Identification_Information: Citation: Citation_Information: Originator: U.S. Geological Survey Originator: Teale Data Center GIS Solutions Group Originator: California Department of Fish and Game Publication_Date: Unknown Title: Hillshade, 30 Meter Resolution Geospatial_Data_Presentation_Form: remote-sensing image Online_Linkage: \\Molib01\GIS_Library\Elevation\Land\Hillshades\0030m_NED\hil30m_v1.sid Description: Abstract: Hillshade image based on the National Elevation Dataset (NED) at 30 meter resolution. This is a statewide version that is clipped to the California state border. Purpose: To display topography, landforms, etc. Supplemental_Information: Converted to California Teale Albers NAD83 by the California Department of Fish and Game -- BEGIN ORIGINAL METADATA - THIS INFORMATION MAY NOT BE CURRENT -- CALIFORNIA DEPARTMENT OF FISH AND GAME (DFG) GIS METADATA Digital Elevation Model - Hillshade (Shaded Relief) Version 30 Meter Resolution DATA TYPES: image, grid METADATA DATE: 2002.05.24 RELATED DATA: hil30m = statewide grid version hil30m_ = alternate extent grid version *.clr = optional grid colormap file *.tif = TIFF image version *.tfw = TIFF image world file *.sid = MrSID image version *.sdw = MrSID image world file *.txt = metadata file NAMING CONVENTION: = alternate extent property, such as: - DFG Regional clipped dataset (r1 = Region 1, etc.) - Buffered or extended dataset (b = beyond CA border) UPDATES: 2002.05.24 - noted projection parameters in Teale metadata. DATA DESCRIPTION: The 30-meter resolution hillshade datasets are based on the USGS National Elevation Dataset (NED) as explained in the attached metadata provided by the Teale Data Center GIS Solutions Group (Teale). The California Department of Fish and Game (DFG) Information Technology Branch (ITB) GIS Service Center mosaicked northern and southern California digital elevation models (DEMs) provided by Teale (z-units in integer feet), then generated hillshade grids and images using ArcInfo Workstation software, and clipped the data to various extents. For further information about the hillshade algorithm used, please refer to the "hillshade" documentation within the ArcInfo Workstation Grid or ArcView/ArcGIS Spatial Analyst software help files. State border clipping was performed using a outline version of the Teale Data Center "county" coverage (equivalent to USGS 1:100,000-scale digital line graph). The California Department of Fish and Game makes no warranty as to the suitability of these datasets for any purpose. GRID DATA DICTIONARY: Structure for grid attribute table ITEM NAME DESCRIPTION VALUE Shade value COUNT Frequency of VALUE VIEWING TIPS: Grid as an image: The grid versions can be viewed with some GIS software programs as an image. Some ESRI GIS programs allow you to view the grid with a predefined color ramp (an optional .clr file provides this automatically; it must remain in the same workspace and retain the same root name as the grid). In ArcView 3.x, the NODATA value color assignment can be made transparent from the image legend editor - colormap dialog. Grid as a grid: The grid versions can be viewed and queried using raster assessment software such as ESRI's Spatial Analyst or Grid extensions. ACCESS LIMITATIONS: None. These datasets are in the public domain and may be freely redistributed. DFG CONTACT: Will Patterson 916-323-1484, wpatters@dfg.ca.gov --- begin Teale metadata for NED 30 meter DEMs --- LIBRARY : LAYER NAME : LATTICE NAME : D LOCATION : /callib/dem24k LATTICE DESCRIPTION: The DEM lattices were imported from the 1:24,000 scale 1 arc-second (1 second) US Geological Survey (USGS) Digital Elevation Models (DEMs) extracted from the USGS National Elevation Dataset (NED). When projected from Decimal Degrees to Albers, cell cizes were set to 30 meters, equivalent to the standard USGS DEMs that were primarily used to create the NED. COMPLETENESS: The DEMs cover the entire state of California, plus neighboring portions of Oregon, Nevada, and Arizona. The DEMs are stored as Arc/Info GRIDs that cover 1 degree of latitude and longitude. The GRIDs overlap the degree boundaries to the extent required to make a rectangle in the Albers projection. This means that adjacent GRIDs overlap, however the data values are identical in the overlap areas. Thus, when merging adjacent DEMs, it makes no difference which DEM takes preference, and no averaging is required. Also available is a single statewide seamless DEM clipped to the 1:100,000 scale state boundary. Areas outside the state or coastline have ben set to NO DATA. VITAL STATISTICS: Quad-based metadata provided by USGS are stored in two polygon-based shapefiles: meta_a (albers projection), and meta_dd (decimal degrees). These metadata describe each of the DEMs that were used to create the NED. Horizontal Datum: NAD27 (spheroid: Clarke 1866) Vertical Datum: NGVD 29 Projection: Albers conic equal area Units: Meters 1st Std. Parallel: 34 00 00 (34.0 degrees N) 2nd Std. Parallel: 40 30 00 (40.5 degrees N) Longitude of Origin: -120 00 00 (120.0 degrees W) Latitude of Origin: 00 00 00 (0.0 degrees) False Easting (x shift): 0 False Northing (Y shift): -4000000 Source: U.S Geological Survey Source Media: CD ROM Data Scale: 1:24,000 Data Resolution: 30 meters Source Ground Unit: Meters Source Z Unit: Meters Capture Method: Various (scan techniques) Source Accuracy: Because elevation postings model a surface and do not represent specific features, horizontal accuracy is difficult to measure and is not stated by the USGS. 7 meters is the desired vertical Conversion Software: ARC/INFO Rev 7.2.1 Data Structure: Grid cell-based ARC/INFO Coverage Type: Lattice ARC/INFO Precision: Double ARC/INFO Tolerances: Not applicable Number of Features: Approximately 11.25 million per degree block (Approximately 3000 columns by 3750 rows) Layer Size: Average 20 MB per degree block Processing platform: Sun Sparc 3000 workstation Data Completed: January 2000 NAMING CONVENTION: Lattice names begin with a "d" and are based on the latitude and longitude of the southeast corner of the degree block. For example, the southeast corner of lattice "d36121" is located at latitude 36 00 00, longitude -121 00 00. ADDITIONAL PROCESSING NOTES: Source: The DEMs were extracted from the USGS National Elevation Dataset, described by USGS as "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. One of the effects of the NED processing steps is a much-improved base of elevation data for calculating slope and hydrologic derivatives.". The DEMs were received as 7 Arc/Info GRIDs that seamlessly mosaic (because they were extracted from a seamless GRID) with horizontal coordinates in decimal degrees and vertical units in floating point meters. The following processes were applied to the seven DEMs: 1. Converted to integer centimeters (in order to preserve vertical resolution but reduce storage requirements). 2. Mosaicked into a single statewide DEM. 3. Projected to Albers equal area (horizontal units are meters, cell size 30 meters) using a bilinear resampling method. 4. Vertical units were converted to integer feet. Zunits: The final DEMs were stored with elevation values as integer feet in order to reduce storage requirements (integers require much less storage than floating point values), yet preserve some precision (feet are smaller units of measurement than meters). DATA QUALITY ASSESSMENT: The following are subjective comments regarding this data. These DEMs are a superior product to the 30 meter DEMs traditionally available from USGS. As described above, these have been processed to remove production artifacts, edgematched, and any interquad gaps filled in. These have been generated from the best available DEMs, though the horizontal resolution of any 10 meter DEMs has been lost by resampling to 1 arc-second. These are better than the standard DEM product for calculating hydrologic deriviatives, but cannot be considered a hydrologically correct DEM. ADDITIONAL INFORMATION: Additional information is available from the USGS document "Digital Elevation Models, Data Users Guide". This can be ordered from: Earth Science Information Center U.S. Geological Survey 507 National Center Reston, Virginia 22092 (703) 648-6045 Or it is available online at: http://edcwww.cr.usgs.gov/Webglis/glisbin/guide.pl/glis/hyper/guide/usgs_dem DATA CONTACT: Contact Name: Andy Richardson Contact's Phone: 916-263-3649 --- end Teale metadata for NED 30 meter DEMs --- -- END ORIGINAL METADATA -- Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -124.506139 East_Bounding_Coordinate: -113.498494 North_Bounding_Coordinate: 42.068969 South_Bounding_Coordinate: 32.423617 Keywords: Theme: Theme_Keyword_Thesaurus: none Theme_Keyword: elevation Theme_Keyword: shaded relief Theme_Keyword: topography Place: Place_Keyword_Thesaurus: none Place_Keyword: California Access_Constraints: none Use_Constraints: none Native_Data_Set_Environment: Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 3; ESRI ArcCatalog 8.3.0.800 Data_Quality_Information: Lineage: Process_Step: Process_Description: Metadata imported. Source_Used_Citation_Abbreviation: S:\Elevation\Land\Hillshades\0030m_NED\hil30m_v1.sid.xml Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Pixel Row_Count: 35153 Column_Count: 30467 Vertical_Count: 1 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: Albers Conical Equal Area Albers_Conical_Equal_Area: Standard_Parallel: 34.000000 Standard_Parallel: 40.500000 Longitude_of_Central_Meridian: -120.000000 Latitude_of_Projection_Origin: 0.000000 False_Easting: 0.000000 False_Northing: -4000000.000000 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: row and column Coordinate_Representation: Abscissa_Resolution: 30.000000 Ordinate_Resolution: 30.000000 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.257222 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: Band_1 Attribute: Attribute_Label: ObjectID Attribute_Definition: Internal feature number. Attribute_Definition_Source: ESRI Attribute_Domain_Values: Unrepresentable_Domain: Sequential unique whole numbers that are automatically generated. Attribute: Attribute_Label: Value Attribute: Attribute_Label: Count Attribute: Attribute_Label: Green Attribute: Attribute_Label: Blue Distribution_Information: Resource_Description: Downloadable Data Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Transfer_Size: 36.158 Metadata_Reference_Information: Metadata_Date: 20040204 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: California Department of Fish and Game Contact_Person: GIS Service Center Contact_Address: Contact_Electronic_Mail_Address: geodata@dfg.ca.gov Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Time_Convention: local time Metadata_Extensions: Online_Linkage: http://www.esri.com/metadata/esriprof80.html Profile_Name: ESRI Metadata Profile