Henderson County - Contour 5 foot

20210927 14575400 FALSE 20090623 11181600 20090623 11181600 1.0 ESRI ArcCatalog 9.2.4.1420 en Based off the USGS DEM 90 meter cells. Henderson County shapefile for 5 foot contours. To view the 5 foot contours correctly you will need to include the 10 and 20 foot contours. Elevation for this county ranges from 1398 to 5244 feet. Elevation mean: 2431 Feet General purpose display of elevation data. You should not expect the contours to be exact. The vertical datum used is NAVD 88, but the accuracy of the LIDAR is about 25cm or about 10, however, using two foot contours might be pushing data beyond the intended accuracy. Refer to NCDOT-GIS and Flood Mapping Web sites NCDOT GIS Branch, based on the USGS DEM data. GIS web site: http://www.ncdot.org/planning/statewide/gis/ March 13, 2005 Henderson County - Contour 5 foot HC_Contours_10ft vector digital data withheld publication date March 13, 2005 Complete As Needed 0 0 0 0 0 0 0 0 -130 6684 Feet Contour, LIDAR, Flood LIDAR North Carolina None. USGS DEM data is not very good for creating contours. File Geodatabase Feature Class NC Department of Transportation GIS Help Desk (gishelp@dot.state.nc.us) Mailing Address

1587 Mail Service Center

Raleigh NC 27699-1587 USA (919)-212-6000 8AM-5PM M-F The original USGS DEM data was stored as 90 meter cells. ESRI ArcCatalog 9.2.4.1420 HC_Contours_10ft 0 0 0 0 1 -80.775587 -80.185201 35.869245 35.496706 1 en FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time GIS Help Desk (gishelp@dot.state.nc.us) NC Department of Transportation Mailing Address

1587 Mail Service Center

Raleigh NC 27699-1587 (919)-212-6000 20090623 http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile ISO 19115 Geographic Information - Metadata DIS_ESRI1.0 dataset Downloadable Data 12.084 12.084 002 withheld Local Area Network 12.084 File Geodatabase Feature Class Vector Simple Polyline FALSE 0 TRUE FALSE String 0 GCS_North_American_1983 NAD_1983_StatePlane_North_Carolina_FIPS_3200_Feet coordinate pair survey feet 0.000328 0.000328 Lambert Conformal Conic 34.333333 36.166667 -79.000000 33.750000 2000000.002617 0.000000 North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 Explicit elevation coordinate included with horizontal coordinates 0.000100 NAD_1983_StatePlane_North_Carolina_FIPS_3200_Feet 0 2 4532 20 7406 20 1 Z_FEET Z_FEET Number 4 HC_Contours_10ft Feature Class 0 Shape Shape Geometry 0 0 0 Feature geometry. ESRI Coordinates defining the features. OBJECTID OBJECTID OID 4 0 0 Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape_Length Shape_Length Double 8 0 0 Length of feature in internal units. ESRI Positive real numbers that are automatically generated. 20090623 ground condition AML process. Setting the environment variable "ARCMEMSIZE" to 268435456 might help performance, but only if you have 1GB of RAM with a large swap file. Arc Workstation 9; 2.4GHZ / 1 GB RAM; Program was successfully run on smaller systems and older version of Arc March 13, 2005 52 Minutes Contours are created from an elevation grid with the z values rounded to the nearest 1/10th of an foot. ************************************************************************************ TempElevationA = INT(RealElevation * 10 + 0.5) Resample 30 meter DEM data to fill in void areas. ************************************************************************************ TempDemResample = INT(RESAMPLE(Statewide30MeterDEM,20) + 0.5) Merge LIDAR with 30 meter DEM with LIDAR taking precedence. ************************************************************************************ TempElevationB = MERGE(TempElevationA, TempDemResample) OPTIONAL STEP: Resample grid to 10 feet instead of 20 feet. This with take the program four times longer to complete but gives a more accurate contour line by about 4 feet along the x,y. Output files will be about 20% larger. ************************************************************************************ TempElevationC = INT(RESAMPLE(TempElevationB,10,BILINEAR) + 0.5) Filter elevation to reduce the significance of anomalous mesh points. ************************************************************************************ ARC FILTER TempElevationC TempElevationD LOW Convert back to integer so each z value is at 1/10th of an foot. ************************************************************************************ TempElevationE = INT(TempElevationD + 0.5) Create Contour at every 40 feet to avoid arc limitation. Add 0.05 feet to avoid square lines that match the grid. Weed every 4 feet to reduce file size Output elevation field is set to "z-feet" Factor all contours by 0.10 to get feet instead of 1/10th of foot. ************************************************************************************ LATTICECONTOUR TempElevationE ContourLine 40 0.05 z-feet 4.0 0.10 Unsplit, Count Vertices, and remove short circluar lines ************************************************************************************ EDIT ContourLine ; SELECT( fnode# = tnode# and length < 200 and vertices < 20 ) or ( fnode# = tnode# and length < 80 ) ; DELETE Convert the "z-feet" to an integer. Repeat until all contours are created. ************************************************************************************ Merge all contours and then create 20, 10, 5 and 2 foot files. Dataset copied. withheld 20090715 10160600 You should not expect the contours to be exact. The vertical datum used is NAVD 88, but the accuracy of the LIDAR is about 25cm or about 10, however, using two foot contours might be pushing data beyond the intended accuracy.