Identification_Information: Citation: Citation_Information: Originator: Atlanta Regional Commission (ARC) Publication_Date: 2010 Title: Dekalb County, GA Lidar Derived DTM and TIN 2010 Edition: 1.0 Geospatial_Data_Presentation_Form: Point and vector digital data Publication_Information: Publication_Place: Decatur, GA Publisher: Dekalb County, GA Description: Abstract: This metadata record describes the DTM comprised of classified aerial lidar elevation points, photogrammetrically compiled breaklines and the derived TIN for Dekalb County, GA Purpose: The lidar DEM data was collected for the Dekalb County, GA area. All lidar returns were classified using the default classes of Terrascan processing software for Unclassified Points (class 1), Ground points (class 2), Water points (class 9), Overlap points (class 12). The lidar ground points are supplemented with photogrammmetrically compiled breaklines from digital imagery collected during the same project time frame as the lidar. The ground class points, often refered to as "bald earth" are then used as an input to proprietary and publicly available processing software to generate a Triangulated Irregular Network (TIN) model. Classified lidar DEMs and derived TIN models are useful for a variety of applications, such as aiding in contour generation, development of digital surface models, 3D modeling, flood plane mapping, viewshed analysis and the production of orthophotos. Time_Period_of_Content: Time_Period_Information: Multiple_Dates/Times: Single_Date/Time: Calendar_Date: 20100102 Single_Date/Time: Calendar_Date: 20100103 Currentness_Reference: Ground condition Status: Progress: Complete Maintenance_and_Update_Frequency: Unknown Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -84.35091417 East_Bounding_Coordinate: -84.02334971 North_Bounding_Coordinate: 33.97061816 South_Bounding_Coordinate: 33.61447836 Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: Digital terrain model Theme_Keyword: DTM Theme_Keyword: LiDAR Theme_Keyword: mapping Theme_Keyword: "bare earth" Theme_Keyword: mass points Theme_Keyword: topography Theme_Keyword: Triangulated Irregular Network Theme_Keyword: TIN Place: Place_Keyword_Thesaurus: Dekalb County Place_Keyword: Dekalb County Place_Keyword: Decatur Place_Keyword: Dunwoody Place_Keyword: Doraville Place_Keyword: Chamblee Place_Keyword: Pine Lake Place_Keyword: Clarkston Place_Keyword: Avondale Place_Keyword: Stone Mountain Place_Keyword: Tucker Place_Keyword: Atlanta Place_Keyword: Belvedere Park Place_Keyword: Panthersville Place_Keyword: Lithonia Place_Keyword: Georgia Access_Constraints: Unknown Use_Constraints: Unknown Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Stacy Grear Contact_Organization: Dekalb County GIS Department Contact_Position: Acting Director Contact_Address: Address_Type: Mailing and physical address Address: 1300 Commerce Drive, Suite 600 City: Decatur State_or_Province: GA Postal_Code: 30030 Country: U.S.A. Contact_Voice_Telephone: 404-371-3619 Contact_Facsimile_Telephone: 404-371-3211 Contact_Electronic_Mail_Address: scgrear@co.dekalb.ga.us will change to scgrear@dekalbcountyga.gov on July 1, 2010 Hours_of_Service: 8:30 - 5:00 pm Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Attribute accuracy is tested in the LiDAR processing stage. After classification of the LiDAR data, the 'bald earth' point class is compared to ground control collected within the project area. Logical_Consistency_Report: LiDAR data is collected within the project area, processed and verified against control. Completeness_Report: LiDAR data is collected for the project area. Post processing of the simultaneously acquired GPS/INS is performed and applied to the laser returns to output a point cloud in the specified project coordinate system and datums. The point cloud data is then subjected to automated classification routines to assign all points in the point cloud to ground, water, overlap and unclassified point classes. Anomalous laser returns that occur infrequently are removed entirely from the data set. The ground class points are then compared to surveyed ground control to develop an accuracy measure of the laser terrain data. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal positional accuracy for LiDAR is dependent upon the quality of the GPS/INS solution, sensor calibration and ground conditions at the time of data capture. The standard system results for horizontal accuracy are less than 1 meter. Quantitative_Horizontal_Positional_Accuracy_Assessment: Horizontal_Positional_Accuracy_Value: 1 Horizontal_Positional_Accuracy_Explanation: This value is computed by comparing ground control to an intensity based image derived from the classified LiDAR data and represents the RMSE of residuals on controls within the project area. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: Vertical positional accuracy for LiDAR is dependent upon the quality of the GPS/INS solution, sensor calibration and ground conditions at the time of data capture. The vertical accuracy for this project was tested with a resultant RMSE of 0.057 meter (0.188 feet). Quantitative_Vertical_Positional_Accuracy_Assessment: Vertical_Positional_Accuracy_Value: 0.057 Vertical_Positional_Accuracy_Explanation: This value is computed by comparing ground control elevation to the classified LiDAR ground surface and represents the RMSE of residuals on controls within the project area. Units = meters. Lineage: Source_Information: Source_Citation: Citation_Information: Originator: Kucera International Inc. Publication_Date: Unpublished material Title: LiDAR Data Edition: 1.0 Geospatial_Data_Presentation_Form: Remote sensing image Publication_Information: Publication_Place: None Publisher: None Type_of_Source_Media: disc Source_Time_Period_of_Content: Time_Period_Information: Multiple_Dates/Times: Single_Date/Time: Calendar_Date: 20100102 Single_Date/Time: Calendar_Date: 20100103 Source_Currentness_Reference: Ground condition Source_Citation_Abbreviation: LIDAR Source_Contribution: Aerial LiDAR and GPS/IMU data was recorded for the defined project area. Source_Information: Source_Citation: Citation_Information: Originator: Kucera International Inc. Publication_Date: Unpublished material Title: Aerial Digital Imagery Edition: 1.0 Geospatial_Data_Presentation_Form: Remote sensing image Publication_Information: Publication_Place: None Publisher: None Type_of_Source_Media: disc Source_Time_Period_of_Content: Time_Period_Information: Multiple_Dates/Times: Single_Date/Time: Calendar_Date: 20100218 Single_Date/Time: Calendar_Date: 20100219 Single_Date/Time: Calendar_Date: 20100220 Single_Date/Time: Calendar_Date: 20100221 Source_Currentness_Reference: Ground condition Source_Citation_Abbreviation: IMG Source_Contribution: New digital aerial imagery and GPS/IMU data was recorded for the defined project area. Source_Information: Source_Citation: Citation_Information: Originator: Kucera International, Inc. Publication_Date: 2010 Title: Ground control Edition: 1.0 Geospatial_Data_Presentation_Form: tabular digital data Publication_Information: Publication_Place: None Publisher: None Type_of_Source_Media: disc Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2010 Source_Currentness_Reference: Ground condition Source_Citation_Abbreviation: CONT Source_Contribution: Targeted ground control is used to create a digital control file and control report as well as QC check of LiDAR accuracy. Predefined points (NGS when available) within the project area are targeted. Source_Information: Source_Citation: Citation_Information: Originator: Kucera International, Inc. Publication_Date: 2010 Title: Triangulated Irregular Network Edition: 1.0 Geospatial_Data_Presentation_Form: Vector digital data Publication_Information: Publication_Place: None Publisher: None Type_of_Source_Media: disc Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2010 Source_Currentness_Reference: Ground condition Source_Citation_Abbreviation: TIN Source_Contribution: Using the lidar elevation points and compiled breaklines as inputs, a Triangulated Irregular Network (TIN) is generated using ESRI ArcGIS software. Process_Step: Process_Description: At selected locations throughout the site, accurate GPS coordinates and elevations are surveyed and the points are marked with targets. Source_Used_Citation_Abbreviation: None Process_Date: 2010 Source_Produced_Citation_Abbreviation: CONT Process_Step: Process_Description: New LiDAR data is captured for the project area using a Leica ALS60 LiDAR instrument in conjunction with a POSAV Applanix GPS/INS system mounted within a Piper Navajo twin engine airplane. Source_Used_Citation_Abbreviation: None Process_Date: 2010 Source_Produced_Citation_Abbreviation: LIDAR, GPS_RAW Process_Step: Process_Description: New aerial digital imagery with airborne GPS/IMU data is acquired for the project area. Source_Used_Citation_Abbreviation: None Process_Date: 2010 Source_Produced_Citation_Abbreviation: IMG Process_Step: Process_Description: The airborne GPS data is processed in Terratec TerraPos software and then combined with the IMU data in Applanix PosPAC software to determine the LiDAR sensor's angle and orientation in the terrain (project) coordinate system and datums during the survey. The same GPS/IMU processing is performed for the digital imagery to define the orientation parameters of the images to be used in stereo compilation of terrain breaklines. Source_Used_Citation_Abbreviation: GPS_RAW Process_Date: 2010 Source_Produced_Citation_Abbreviation: GPS_SOL Process_Step: Process_Description: LiDAR data is processed using the GPS/INS solution. Data is classified to produce: Class 1: unclassified points Class 2: ground points Class 9: water points Class 12: overlap points Source_Used_Citation_Abbreviation: CONT, GPS_SOL, LIDAR Process_Date: 2010 Source_Produced_Citation_Abbreviation: LAS Process_Step: Process_Description: The ground class of the processed lidar data is then compared to the ground control and elevation differences between the lidar surface and surveyed elevation are recorded in tabular form. Vertical accuracy statistices are then developed to produce vertical RMSE and overall accuracy estimates and reports. Source_Used_Citation_Abbreviation: CONT, LIDAR Process_Date: 2010 Source_Produced_Citation_Abbreviation: None Process_Step: Process_Description: Photogrammetrically compiled breaklines are compiled to supplement the lidar ground points. Source_Used_Citation_Abbreviation: IMG Process_Date: 2010 Source_Produced_Citation_Abbreviation: BREAK Process_Step: Process_Description: Water polygons are buffered to remove any lidar points within the polygon to flatten these surfaces. Source_Used_Citation_Abbreviation: BREAK, LIDAR Process_Date: 2010 Source_Produced_Citation_Abbreviation: DTM1 Process_Step: Process_Description: Breaklines are buffered to remove lidar surface points on or near the breakline. Source_Used_Citation_Abbreviation: LIDAR, BREAK Process_Date: 2010 Source_Produced_Citation_Abbreviation: DTM2 Process_Step: Process_Description: The Traingulated Irregular Network is generate with ESRI ArcGIS software. Source_Used_Citation_Abbreviation: DTM2 Process_Date: 2010 Source_Produced_Citation_Abbreviation: TIN Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Ring composed of chains SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Node, planar graph SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Link Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: State Plane Coordinate System 1983 State_Plane_Coordinate_System: SPCS_Zone_Identifier: 1002 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999900 Longitude_of_Central_Meridian: -84.166667 Latitude_of_Projection_Origin: 30.000000 False_Easting: 2296583.333333 False_Northing: 0.000000 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: Coordinate pair Coordinate_Representation: Abscissa_Resolution: 0.5 Ordinate_Resolution: 0.5 Planar_Distance_Units: U.S. Survey Foot Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983/86 Ellipsoid_Name: Geodetic Reference System 80 Semi-major_Axis: 6378137.000000 Denominator_of_Flattening_Ratio: 298.25722210088 Vertical_Coordinate_System_Definition: Altitude_System_Definition: Altitude_Datum_Name: North American Vertical Datum of 1988 Altitude_Resolution: 0.1 Altitude_Distance_Units: U.S. Survey Foot Altitude_Encoding_Method: Implicit coordinate Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Stacy Grear Contact_Organization: Dekalb County GIS Department Contact_Position: Acting Director Contact_Address: Address_Type: Mailing and physical address Address: 1300 Commerce Drive, Suite 600 City: Decatur State_or_Province: GA Postal_Code: 30030 Country: U.S.A. Contact_Voice_Telephone: 404-371-3619 Contact_Facsimile_Telephone: 404-371-3211 Contact_Electronic_Mail_Address: scgrear@co.dekalb.ga.us will change to scgrear@dekalbcountyga.gov on July 1, 2010 Hours_of_Service: 8:30 - 5:00 pm Resource_Description: Dekalb County, GA Lidar Derived DEM and TIN 2010 Distribution_Liability: Dekalb County provides the geographic data "as is". This organization makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. Also, this organization makes no warranty, either expressed or implied, regarding the condition of the product or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these files have been processed successfully on computers at this organization, no warranty is made by this organization regarding the use of these data on any other system, nor does the fact of distribution constitute or imply such a warranty. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: TIFF (.tif) ESRI TIN Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: Contact Dekalb County GIS Department Access_Instructions: Contact Dekalb County GIS Department Offline_Option: Offline_Media: CD-ROM, DVD Recording_Format: ISO 9660 Fees: Contact Dekalb County GIS Department Ordering_Instructions: Contact Dekalb County GIS Department Available_Time_Period: Time_Period_Information: Single_Date/Time: Calendar_Date: 2010 Metadata_Reference_Information: Metadata_Date: 2010 Metadata_Review_Date: 2010 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Stacy Grear Contact_Organization: Dekalb County GIS Department Contact_Position: Acting Director Contact_Address: Address_Type: Mailing and physical address Address: 1300 Commerce Drive, Suite 600 City: Decatur State_or_Province: GA Postal_Code: 30030 Country: U.S.A. Contact_Voice_Telephone: 404-371-3619 Contact_Facsimile_Telephone: 404-371-3211 Contact_Electronic_Mail_Address: scgrear@co.dekalb.ga.us will change to scgrear@dekalbcountyga.gov on July 1, 2010 Hours_of_Service: 8:30 - 5:00 pm Metadata_Standard_Name: FGDC CSDGM Metadata_Standard_Version: FGDC-STD-001-1998