Connecticut River Basin, Vermont 2016 QL2 LiDAR Project

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: Quantum Spatial

Publication_Date: 20171013

Title: Connecticut River Basin, Vermont 2016 QL2 LiDAR Project

Geospatial_Data_Presentation_Form: Lidar point cloud

Description:

Abstract:

Product: This lidar data set includes unclassified swath LAS 1.4 files, classified LAS 1.4 files, breaklines, digital elevation models (DEMs), digital surface models (DSMs), intensity imagery, and contours. Geographic Extent: Several counties within the Connecticut River Basin in northeastern Vermont, covering approximately 2,858 square miles. Dataset Description: The Connecticut River Basin, Vermont 2016 QL2 Lidar project called for the planning, acquisition, processing, and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.7 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011) State Plane Vermont, meters and vertical datum of NAVD88 (Geoid 12B), meters. Lidar data was delivered as flightline-extent unclassified LAS swaths, as processed Classified LAS 1.4 files formatted to 4,149 individual 1,400-meter x 1,400-meter tiles, as tiled intensity imagery, as tiled bare earth DEMs, and as tiled first-return DSMs; all tiled to the same 1,400-meter x 1,400-meter schema. Continuous combination hydro-flattened/hydro-enforced breaklines were produced in Esri file geodatabase format. Tiled 1-foot contours were created in Esri file geodatabase format. Mosaics of the 0.7-meter hydro-flattened DEMs, 0.7-meter hydro-enforced DEMs, and 0.7-meter first-return DSM data were produced in ERDAS .IMG format and clipped to county boundaries. Ground Conditions: Lidar was collected in Fall 2016, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Quantum Spatial, Inc. established a total of 57 ground control points that were used to calibrate the lidar to known ground locations established throughout the Connecticut River Basin, VT project area. An additional 149 independent accuracy checkpoints, 84 in Bare Earth and Urban landcovers (84 NVA points), 65 in Forested, Shrubs, and Tall Weeds categories (65 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

Purpose:

This high resolution lidar data will support the state of Vermont and local governments in their efforts regarding activities in the identified area. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create intensity images, breaklines, and raster DEMs. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened digital elevation models (DEMs) with a 0.7-meter cell size. These raw lidar point cloud data were used to create classified lidar LAS files, intensity images, 3D breaklines, hydro-flattened and hydro-enforced DEMs, digital surface models, and contours as necessary.

Supplemental_Information:

USGS Contract No. G16PC00016 CONTRACTOR: Quantum Spatial, Inc. Lidar data were acquired by Quantum Spatial, Inc. All follow-on processing was completed by the prime contractor.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20161101

Ending_Date: 20161119

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: -72.8824076971063

East_Bounding_Coordinate: -71.4546187846429

North_Bounding_Coordinate: 45.0186791332973

South_Bounding_Coordinate: 43.1043648062303

Keywords:

Theme:

Theme_Keyword_Thesaurus: None

Theme_Keyword: Model

Theme_Keyword: LAS Point Cloud

Theme_Keyword: Remote Sensing

Theme_Keyword: Elevation Data

Theme_Keyword: Lidar

Theme_Keyword: Hydrology

Theme_Keyword: Breaklines

Theme_Keyword: Raster

Theme_Keyword: DEM

Theme_Keyword: DSM

Theme_Keyword: Contours

Place:

Place_Keyword_Thesaurus: None

Place_Keyword: Vermont

Place_Keyword: Bennington County

Place_Keyword: Caledonia County

Place_Keyword: Essex County

Place_Keyword: Orange County

Place_Keyword: Orleans County

Place_Keyword: Washington County

Place_Keyword: Windham County

Place_Keyword: Windsor County

Access_Constraints: No restrictions apply to this data.

Use_Constraints:

None. However, users should be aware that temporal changes may have occurred since this dataset was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of its limitations. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.

Data_Quality_Information:

Logical_Consistency_Report: Data cover the entire area specified for this project.

Completeness_Report:

All files are inspected to ensure that they conform to the specified file naming conventions, all files load in their correct geographic position, all files conform to the project specifications for file standard and content.

Positional_Accuracy:

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

The project specifications require that only Non-Vegetated Vertical Accuracy (NVA) be computed for raw lidar point cloud swath files. The required accuracy (ACCz) is: 19.6 cm at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 10 cm in the "bare earth" and "urban" land cover classes. The NVA was tested with 82 of 84 checkpoints located in bare earth and urban (non-vegetated) areas; points BE51 and UA27 were excluded as they fell outside the AOI. These check points were not used in the calibration or post processing of the lidar point cloud data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. Elevations from the unclassified lidar surface were measured for the x,y location of each check point. Elevations interpolated from the lidar surface were then compared to the elevation values of the surveyed control points. AccuracyZ has been tested to meet 19.6 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines. The project specifications require the accuracy (ACCz) of the derived DEM be calculated and reported in two ways: 1. The required NVA is: 19.6 cm at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 10 cm in the "bare earth" and "urban" land cover classes. This is a required accuracy. The NVA was tested with 82 of 84 checkpoints located in bare earth and urban (non-vegetated) areas; points BE51 and UA27 were excluded as they fell outside the AOI. 2. Vegetated Vertical Accuracy (VVA): VVA shall be reported for "forested", "shrubs", and "tall weeds" land cover classes. The target VVA is: 29.4 cm at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for Lidar Data, i.e., based on the 95th percentile error in all vegetated land cover classes combined. This is a target accuracy. The VVA was tested with 64 of 65 checkpoints located in forested, shrubs, and tall weeds (vegetated) areas; point FO24 was excluded as it was a bad point. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. AccuracyZ has been tested to meet 19.6 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.

Quantitative_Vertical_Positional_Accuracy_Assessment:

Vertical_Positional_Accuracy_Value: 0.088

Vertical_Positional_Accuracy_Explanation:

Tested 0.088 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the raw lidar point cloud swath files was calculated against TINs derived from the final calibrated and controlled swath data using 82 independent checkpoints located in Bare Earth and Urban land cover classes.

Quantitative_Vertical_Positional_Accuracy_Assessment:

Vertical_Positional_Accuracy_Value: 0.100

Vertical_Positional_Accuracy_Explanation:

Tested 0.100 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the DEM was calculated using 82 independent checkpoints located in the Bare Earth and Urban land cover categories.

Quantitative_Vertical_Positional_Accuracy_Assessment:

Vertical_Positional_Accuracy_Value: 0.187

Vertical_Positional_Accuracy_Explanation:

Tested 0.187 meters VVA was calculated using 64 checkpoints located in the Forested, Shrubs, and Tall Weeds land cover categories at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for Lidar Data. Tested against the DEM.

Lineage:

Process_Step:

Process_Description:

Raw Data and Boresight Processing: The boresight for each lift was done individually as the solution may change slightly from lift to lift. The following steps describe the Raw Data Processing and Boresight process: 1) Technicians processed the raw data to LAS format flight lines using the final GPS/IMU solution. This LAS data set was used as source data for boresight. 2) Technicians first used Quantum Spatial, Inc. proprietary and commercial software to calculate initial boresight adjustment angles based on sample areas selected in the lift. These areas cover calibration flight lines collected in the lift, cross tie and production flight lines. These areas are well distributed in the lift coverage and cover multiple terrain types that are necessary for boresight angle calculation. The technician then analyzed the results and made any necessary additional adjustment until it is acceptable for the selected areas. 3) Once the boresight angle calculation was completed for the selected areas, the adjusted settings were applied to all of the flight lines of the lift and checked for consistency. The technicians utilized commercial and proprietary software packages to analyze how well flight line overlaps match for the entire lift and adjusted as necessary until the results met the project specifications. 4) Once all lifts were completed with individual boresight adjustment, the technicians checked and corrected the vertical misalignment of all flight lines and also the matching between data and ground truth. The relative accuracy was less than or equal to 7 cm RMSEz within individual swaths and less than or equal to 10 cm RMSEz or within swath overlap (between adjacent swaths). 5) The technicians ran a final vertical accuracy check of the boresighted flight lines against the surveyed check points after the z correction to ensure the requirement of NVA = 19.6 cm 95% Confidence Level (Required Accuracy) was met.

Process_Date: 2017

Process_Step:

Process_Description:

LAS Point Classification: The point classification is performed as described below. The bare earth surface is then manually reviewed to ensure correct classification on the Class 2 (Ground) points. After the bare-earth surface is finalized, it is then used to generate all hydro-breaklines through heads-up digitization. All ground (ASPRS Class 2) lidar data inside of the Lake Pond and Double Line Drain hydro-flattened breaklines were then classified to Water (ASPRS Class 9) using TerraScan macro functionality. A buffer of 1 meter was also used around each hydro-flattened feature to classify these ground (ASPRS Class 2) points to Ignored ground (ASPRS Class 10). All Lake Pond Island and Double Line Drain Island features were checked to ensure that the ground (ASPRS Class 2) points were reclassified to the correct classification after the automated classification was completed. All bridge decks were classified to Class 17. All overlap data was processed through automated functionality provided by TerraScan to classify the overlapping flight line data to approved classes by USGS. The overlap data was classified using standard LAS overlap bit. These classes were created through automated processes only and were not verified for classification accuracy. Due to software limitations within TerraScan, these classes were used to trip the withheld bit within various software packages. These processes were reviewed and accepted by USGS through numerous conference calls and pilot study areas. All data was manually reviewed and any remaining artifacts removed using functionality provided by TerraScan and TerraModeler. Global Mapper us used as a final check of the bare earth dataset. GeoCue was then used to create the deliverable industry-standard LAS files for both the All Point Cloud Data and the Bare Earth. Quantum Spatial, Inc. proprietary software was used to perform final statistical analysis of the classes in the LAS files, on a per tile level to verify final classification metrics and full LAS header information.

Process_Date: 2017

Process_Step:

Process_Description:

Hydro-Flattened/Hydro-Enforced Breakline Processing: Class 2 (ground) lidar points was used to create a bare earth surface model. The surface model was then used to heads-up digitize 2D breaklines of inland streams and rivers with a 100-foot nominal width and inland ponds and lakes of 2 acres or greater surface area. Elevation values were assigned to all Inland Ponds and Lakes, Inland Pond and Lake Islands, Inland Stream and River Islands, using TerraModeler functionality. Elevation values were assigned to all inland streams and rivers using Quantum Spatial, Inc. proprietary software. All Ground (ASPRS Class 2) lidar data inside of the collected inland breaklines were then classified to Water (ASPRS Class 9) using TerraScan macro functionality. A buffer of 3 feet was also used around each hydro-flattened feature. These points were moved from ground (ASPRS Class 2) to Ignored Ground (ASPRS Class 10). Hydro enforcement was also a requirement of this task order. This was accomplished by connecting any collected hydro feature that met the collection parameters. Any ground (ASPRS Class 2) LiDAR data inside of this collected feature was then moved to Class 13, a mutually agreed upon class between USGS and Quantum Spatial. The breakline files were then translated to Esri file geodatabase format using Esri conversion tools. Breaklines are reviewed against lidar intensity imagery to verify completeness of capture. All breaklines are then compared to TINs (triangular irregular networks) created from ground only points prior to water classification. The horizontal placement of breaklines is compared to terrain features and the breakline elevations are compared to lidar elevations to ensure all breaklines match the lidar within acceptable tolerances. Some deviation is expected between breakline and lidar elevations due to monotonicity, connectivity, and flattening rules that are enforced on the breaklines. Once completeness, horizontal placement, and vertical variance is reviewed, all breaklines are reviewed for topological consistency and data integrity using a combination of Esri Data Reviewer tools and proprietary tools.

Process_Date: 2017

Process_Step:

Process_Description:

Hydro-Flattened Raster DEM Processing: Class 2 (Ground) LiDAR points in conjunction with the hydro-breaklines were used to create a 0.7-meter hydro-flattened raster DEM. Using automated scripting routines within ArcMap, an ERDAS Imagine .IMG file was created for each tile. Each surface is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface.

Process_Date: 2017

Process_Step:

Process_Description:

Hydro-Enforced Raster DEM Processing: Class 2 (Ground) LiDAR in conjunction with the hydro-breaklines and any collected enforcement lines were used to create a 0.7-meter hydro-enforced raster DEM. Using automated scripting routines within ArcMap, an ERDAS Imagine .IMG file was created for each tile. Each surface is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface.

Process_Date: 2017

Process_Step:

Process_Description:

First Return DSM Processing: First return and non-noise LiDAR was used to create a 0.7-meter raster DSM. Using automated scripting routines within ArcMap, an ERDAS Imagine .IMG file was created for each tile. Each surface is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface.

Process_Date: 2017

Process_Step:

Process_Description:

Intensity Image Processing: GeoCue software was used to create the deliverable intensity images. All overlap classes were ignored during this process. This helps to ensure a more aesthetically pleasing image. The GeoCue software was then used to verify full project coverage as well. ERDAS Imagine .IMG files were then provided as the deliverable for this dataset requirement.

Process_Date: 2017

Process_Step:

Process_Description:

Contour Processing: Using automated scripting routines within ArcMap, a terrain surface was created using the ground (ASPRS Class 2) LiDAR data as well as the hydro-breaklines. This surface was then used to generate the final 1-foot contour dataset in Esri file geodatabase format.

Process_Date: 2017

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Point

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: 4400

Transverse_Mercator:

Scale_Factor_at_Central_Meridian: 0.999964285714286

Longitude_of_Central_Meridian: -72.5

Latitude_of_Projection_Origin: 42.5

False_Easting: 500000.0

False_Northing: 0.0

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method: coordinate pair

Coordinate_Representation:

Abscissa_Resolution: 0.01

Ordinate_Resolution: 0.01

Planar_Distance_Units: meter

Geodetic_Model:

Horizontal_Datum_Name: North American Datum of 1983 (2011)

Ellipsoid_Name: Geodetic Reference System 80

Semi-major_Axis: 6378137.0

Denominator_of_Flattening_Ratio: 298.257222101

Vertical_Coordinate_System_Definition:

Altitude_System_Definition:

Altitude_Datum_Name: North American Vertical Datum of 1988 (Geoid 12B)

Altitude_Resolution: 0.01

Altitude_Distance_Units: meters

Altitude_Encoding_Method:

Explicit elevation coordinate included with horizontal coordinates

Metadata_Reference_Information:

Metadata_Date: 20171013

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: Quantum Spatial

Contact_Address:

Address_Type: mailing and physical

Address: 523 Wellington Way

City: Lexington

State_or_Province: KY

Postal_Code: 40503

Country: USA

Contact_Voice_Telephone: 859-277-8700

Contact_Facsimile_Telephone: 859-277-8901

Hours_of_Service: Monday through Friday 8:00 AM to 5:00 PM (Eastern Time)

Contact_Instructions:

If unable to reach the contact by telephone, please send an email. You should get a response within 24 hours.

Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Access_Constraints: None.

Metadata_Use_Constraints: None.

Metadata_Security_Information:

Metadata_Security_Classification_System: None.

Metadata_Security_Classification: Unclassified

Metadata_Security_Handling_Description: NONE