New Jersey Geological Survey DGS99-4 Digital Elevation Grids for New Jersey (1:100,000 scale) METADATA 1. IDENTIFICATION INFORMATION 1.1. CITATION Digital Elevation Grids for New Jersey (1:100,000 scale) Compiled by Gregory C. Herman, 1999 N.J. Geological Survey Digital Geodata Series DGS99-4 1.2. DESCRIPTION 1.2.1. ABSTRACT A set of ARC/INFO GRID digital elevation themes with 100-foot cells has been compiled for New Jersey. These data are modified from the U.S. Geological Survey (USGS) 30-meter Digital Elevation Model data. DGS99-4 includes a set of nine elevation grids, an associated set of nine shaded-relief (hillshade) grids, and ArcView shade legends for project use. The grids are georegistered to the NAD83 N.J. State Plane Coordinate system. Elevation values are integer feet. The data are clipped to the NJDEP New Jersey State boundary theme, and to a set of nine, 30-minute (longitudinal)polygons covering New Jersey. 1.2.2. LIST OF DIRECTORIES AND BRIEF DESCRIPTION 1.2.2.1 ELEVATION GRIDS All grids are ARC/INFO (v.7.x) GRID data format. Elevation grids have grid-cell elevation values in feet. ********************************************************* NAME DESCRIPTION SIZE --------- ----------------------------------- ------ njdem100 - Statewide theme 25.3MB nj100ft1 - 30-minute polygon No. 1 (Newton) 3.96MB nj100ft2 - 30-minute polygon No. 2 (Paterson) 2.62MB nj100ft3 - 30-minute polygon No. 3 (Flemington) 5.03MB nj100ft4 - 30-minute polygon No. 4 (Newark) 2.44MB nj100ft5 - 30-minute polygon No. 5 (Trenton) 2.12MB nj100ft6 - 30-minute polygon No. 6 (Freehold) 2.28MB nj100ft7 - 30-minute polygon No. 7 (Bridgeton) 3.34MB nj100ft8 - 30-minute polygon No. 8 (Long Beach) 2.24MB nj100ft9 - 30-minute polygon No. 9 (Cape May) 1.21MB 1.2.2.2 HILLSHADE GRIDS All grids are ARC/INFO (v7.x) data format. Hillshade grids have grid-cell color values ranging from 0 to 254. NAME DESCRIPTION SIZE --------- ------------------------------------ ------ nj100hshd - Statewide theme nj100hs1 - 30-minute polygon No. 1 (Newton) 3.22MB nj100hs2 - 30-minute polygon No. 2 (Paterson) 2.67MB nj100hs3 - 30-minute polygon No. 3 (Flemington) 3.75MB nj100hs4 - 30-minute polygon No. 4 (Newark) 1.92MB nj100hs5 - 30-minute polygon No. 5 (Trenton) 1.76MB nj100hs6 - 30-minute polygon No. 6 (Freehold) 1.82MB nj100hs7 - 30-minute polygon No. 7 (Bridgeton) 2.64MB nj100hs8 - 30-minute polygon No. 8 (Long Beach) 1.63MB nj100hs9 - 30-minute polygon No. 9 (Cape May) 1.01MB 1.2.2.3 INFO directory (183KB) 1.2.3. LIST OF FILES AND BRIEF DESCRIPTION 1.2.3.1 INFO FILES The coverage extent (BND) represents the map extent of coordinates in the grid. All BND information for a grid is stored in the BND file. The STA table contains statistical data about a grid. The minimum, maximum, and mean, and standard deviation for the grid are stored as floating-point values in the STA table. An integer grid has a value attribute table (VAT) which stores attribute information for the set of cell values in a grid. NO. TYPE NAME RECS LENGTH -- ------------ ---- -- DF NJ100FT3.BND 1 32 DF NJ100FT3.STA 1 32 DF NJ100FT3.VAT 1281 8 DF NJDEM100.BND 1 32 DF NJDEM100.STA 1 32 DF NJDEM100.VAT 1795 8 DF NJ100FT1.BND 1 32 DF NJ100FT1.STA 1 32 DF NJ100FT1.VAT 1534 8 DF NJHSHD100.BND 1 32 DF NJHSHD100.STA 1 32 DF NJHSHD100.VAT 255 8 DF NJ100FT2.BND 1 32 DF NJ100FT2.STA 1 32 DF NJ100FT2.VAT 1484 8 DF NJ100FT4.BND 1 32 DF NJ100FT4.STA 1 32 DF NJ100HS1.BND 1 32 DF NJ100HS1.STA 1 32 DF NJ100HS1.VAT 251 8 DF NJ100HS2.BND 1 32 DF NJ100HS2.STA 1 32 DF NJ100HS2.VAT 254 8 DF NJ100HS3.BND 1 32 DF NJ100HS3.STA 1 32 DF NJ100HS3.VAT 213 8 DF NJ100HS4.BND 1 32 DF NJ100HS4.STA 1 32 DF NJ100HS4.VAT 233 8 DF NJ100HS5.BND 1 32 DF NJ100HS5.STA 1 32 DF NJ100HS5.VAT 144 8 DF NJ100HS6.BND 1 32 DF NJ100HS6.STA 1 32 DF NJ100HS6.VAT 108 8 DF NJ100HS7.BND 1 32 DF NJ100HS7.STA 1 32 DF NJ100HS7.VAT 83 8 DF NJ100HS8.BND 1 32 DF NJ100HS8.STA 1 32 DF NJ100HS8.VAT 57 8 DF NJ100HS9.BND 1 32 DF NJ100HS9.STA 1 32 DF NJ100HS9.VAT 66 8 DF NJ100FT4.VAT 970 8 DF NJ100FT5.BND 1 32 DF NJ100FT5.STA 1 32 DF NJ100FT5.VAT 480 8 DF NJ100FT6.BND 1 32 DF NJ100FT6.STA 1 32 DF NJ100FT6.VAT 372 8 DF NJ100FT7.BND 1 32 DF NJ100FT7.STA 1 32 DF NJ100FT7.VAT 215 8 DF NJ100FT8.BND 1 32 DF NJ100FT8.STA 1 32 DF NJ100FT8.VAT 219 8 DF NJ100FT9.BND 1 32 DF NJ100FT9.STA 1 32 DF NJ100FT9.VAT 114 8 1.2.3.2 COMPRESSED ARCHIVE (ZIP) FILES OF THE EXPORTED GRIDS Each compressed zip file contains an uncompressed ARC/INFO (v.7.x) export file (*.e00). SIZE SIZE NAME TILE NAME COMPRESSED UNCOMPRESSED ------------ ---------- ------ ------- nj100ft1.zip Newton 4.01MB 40.54MB nj100ft2.zip Paterson 2.67MB 31.39MB nj100ft3.zip Flemington 5.44MB 46.77MB nj100ft4.zip Newark 2.70MB 37.20MB nj100ft5.zip Trenton 2.59MB 46.84MB nj100ft6.zip Freehold 2.65MB 35.27MB nj100ft7.zip Bridgeton 4.00MB 54.69MB nj100ft8.zip Long Beach 2.38MB 44.90MB nj100ft9.zip Cape May 1.39MB 60.16MB nj100hs1.zip Newton 3.22MB 40.52MB nj100hs2.zip Paterson 2.67MB 31.39MB nj100hs3.zip Flemington 3.75MB 46.74MB nj100hs4.zip Newark 1.92MB 37.18MB nj100hs5.zip Trenton 1.76MB 46.84MB nj100hs6.zip Freehold 1.82MB 35.27MB nj100hs7.zip Bridgeton 2.46MB 54.69MB nj100hs8.zip Long Beach 1.63MB 44.90MB nj100hs9.zip Cape May 1.01MB 60.15MB 1.2.3.3 ArcView GRID THEME SHADE LEGENDS njdem100.avl (9KB) - Red monochromatic shade legend with 21 shades for 20, 100 ft elevation-range values and 1 "no data" value. nj100hshd.avl (5KB) - Black, brown, and white shade legend with 10 shades including 9 color ranges and one "no data" value 1.2.4. LIST OF KEYWORDS digital-elevation model, shaded-relief map, hillshade map, surface grid, topography, topographical relief, topographical surface model, 1.3. GEOGRAPHIC EXTENT 1.3.1 MAP EXTENT State of New Jersey, U.S.A. 1.4. CONTACTS INFORMATION Gregory Herman N.J. Dept. Environmental Protection Division of Science, Research, & Technology N. J. Geological Survey PO Box 427 Trenton, NJ 08625 phone: (609) 984-6587, email: gherman@dep.nj.gov ********************************************************* 2. DATA QUALITY INFORMATION 2.1. NAME OF DATA nj100dem, nj100ft1, nj100ft2, nj100ft3, nj100ft4, nj100ft5, nj100ft6, nj100ft7, nj100ft8, nj100ft9, nj100hshd , nj100hs1, nj100hs2, nj100hs3, nj100hs4, nj100hs5, nj100hs6, nj100hs7, nj100hs8, nj100hs9 2.1.1. DESCRIPTION OF THE TYPE OF DATA ARC/INFO (v.7.2.1) GRID themes are raster (cell-based) data with relational database attributes for each cell. 2.1.2. DATA SOURCE Originator: U.S. Geological Survey (USGS), EROS Data Center Publication_Date: 1999 Title: GRID NJ_DEM - National Elevation Database of NJ Edition: 1 Geospatial_Data_Presentation_Form: raster digital data Publication_Place: Sioux Falls, SD Publisher: U.S. Geological Survey Online_Linkage: http://edcnts12.cr.usgs.gov/ned/ned.html Source file: nj_dem.e00 (362MB) Contact_Organization_Primary: Jack Pflaumer Contact_Organization: U.S. Geological Survey Contact_Position: hydrologist Contact_Address: 810 Bear Tavern Road City: W. Trenton State_or_Province: NJ Postal_Code: 08628 Country: USA Contact_Voice_Telephone: 609-771-3918 Contact_Instructions: Contact via email Contact_Electronic_Mail_Address: pflaumer@usgs.gov The U.S. Geological Survey National Elevation Database (NED) is a seamless mosaic of best-available elevation data. The 7.5-minute elevation data for the conterminous United States are the primary initial source data. In addition to the availability of complete 7.5-minute data, efficient processing methods were developed to filter production artifacts in the existing data, convert to the NAD83 datum, edge-match, and fill slivers of missing data at quadrangle seams. Please contact the originator of the source theme listed above or the U.S. Geological Survey metadata file referenced in section 5.3. 2.1.3. DATA ORGANIZERS G.C. Herman 2.1.4. DATE OF COMPLETION December 12, 1999 2.1.5. DATA AUTOMATION A 100-foot, State Plane Coordinate, digital-elevation grid of New Jersey and bordering parts of New York State (see section 2.1.2) was obtained on Compact Disc from the offices of the U.S. Geological Survey, Water Resources Division, Trenton, NJ on 7/29/99. The grid was clipped to the N.J. Department of Environmental Protection state boundary coverage (staco). The grid-cell elevation values were converted from floating-point values to integers. A hillshade grid was computed from the statewide elevation grid using the ArcView Spatial Analyst extension with hillshade input parameters azimuth 315, and altitude 45. The statewide grids were then clipped to each of the nine 30-minute longitudinal polygons. Custom ArcView shade legends were created using the ArcView legend editor for layout production. 2.1.6 SPATIAL ACCURACY A test of the vertical spatial accuracy was conducted on the njdem100 coverage. The testing was conducted according the Federal Geographic Data Committee (FGDC) guidelines for reporting Geospatial Positions (FGDC-STD-007.3-1998). Njdem100 coverage tested 42.4869 feet vertical accuracy at the 95% confidence level. Test procedures: 1) Generated 37 random points within the NJ State boundary theme using the ArcView extension rand#gen.avx, with extension options set for 0 minimum distance to polygon boundary, and 0 minimum distance between points. At least 4 random points were generated within each 30-minute polygon. Five (5) points were used in the Cape May polygon. 2) Tested the accuracy of the grid elevation values against reference elevation values from the set of 1:24,000 scale U.S. Geological Survey 7-1/2 minute topographic quadrangles published by the N.J. Geological Survey (http://www.state.nj.us/dep/njgs/geodata/dge99-1.htm). Testing was conducted using the ArcView RMSEr.avx extension. 3) The test procedure involved consecutively locating check points on topographic elevation contour lines or benchmark locations located closest to the randomly generated points. The cumulative root-mean-square error (RMSEz)for 37 points tested at 21.667 ft. The vertical accuracy (RMSEz at the 95% confidence interval) was calculated to be equal to 42.4869 ft. using the formulae: vertical accuracy = RMSEz * 1.6449. ********************************************************* 3. SPATIAL DATA ORGANIZATION INFORMATION 3.1. NAME OF DATA nj100dem, nj100ft1, nj100ft2, nj100ft3, nj100ft4, nj100ft5, nj100ft6, nj100ft7, nj100ft8, nj100ft9, nj100hshd , nj100hs1, nj100hs2, nj100hs3, nj100hs4, nj100hs5, nj100hs6, nj100hs7, nj100hs8, nj100hs9 3.1 DATA STRUCTURE ARC/INFO grids are raster (cell-based) data with relational database attributes for each cell. Grids are stored within ARC/INFO workspaces; directory-level computer files containing grid and INFO subdirectories. Each grid possesses a directory-level computer file structure. Each categorical grid has an associated value attribute table (VAT) that is stored in the INFO relational database. Grids use a hierarchical tile-block structure. Each grid is first divided into uniform square units called tiles. Each tile represents an actual portion of geographic space. A tile is divided into blocks. Blocks are rectangular units with the x-axis direction longer than the y-axis direction. A block is made up of square cells arranged in a Cartesian matrix consisting of rows and columns. An ARC/INFO GRID is stored as a separate directory with associated tables and files containing specific information about the grid. Each GRID has the following set of files residing under the directory bearing the file name (for example, nj001): dblbnd.adf - table storing information about the grid boundary hdr.adf - binary file storing information about cell resolution and blocking factor log - file containing information about activity that has occurred on the grid sta.adf - INFO table containing statistics for the grid vat.adf - INFO table storing attributes associated with the zones of a grid w001001.adf - tile file that stores the cell data w001001x.adf - index file that indexes the blocks in the tile and log files In addition to these files, each grid includes two associated INFO files residing under the INFO directory within the root workspace. These INFO files are named sequentially within the workspace and include the arc####.dat and arc####.nit file names, where #### is a 4-digit numeral related to the sequence of entry within the ARC/INFO workspace. These INFO files are linked to the sta.adf and vat.adf files under the file name directory. 3.1.2 NUMBER OF SPATIAL OBJECTS 20 ARC/INFO Grids, 2 ArcView legend files, and 18 compressed archive files in a MS-Windows compatible ZIP format. ********************************************************* 4. SPATIAL REFERENCE INFORMATION 4.1 COMMON GRID PARAMETERS Scale = 1:100,000 Datum = NAD83 Coordinate System = NJ State Plane Units = feet Spheroid = GRS 1980 Projection = Polyconic Zone = 4701 4.2. GRID BOUNDARY PARAMETERS GRID XMIN XMAX YMIN YMAX -------- ---------- ---------- ---------- ---------- njdem100 193624.000 659524.000 35034.773 919434.773 nj100ft1 316458.625 492158.625 743657.875 919457.875 nj100ft2 492125.000 659525.000 743657.875 886657.875 nj100ft3 296863.938 492163.938 561513.250 744113.250 nj100ft4 492125.000 647525.000 561513.250 744113.250 nj100ft5 296203.906 492103.906 379384.469 561884.469 nj100ft6 492125.000 639225.000 379384.469 561984.469 nj100ft7 193624.000 421924.000 197369.234 380169.234 nj100ft8 421456.906 609456.906 197271.422 379671.422 nj100ft9 238599.156 519299.156 35034.773 198534.773 njhshd100 193624.000 659524.000 35034.773 919434.773 nj100hs1 316458.625 492158.625 743657.875 919457.875 nj100hs2 492125.000 659525.000 743657.875 886657.875 nj100hs3 296863.938 492163.938 561513.250 744113.250 nj100hs4 492125.000 647525.000 561513.250 744113.250 nj100hs5 296203.906 492103.906 379384.469 561884.469 nj100hs6 492125.000 639225.000 379384.469 561984.469 nj100hs7 193624.000 421924.000 197369.234 380169.234 nj100hs8 421456.906 609456.906 197271.422 379671.422 nj100hs9 238599.156 519299.156 35034.773 198534.773 ********************************************************* 5. ENTITY AND ATTRIBUTE INFORMATION 5.1 COMMON GRID PROPERTIES Grid Cell Size = 100 ft Attribute Data (bytes) = 8 5.2 UNIQUE GRID PROPERTIES NO. NO. NO. MIN. MAX MEAN STD. GRID VALUES ROWS COLUMNS VALUE VALUE VALUE DEV. -------- ---- ---- ---- ---- ---- ------- ------- njdem100 1795 8844 4659 -13 1802 223.922 291.464 nj100ft1 1534 1758 1757 248 1802 770.697 248.944 nj100ft2 1484 1430 1674 -8 1476 498.946 371.334 nj100ft3 1281 1826 1953 7 1302 423.290 267.895 nj100ft4 970 1826 1554 -13 960 137.333 132.956 nj100ft5 480 1825 1959 -1 478 85.527 60.578 nj100ft6 372 1826 1471 -3 371 91.991 53.914 nj100ft7 215 1828 2283 0 215 76.288 43.204 nj100ft8 219 1824 1880 -3 215 49.748 44.009 nj100ft9 114 1635 2807 -2 111 18.247 18.747 njhshd100 255 8844 4659 0 254 179.305 10.246 nj100hs1 251 1758 1757 0 153 179.066 20.628 nj100hs2 254 1430 1674 0 253 177.562 17.808 nj100hs3 213 1826 1953 35 254 178.662 14.093 nj100hs4 233 1826 1554 0 242 179.171 8.302 nj100hs5 144 1825 1959 91 239 179.732 4.319 nj100hs6 108 1826 1471 113 229 179.597 3.969 nj100hs7 83 1828 2283 131 215 179.802 2.772 nj100hs8 57 1824 1880 146 204 179.702 2.177 nj100hs9 66 1635 2807 138 220 179.770 1.536 5.3 LIST OF RELATED TEXT FILES AND LOOK-UP TABLES njdem.meta - Metadata file prepared for the source data by ther U.S. Geological Survey, Water Resources Division. Available upon request. ********************************************************* 6. DISTRIBUTION INFORMATION Data are available in a custom format or media upon written request to the N.J. Geological Survey. Please direct any requests to: State Geologist N.J. Geological Survey PO Box 427 Trenton, NJ 08625 ********************************************************* 7. METADATA REFERENCE INFORMATION 7.1 PUBLICATION DATE: 12-17-99 7.2 AUTHORS: G.C. Herman ********************************************************* 8. PUBLISHED REFERENCES Federal Geographic Data Committee, 1998, Geospatial Positional Accuracy Standards: FGDC-STD-007-1998, Washington, D.C., 4 Parts. U.S. Bureau of the Budget, 1947, United States National Map Accuracy Standrds: U.S. Bureau of the Budget, Washington, D.C. ********************************************************* 9. AUTHOR'S NOTES Although no threshold values for geopositional accuracy have yet been established for digital elevation data by New Jersey State authorities, the tested vertical accuracy of the njdem100 coverage implies applicability at a scale of 1:100,000 or larger based on the 1/2-contour accuracy guidelines set forth in the National Map Accuracy Standards (1947).