and Information Administration (NTIA) wrote the FCC yesterday (PDF) saying they had concluded “that LightSquared’s proposed mobile broadband network will impact GPS services and that there is no practical way to mitigate the potential interference at this time.” Shortly thereafter, the FCC announced that they would “(1) vacate the Conditional Waiver Order, and (2) suspend indefinitely LightSquared’s Ancillary Terrestrial Component authority to an extent consistent with the NTIA letter.” http://gpstracklog.com/2012/02/fcc-kills-lightsquared.html