IMAGE.BARE_EARTH

Science Applications International Corporation (SAIC) 200907 Unknown IMAGE.BARE_EARTH_2008 SDE raster digital data Chantilly, VA Science Applications International Corp. (SAIC) Reflective Surface DEM Server=10.1.11.144; Service=5151; User=image; Version=SDE.DEFAULT IMAGE.BARE_EARTH_2008 LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser rangefinding, GPS positioning and inertial measurement technologies; LIDAR instruments are able to make highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures and vegetation. This data was collected at a resolution of 1 meter and includes reflective surface, last return, bare earth model and intensity data in separate data files. LIDAR data is used for 3D visualization, elevation based analysis and for feature extraction. Reflective surface data represents the DEM created by laser energy reflected from the first surface encountered by the laser pulse. Some energy may continue beyond this initial surface to be reflected by a subsequent surface as represented by the Last Return data. Intensity information is captured from the Reflective Surface pulse and indicates the relative energy returned to the sensor as compared to the energy transmitted. The Intensity image is not calibrated or normalized but indicates differences in energy absorption due to the the interaction of the surface materials with laser energy at the wavelength transmitted by the sensor. Bare earth model is created by identifying those returns that fall on the ground surface and interpolating a surface between these points. In this manner buildings and vegetation are removed from Bare Earth Model. This data set does not include bridges and overpasses in the Bare Earth model as the delineation point for these structures is not reliably discernable in the LiDAR data. en The year (and optionally month, or month and day) for which the data set corresponds to the ground. 20080312 20081223 ground condition Complete Irregular -77.125651 -76.903273 38.999587 38.787958 389115.783170 408378.783170 124475.365051 147960.365051 Light Distancing And Ranging LIDAR Digital Elevation Model DEM Average ground sample distance 1m 1meter resolution elevation model Surface of first measurable laser pulses detected by sensor Reflective Surface U.S. Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions (Federal Information Processing Standard (FIPS) 10-4): Washington, D.C., National Institute of Standards and Technology US U.S. Department of Commerce, 1987, Codes for the Indentification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standards (FIPS) 5-2): Washington, D.C., National Institute of Standards and Technology. DC City Washington None None. However, users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of it's limitations. National Geospatial-Intelligence Agency n/a US DOD Unclassified Information Unclassified - distribution limited by Point of Contact Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.2.6.1500 SDE Raster Dataset All IMG formatted image data are validated using commercial GIS software to ensure proper formatting and loading before delivery. This validation procedure ensures that data on delivery media is in correct physical format and is readable. LIDAR raster data is visually inspected for completeness to ensure that any gaps between flight lines or loss of signal represents less than 5% of required collection area. Areas of open water where loss of LIDAR signal is common are corrected to the best estimate of water level at time of collection. Areas of NODATA resulting from differences between required collection area and minimum bounding rectangle and/or areas of missing data are coded -999 to ensure compatibility between ESRI production software and ERDAS delivery format. LIDAR is self-illuminating and has minimal cloud penetration capability. Water vapor in steam plumes or particulates in smoke may cause reflection of LIDAR signals and loss of elevation information beneath these plumes. Glass structures and roofs may appear transparent to the LIDAR signal and therefore may not register on the reflective surface. Some asphalt formulations have been shown to absorb topographic LIDAR wavelength energy resulting in "pitting" of roof surfaces using this material. Horizontal accuracy of the source LIDAR data can be characterized by the rule of thumb of 1/2000th of flying height or roughly 0.5 meters for this collect. Spot checks in the field routinely are measured at 1/4000th of flying height but are not formally characterized. Better than 1 m Estimated horizontal accuracy of extracted feature data. Informal assessments indicate that horizontal accuracy is better than 1 m based on comparisons with ortho imagery. The vertical accuracy was tested following the National Standards for Spatial Data Accuracy. Washington DC: Based on a total of 45 control points, the average error between the bare earth LiDAR coverage and the control was 0.004m with a root mean square error (RMSE) of 0.107m. Washington DC Mall Area: The vertical accuracy was tested following the National Standards for Spatial Data Accuracy. Based on a total of 7 control points, the average error between the bare earth LiDAR coverage and the control was 0.034 m with a root mean square error (RMSE) of 0.095 m. 0.034 m Average error between Bare Earth LiDAR coverage and control 0.107 m root mean square error (RMSE) Woolpert Inc Unpublished Material LIDAR data collection Washington DC: - Type of Scanner = Leica Systems ALS50 II - Data Acquisition Height = 6,500-feet AGL - Scanner Field of View = 44 degrees - Scan Frequency = 41.3 Hertz - Pulse Repetition Rate - 114.6 Kilohertz - Aircraft Speed = 140 KIAS - Swath Width = 1600-meters - Nominal Ground Sample Distance = 3.0-feet - Number of Returns Per Pulse = 2 (first and last) - Distance Between Flight Lines = 1165-meters Washington DC Mall Area: - Type of Scanner = Leica Systems ALS50 II - Data Acquisition Height = 4,000-feet AGL - Scanner Field of View = 40 degrees - Scan Frequency = 36.5 Hertz - Pulse Repetition Rate - 72.0 Kilohertz - Aircraft Speed = 126 KIAS - Swath Width = 887.6-feet - Nominal Ground Sample Distance = 3.0-feet - Number of Returns Per Pulse = 2 (first and last) - Distance Between Flight Lines = 621-feet 3000 DVD-ROM 20080312 20081223 ground condition LIDAR Raw spatial elevation information Woolpert LLP Unpublished Material Collection System Calibration The ALS50 calibration and system performance is verified on a periodic basis using Woolpert's calibration range. The calibration range consists of a large building and runway. The edges of the building and control points along the runway have been located using conventional survey methods. Inertial measurement unit (IMU) misalignment angles and horizontal accuracy are calculated by comparing the position of the building edges between opposing flight lines. The scanner scale factor and vertical accuracy is calculated through comparison of LiDAR data against control points along the runway. Field calibration is performed on all flight lines to refine the IMU misalignment angles. IMU misalignment angles are calculated from the relative displacement of features within the overlap region of adjacent (and opposing) flight lines. The raw LiDAR data is reduced using the refined misalignment angles. 20080312 20081223 Process Step: Production Narrative: Using a Leica Systems ALS50 Light Detection And Ranging (LiDAR) system, 259 flight lines of high density (submeter ground sample distance) data were collected over Washington DC (approximately 8,253 square kilometers). Two returns were recorded for each laser pulse along with an intensity value for each return. A total of nine missions were flown over a nine day period: October 31, 2008, November 10, 2008, November 11, 2008, December 6, 2008, December 7, 2008, December 8, 2008, December 13, 2008 and December 23, 2008. One airborne global positioning system (GPS) base station was used to support the LiDAR data acquisition: Woolpert placed base station (Woolpert_Manassas). In addition, 45 control points surveyed through static methods were tied into the Woolpert placed base station. Another 6 flight lines of high density (submeter ground sample distance) data were collected over Washington DC Mall area (approximately 43.5 square kilometers). Two returns were recorded for each laser pulse along with an intensity value for each return. A total of two missions were flown over a two day period: March 12, 2008 and March 21, 2008. Two airborne global positioning system (GPS) base stations were used to support the LiDAR data acquisition: GAI B (NGS point) and USNO (NGS CORS). In addition, twelve control points were surveyed through static methods tied into NGS control point GAI B and USNO. Airborne GPS data was differentially processed and integrated with the post processed IMU data to derive a smoothed best estimate of trajectory (SBET). The SBET was used to reduce the LiDAR slant range measurements to a raw reflective surface for each flight line. The coverage was classified to extract a bare earth digital elevation model (DEM) and separate last returns. Four layers of coverage were delivered in the ArcINFO ArcGrid binary format: reflective surface, bare-earth, last return and intensity. System Parameters: Washington DC: - Type of Scanner = Leica Systems ALS50 II - Data Acquisition Height = 6,500-feet AGL - Scanner Field of View = 44 degrees - Scan Frequency = 41.3 Hertz - Pulse Repetition Rate - 114.6 Kilohertz - Aircraft Speed = 140 KIAS - Swath Width = 1600-meters - Nominal Ground Sample Distance = 3.0-feet - Number of Returns Per Pulse = 2 (first and last) - Distance Between Flight Lines = 1165-meters Washington DC Mall Area: - Type of Scanner = Leica Systems ALS50 II - Data Acquisition Height = 4,000-feet AGL - Scanner Field of View = 40 degrees - Scan Frequency = 36.5 Hertz - Pulse Repetition Rate - 72.0 Kilohertz - Aircraft Speed = 126 KIAS - Swath Width = 887.6-feet - Nominal Ground Sample Distance = 3.0-feet - Number of Returns Per Pulse = 2 (first and last) - Distance Between Flight Lines = 621-feet 200803, 200812 System Calibration Procedure: The ALS50 calibration and system performance is verified on a periodic basis using Woolpert's calibration range. The calibration range consists of a large building and runway. The edges of the building and control points along the runway have been located using conventional survey methods. Inertial measurement unit (IMU) misalignment angles and horizontal accuracy are calculated by comparing the position of the building edges between opposing flight lines. The scanner scale factor and vertical accuracy is calculated through comparison of LiDAR data against control points along the runway. Field calibration is performed on all flight lines to refine the IMU misalignment angles. IMU misalignment angles are calculated from the relative displacement of features within the overlap region of adjacent (and opposing) flight lines. The raw LiDAR data is reduced using the refined misalignment angles. 200803, 200812 Post Processing Procedure: Airborne GPS is differentially processed using the GrafNAV V4.40 software by Waypoint Consulting of Calgary, Alberta, Canada. The PDOP and distance separation by day is as follows: March 12, 2008 (GAI B): Average PDOP = 1.7 Average Distance Separation: 40 km March 21, 2008 (USNO): Average PDOP = 1.5 Average Distance Separation: 15 km October 31, 2008: Average PDOP = 1.5 Average Distance Separation: 70 km November 10, 2008: Average PDOP = 1.5 Average Distance Separation: 45 km November 11, 2008: Average PDOP = 1.3 Average Distance Separation: 34 km December 6, 2008: Average PDOP = 1.4 Average Distance Separation: 30 km December 7, 2008: Average PDOP = 1.4 Average Distance Separation: 30 km December 8, 2008: Average PDOP = 1.5 Average Distance Separation: 95 km December 13, 2008_A: Average PDOP = 1.3 Average Distance Separation: 45 km December 13, 2008_B: Average PDOP = 1.3 Average Distance Separation: 50 km December 23, 2008: Average PDOP = 1.5 Average Distance Separation: 60 km IMU data is processed using the IPAS Pro software by Leica. The reflective surface is derived using the ALS Post Processor software by Leica Geosystems GIS & Mapping Division of Atlanta, Georgia. The classification and quality control (QC) of LiDAR data is carried out using a combination of Woolpert proprietary software and TerraScan software by Terrasolid Limited of Helinski, Finland. 200803, 200812 Data Consolidation and Review: Raw LiDAR data is delivered to contractor by collector. Four layers of coverage were delivered in the ArcINFO ArcGrid binary format: reflective surface, bare-earth, last return and intensity. These tiles are converted & merged into larger ESRI GRID files and reviewed for quality and consistency. Preliminary Bare Earth surface is reviewed and edited as required to remove or add features to bare earth surface as required by cartographic requirements 200907 Data Conversion: Merged tiles of ESRI GRID formatted data are converted to ERDAS Imagine image format. Areas coded as NODATA in ESRI GRID format are converted to -999 in ERDAS IMG format. IMG files are encoded with projection information for proper zone and datum as part of conversion process. Metadata is added. 200907 Metadata imported. W:\LIDAR_CITIES\DC_01\metadata\reflective_surface.xml Metadata imported. G:\Washington_DC_2009\reflective_surface_return.xml 20091002 14261200 Metadata imported. Z:\Lidar2008_Pilot\DCReflectiveSurface_Project.img.xml 20100927 15282400 0 Raster Pixel 23485 19263 1 1.000000 1.000000 32 Upper Left FALSE LZ77 1 pixel codes TRUE SDR row and column 1.000000 1.000000 meters North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 GCS_North_American_1983 NAD_1983_StatePlane_Maryland_FIPS_1900 North American Vertical Datum of 1988 .01 meters Explicit elevation coordinate included with horizontal coordinates Band_1 Single Band Image - IMAGINE Format ERDAS ObjectID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Value Elevation value, in meters ERDAS Unknown Unknown meters .01 Count Number of cells with this value ERDAS Elevation statistics captured internally in IMAGINE data structure National Geospatial-Intelligence Agency DVD No warranty expressed or implied is made by provider regarding the utility or the data on any other system, nor shall the act of distribution constitute any such warranty. ERDAS Imagine format on DVD 0.000 0.000 None Upon request from distributor. Data release caveats may apply Variable 20100927 National Geospatial-Intelligence Agency (NGA) The person responsible for the metadata information. 21300 Sunrise Valley Drive Reston VA 20191 USA l. FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile en 20100927 15282400 FALSE 20230928 10314900 20230928 10314900 CopyRaster "E:\Lidar_Data_2009\Reflective Surface\DC_reflective_surface_11.img" C:\Client_Maps\LidarClip\DCClip\DCclip.mdb\DC_reflective_surface_11 # # # NONE NONE # Clip C:\Client_Maps\LidarClip\DCClip\DCclip.mdb\DC_reflective_surface_11 "315917.796802463 4295382.71283471 334679.028252143 4318459.94418391" C:\Client_Maps\LidarClip\DCClip\DCclip.mdb\DC_reflective_surface_11_Cli C:\Client_Maps\LidarClip\DCClip\DCclip.mdb\DCBndyPly # ClippingGeometry Clip C:\Client_Maps\LidarClip\DCClip\DCclip.mdb\DC_reflective_surface_11_Cli "324680.258454669 4303680.78504558 326314.972338395 4305315.4989454" P:\Lidar2008_Pilot\DCReflectiveSurface.img C:\Client_Maps\Ortho_Pilot_2010\Tilelayout.shp # NONE ProjectRaster P:\Lidar2008_Pilot\DCReflectiveSurface.img P:\Lidar2008_Pilot\DCReflectiveSurface_ProjectR.img PROJCS['NAD_1983_StatePlane_Maryland_FIPS_1900',GEOGCS['GCS_North_American_1983',DATUM['D_North_American_1983',SPHEROID['GRS_1980',6378137.0,298.257222101]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]],PROJECTION['Lambert_Conformal_Conic'],PARAMETER['False_Easting',400000.0],PARAMETER['False_Northing',0.0],PARAMETER['Central_Meridian',-77.0],PARAMETER['Standard_Parallel_1',38.3],PARAMETER['Standard_Parallel_2',39.45],PARAMETER['Latitude_Of_Origin',37.66666666666666],UNIT['Meter',1.0]] NEAREST 1 NAD_1983_To_WGS_1984_1 # PROJCS['WGS_1984_UTM_Zone_18N',GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]],PROJECTION['Transverse_Mercator'],PARAMETER['False_Easting',500000.0],PARAMETER['False_Northing',0.0],PARAMETER['Central_Meridian',-75.0],PARAMETER['Scale_Factor',0.9996],PARAMETER['Latitude_Of_Origin',0.0],UNIT['Meter',1.0]] BARE_EARTH_2008.tif file://\\Gisimgprd1\e\Productionfiles\Lidar_2008\BARE_EARTH_2008.tif Local Area Network 389115.783170 408378.783170 124475.365051 147960.365051 1 002 Projected GCS_North_American_1983 Linear Unit: Meter (1.000000) NAD_1983_StatePlane_Maryland_FIPS_1900 <ProjectedCoordinateSystem xsi:type='typens:ProjectedCoordinateSystem' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:typens='http://www.esri.com/schemas/ArcGIS/10.6'><WKT>PROJCS["NAD_1983_StatePlane_Maryland_FIPS_1900",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",400000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-77.0],PARAMETER["Standard_Parallel_1",38.3],PARAMETER["Standard_Parallel_2",39.45],PARAMETER["Latitude_Of_Origin",37.66666666666666],UNIT["Meter",1.0],AUTHORITY["EPSG",26985]]</WKT><XOrigin>-36747100</XOrigin><YOrigin>-29091500</YOrigin><XYScale>121236910.21292362</XYScale><ZOrigin>-100000</ZOrigin><ZScale>10000</ZScale><MOrigin>-100000</MOrigin><MScale>10000</MScale><XYTolerance>0.001</XYTolerance><ZTolerance>0.001</ZTolerance><MTolerance>0.001</MTolerance><HighPrecision>true</HighPrecision><WKID>26985</WKID><LatestWKID>26985</LatestWKID></ProjectedCoordinateSystem> 32 FALSE None 1 TIFF TRUE continuous floating point -3.4028231e+38 1.0 The person responsible for the metadata information. National Geospatial-Intelligence Agency (NGA) l. Reston VA 20191 US 20100927 ArcGIS Metadata 1.0 National Geospatial-Intelligence Agency None Upon request from distributor. Data release caveats may apply Variable ERDAS Imagine format on DVD National Geospatial-Intelligence Agency None Upon request from distributor. Data release caveats may apply Variable Server=10.1.11.144; Service=5151; User=image; Version=SDE.DEFAULT Raster Dataset Bare_Earth_2008 2009-07 Science Applications International Corporation (SAIC) Science Applications International Corp. (SAIC) Chantilly, VA SDE raster digital data Reflective Surface DEM LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. Using a combination of laser rangefinding, GPS positioning and inertial measurement technologies; LIDAR instruments are able to make highly detailed Digital Elevation Models (DEMs) of the earth's terrain, man-made structures and vegetation. This data was collected at a resolution of 1 meter and includes reflective surface, last return, bare earth model and intensity data in separate data files. LIDAR data is used for 3D visualization, elevation based analysis and for feature extraction. n/a National Geospatial-Intelligence Agency US U.S. Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions (Federal Information Processing Standard (FIPS) 10-4): Washington, D.C., National Institute of Standards and Technology DC U.S. Department of Commerce, 1987, Codes for the Indentification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standards (FIPS) 5-2): Washington, D.C., National Institute of Standards and Technology. Washington City LIDAR Light Distancing And Ranging DEM Digital Elevation Model 1meter resolution elevation model Average ground sample distance 1m Reflective Surface Surface of first measurable laser pulses detected by sensor LIDAR DEM 1meter resolution elevation model Reflective Surface US DC Washington None. However, users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of it's limitations. No warranty expressed or implied is made by provider regarding the utility or the data on any other system, nor shall the act of distribution constitute any such warranty. US DOD Information Unclassified - distribution limited by Point of Contact Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.2.6.1500 true -77.125651 -76.903273 38.999587 38.787958 ground condition 2008-03-12 2008-12-23 Reflective surface data represents the DEM created by laser energy reflected from the first surface encountered by the laser pulse. Some energy may continue beyond this initial surface to be reflected by a subsequent surface as represented by the Last Return data. Intensity information is captured from the Reflective Surface pulse and indicates the relative energy returned to the sensor as compared to the energy transmitted. The Intensity image is not calibrated or normalized but indicates differences in energy absorption due to the the interaction of the surface materials with laser energy at the wavelength transmitted by the sensor. Bare earth model is created by identifying those returns that fall on the ground surface and interpolating a surface between these points. In this manner buildings and vegetation are removed from Bare Earth Model. This data set does not include bridges and overpasses in the Bare Earth model as the delineation point for these structures is not reliably discernable in the LiDAR data. 1 -77.125651 -76.903273 38.999587 38.787958 All IMG formatted image data are validated using commercial GIS software to ensure proper formatting and loading before delivery. This validation procedure ensures that data on delivery media is in correct physical format and is readable. LIDAR raster data is visually inspected for completeness to ensure that any gaps between flight lines or loss of signal represents less than 5% of required collection area. Areas of open water where loss of LIDAR signal is common are corrected to the best estimate of water level at time of collection. Areas of NODATA resulting from differences between required collection area and minimum bounding rectangle and/or areas of missing data are coded -999 to ensure compatibility between ESRI production software and ERDAS delivery format. LIDAR is self-illuminating and has minimal cloud penetration capability. Water vapor in steam plumes or particulates in smoke may cause reflection of LIDAR signals and loss of elevation information beneath these plumes. Glass structures and roofs may appear transparent to the LIDAR signal and therefore may not register on the reflective surface. Some asphalt formulations have been shown to absorb topographic LIDAR wavelength energy resulting in "pitting" of roof surfaces using this material. Horizontal accuracy of the source LIDAR data can be characterized by the rule of thumb of 1/2000th of flying height or roughly 0.5 meters for this collect. Spot checks in the field routinely are measured at 1/4000th of flying height but are not formally characterized. Estimated horizontal accuracy of extracted feature data. Informal assessments indicate that horizontal accuracy is better than 1 m based on comparisons with ortho imagery. Better than 1 m The vertical accuracy was tested following the National Standards for Spatial Data Accuracy. Washington DC: Based on a total of 45 control points, the average error between the bare earth LiDAR coverage and the control was 0.004m with a root mean square error (RMSE) of 0.107m. Washington DC Mall Area: The vertical accuracy was tested following the National Standards for Spatial Data Accuracy. Based on a total of 7 control points, the average error between the bare earth LiDAR coverage and the control was 0.034 m with a root mean square error (RMSE) of 0.095 m. Average error between Bare Earth LiDAR coverage and control 0.034 m The vertical accuracy was tested following the National Standards for Spatial Data Accuracy. Washington DC: Based on a total of 45 control points, the average error between the bare earth LiDAR coverage and the control was 0.004m with a root mean square error (RMSE) of 0.107m. Washington DC Mall Area: The vertical accuracy was tested following the National Standards for Spatial Data Accuracy. Based on a total of 7 control points, the average error between the bare earth LiDAR coverage and the control was 0.034 m with a root mean square error (RMSE) of 0.095 m. root mean square error (RMSE) 0.107 m Process Step: Production Narrative: Using a Leica Systems ALS50 Light Detection And Ranging (LiDAR) system, 259 flight lines of high density (submeter ground sample distance) data were collected over Washington DC (approximately 8,253 square kilometers). Two returns were recorded for each laser pulse along with an intensity value for each return. A total of nine missions were flown over a nine day period: October 31, 2008, November 10, 2008, November 11, 2008, December 6, 2008, December 7, 2008, December 8, 2008, December 13, 2008 and December 23, 2008. One airborne global positioning system (GPS) base station was used to support the LiDAR data acquisition: Woolpert placed base station (Woolpert_Manassas). In addition, 45 control points surveyed through static methods were tied into the Woolpert placed base station. Another 6 flight lines of high density (submeter ground sample distance) data were collected over Washington DC Mall area (approximately 43.5 square kilometers). Two returns were recorded for each laser pulse along with an intensity value for each return. A total of two missions were flown over a two day period: March 12, 2008 and March 21, 2008. Two airborne global positioning system (GPS) base stations were used to support the LiDAR data acquisition: GAI B (NGS point) and USNO (NGS CORS). In addition, twelve control points were surveyed through static methods tied into NGS control point GAI B and USNO. Airborne GPS data was differentially processed and integrated with the post processed IMU data to derive a smoothed best estimate of trajectory (SBET). The SBET was used to reduce the LiDAR slant range measurements to a raw reflective surface for each flight line. The coverage was classified to extract a bare earth digital elevation model (DEM) and separate last returns. Four layers of coverage were delivered in the ArcINFO ArcGrid binary format: reflective surface, bare-earth, last return and intensity. System Parameters: Washington DC: - Type of Scanner = Leica Systems ALS50 II - Data Acquisition Height = 6,500-feet AGL - Scanner Field of View = 44 degrees - Scan Frequency = 41.3 Hertz - Pulse Repetition Rate - 114.6 Kilohertz - Aircraft Speed = 140 KIAS - Swath Width = 1600-meters - Nominal Ground Sample Distance = 3.0-feet - Number of Returns Per Pulse = 2 (first and last) - Distance Between Flight Lines = 1165-meters Washington DC Mall Area: - Type of Scanner = Leica Systems ALS50 II - Data Acquisition Height = 4,000-feet AGL - Scanner Field of View = 40 degrees - Scan Frequency = 36.5 Hertz - Pulse Repetition Rate - 72.0 Kilohertz - Aircraft Speed = 126 KIAS - Swath Width = 887.6-feet - Nominal Ground Sample Distance = 3.0-feet - Number of Returns Per Pulse = 2 (first and last) - Distance Between Flight Lines = 621-feet System Calibration Procedure: The ALS50 calibration and system performance is verified on a periodic basis using Woolpert's calibration range. The calibration range consists of a large building and runway. The edges of the building and control points along the runway have been located using conventional survey methods. Inertial measurement unit (IMU) misalignment angles and horizontal accuracy are calculated by comparing the position of the building edges between opposing flight lines. The scanner scale factor and vertical accuracy is calculated through comparison of LiDAR data against control points along the runway. Field calibration is performed on all flight lines to refine the IMU misalignment angles. IMU misalignment angles are calculated from the relative displacement of features within the overlap region of adjacent (and opposing) flight lines. The raw LiDAR data is reduced using the refined misalignment angles. Post Processing Procedure: Airborne GPS is differentially processed using the GrafNAV V4.40 software by Waypoint Consulting of Calgary, Alberta, Canada. The PDOP and distance separation by day is as follows: March 12, 2008 (GAI B): Average PDOP = 1.7 Average Distance Separation: 40 km March 21, 2008 (USNO): Average PDOP = 1.5 Average Distance Separation: 15 km October 31, 2008: Average PDOP = 1.5 Average Distance Separation: 70 km November 10, 2008: Average PDOP = 1.5 Average Distance Separation: 45 km November 11, 2008: Average PDOP = 1.3 Average Distance Separation: 34 km December 6, 2008: Average PDOP = 1.4 Average Distance Separation: 30 km December 7, 2008: Average PDOP = 1.4 Average Distance Separation: 30 km December 8, 2008: Average PDOP = 1.5 Average Distance Separation: 95 km December 13, 2008_A: Average PDOP = 1.3 Average Distance Separation: 45 km December 13, 2008_B: Average PDOP = 1.3 Average Distance Separation: 50 km December 23, 2008: Average PDOP = 1.5 Average Distance Separation: 60 km IMU data is processed using the IPAS Pro software by Leica. The reflective surface is derived using the ALS Post Processor software by Leica Geosystems GIS & Mapping Division of Atlanta, Georgia. The classification and quality control (QC) of LiDAR data is carried out using a combination of Woolpert proprietary software and TerraScan software by Terrasolid Limited of Helinski, Finland. Data Consolidation and Review: Raw LiDAR data is delivered to contractor by collector. Four layers of coverage were delivered in the ArcINFO ArcGrid binary format: reflective surface, bare-earth, last return and intensity. These tiles are converted & merged into larger ESRI GRID files and reviewed for quality and consistency. Preliminary Bare Earth surface is reviewed and edited as required to remove or add features to bare earth surface as required by cartographic requirements 2009-07 Data Conversion: Merged tiles of ESRI GRID formatted data are converted to ERDAS Imagine image format. Areas coded as NODATA in ESRI GRID format are converted to -999 in ERDAS IMG format. IMG files are encoded with projection information for proper zone and datum as part of conversion process. Metadata is added. 2009-07 Metadata imported. W:\LIDAR_CITIES\DC_01\metadata\reflective_surface.xml Metadata imported. G:\Washington_DC_2009\reflective_surface_return.xml Metadata imported. Z:\Lidar2008_Pilot\DCReflectiveSurface_Project.img.xml Raw spatial elevation information 3000 LIDAR data collection LIDAR Woolpert Inc Washington DC: - Type of Scanner = Leica Systems ALS50 II - Data Acquisition Height = 6,500-feet AGL - Scanner Field of View = 44 degrees - Scan Frequency = 41.3 Hertz - Pulse Repetition Rate - 114.6 Kilohertz - Aircraft Speed = 140 KIAS - Swath Width = 1600-meters - Nominal Ground Sample Distance = 3.0-feet - Number of Returns Per Pulse = 2 (first and last) - Distance Between Flight Lines = 1165-meters Washington DC Mall Area: - Type of Scanner = Leica Systems ALS50 II - Data Acquisition Height = 4,000-feet AGL - Scanner Field of View = 40 degrees - Scan Frequency = 36.5 Hertz - Pulse Repetition Rate - 72.0 Kilohertz - Aircraft Speed = 126 KIAS - Swath Width = 887.6-feet - Nominal Ground Sample Distance = 3.0-feet - Number of Returns Per Pulse = 2 (first and last) - Distance Between Flight Lines = 621-feet ground condition 2008-03-12 2008-12-23 Collection System Calibration Woolpert LLP The ALS50 calibration and system performance is verified on a periodic basis using Woolpert's calibration range. The calibration range consists of a large building and runway. The edges of the building and control points along the runway have been located using conventional survey methods. Inertial measurement unit (IMU) misalignment angles and horizontal accuracy are calculated by comparing the position of the building edges between opposing flight lines. The scanner scale factor and vertical accuracy is calculated through comparison of LiDAR data against control points along the runway. Field calibration is performed on all flight lines to refine the IMU misalignment angles. IMU misalignment angles are calculated from the relative displacement of features within the overlap region of adjacent (and opposing) flight lines. The raw LiDAR data is reduced using the refined misalignment angles. 2008-03-12 2008-12-23 3 23485 1.000000 19263 1.000000 1 1 0 389115.783170 124475.365051 389115.783170 147960.365051 408378.783170 147960.365051 408378.783170 124475.365051 398747.283170 136217.865051 dataset EPSG 4.5(3.0.1) Band_1 130.759995 -8.130000 32