Salt Lake City, Utah, 2006, 1/9-Arc Second National Elevation Dataset

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: U.S. Geological Survey

Publication_Date: 2008

Title:

Salt Lake City, Utah, 2006, 1/9-Arc Second National Elevation Dataset

Geospatial_Data_Presentation_Form: SDE raster digital data

Series_Information:

Series_Name: National Elevation Data (NED)

Issue_Identification: 0.1

Publication_Information:

Publication_Place: Sioux Falls, SD

Publisher: U.S. Geological Survey

Online_Linkage: <http://nationalmap.usgs.gov>

Description:

Abstract:

None provided.
Information in quotation marks is taken from the original data source's metadata.

Purpose: None provided.

Supplemental_Information:

The metadata was created with information extracted from Horizon, Inc.'s Acquisition, Processing and Quality Control, and the State of Utah, Scope of Work documents received with the original data.
The data obtained through The National Map Seamless Server is considered to be the "best available" data from USGS. Historical data and other data may be obtained by contacting Customer Services, Earth Resources Observation & Science Center at 1-800-252-4547. Information in quotation marks, initial processing steps, accuracy reports, and source information is taken directly from the original metadata.

QUADNAME	RESOLUTION	ULLAT	ULLON	LRLAT	LRLON	HDATUM	ZMIN	ZMAX	ZMEAN	ZSIGMA	PMETHOD	QUADDATE
	19	0	0	0	0	0	0	0	0	0	7	20090920

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 20061116

Beginning_Time: unknown

Ending_Date: 20061207

Ending_Time: unknown

Currentness_Reference: ground condition

Status:

Progress: Complete

Maintenance_and_Update_Frequency: None planned

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate:-111.837283949489

East_Bounding_Coordinate:-111.819413579118

North_Bounding_Coordinate:40.5336728395125

South_Bounding_Coordinate:40.5270061728459

Data_Quality_Information:

Logical_Consistency_Report: N/A

Completeness_Report:

GPS Data Collection
A GPS receiver was in constant operation over a National Geodetic Survey control point during flight acquisition. The base station identification and location are listed in the following table. Base station information is also included in the Appendix.
Station LocationLO0622 40 37 05.78236111 59 47.19312
GPS base station
GPS Data Processing
All GPS phase data was post processed with continuous kinematic survey techniques using "On the Fly" (OTF) integer ambiguity resolution. The GPS data was processed with forward and reverse processing algorithms. The results from each process, using the data collected at the airport, were combined to yield a single fixed integer phase differential solution of the aircraft trajectory. Plots of altitude and the forward and reverse GPS solution residuals are included in the Appendix. The differences between the forward to reverse solution within the project area were within project specifications (<10cm) in both the horizontal and vertical components, indicating a valid and accurate solution.
IMU Data Processing
An IMU was used to record precise changes in position and orientation of the LIDAR scanner at a rate of 200 Hz. All IMU data was processed post flight with a filter to integrate inertial measurements and precise phase differential GPS positions. The resulting solution contains geodetic position, omega, phi, kappa, and time for subsequent merging with the laser ranging information.
LiDAR Data Processing
LIDAR Data Preprocess - Flight Line Data Acquisition/Quality Control CheckLiDAR data and the IMU files were processed together using LIDAR processing software. The data set for each flight line was checked for project area coverage, data gaps between overlapping flight lines, and tension/compression areas (areas where data points are more or less dense than the average project specified post spacing). Based on this check it appears the entire project area is covered without gaps.
Boresighting ProcessPre-processing of LiDAR corrects for rotational, atmospheric, and elevation differences that are inherent to LiDAR data sets. This process is called boresighting. LiDAR data was collected for bi- and cross-directional flight lines over the project area. Using an iterative process that involves analyzing raster difference calculations the Omega, Phi, Kappa angle corrections of the LiDAR instrument were determined. The corrections were applied to the LiDAR data set for the project area.
Vertical Accuracy CheckExtensive comparisons were made of vertical and horizontal positional differences between points common to two or more LiDAR flight lines. This was done for the airport bore-sight testing area and the project area. All flight lines (airport and project) were within project specifications for vertical accuracy.
LiDAR Intensity CheckAn intensity raster for each flight line was generated. The raster was checked and verified that intensity was recorded for each LiDAR point.
Project Coordinate SystemLiDAR preprocessing software outputs data to its corresponding UTM zone in meters and a GRS80 ellipsoidal height. LiDAR data was transformed to a project coordinate system of NAD83 NAVD88 Meters UTM zone 12 Geoid 03 .
Vertical Bias CorrectionLiDAR has a consistent vertical offset. LiDAR ground points were compared to independently surveyed and positioned ground control points in the project area. Based on the results of these comparisons, the LiDAR data was vertically biased down to the ground.
Project Ground Control CheckComparisons between on-site ground survey control points and LiDAR data yielded the following results:
1 Meter AreaVertical Accuracy (RMSE) 0.041Standard Deviation 0.043Mean Difference -0.006Number of Points 10
LiDAR Data Surfacing Process
Raw LiDAR Data SetLiDAR data in overlap areas of project flight lines was removed and data from all swaths was merged into a single data set. The data set was trimmed to the digital project boundary including an additional buffer zone (buffer zone assures adequate contour generation from the DEM). Resulting data set is the Raw LiDAR data. The Raw LiDAR data set was processed through a minimum block mean algorithm and points were classified as either bare earth or non-bare earth. User developed "macros" that factor mean terrain angle and height from the ground, were used to determine bare earth point classification.
LiDAR Surfacing Process
The surfacing process is a 2D-edit procedure that ensures the accuracy of the automated feature classification. Editors used a combination of imagery, intensity of the LiDAR reflection and tin-editing software to assess points. The resulting data set is 2D Surfaced Bare Earth. The LiDAR data is filtered using a quadric error metric to remove redundant points. This method leaves points where there is a change in the slope of surfaces (road ditches) and eliminates points from evenly sloped terrain (flat field) where the points do not affect the TIN LiDAR data. The resulting data set is 2D Surfaced/Filtered Bare Earth.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report: N/A

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report: N/A

Lineage:

Process_Step:

Process_Description:

STEP 1: RAW IMAGE DOWNLOADThe raw image download is accomplished in the field with on a portable workstation. This enables a quick look at image quality and coverage.
STEP 2: DIFFERENTIAL GPS AND IMU PROCESSINGUsing the Applanix POSgps software package the GPS data is differentially processed against a base station. After the differential GPS solution has been checked and verified the Applanix POSproc program is used to compute an integrated GPS/IMU navigation solution at one-second intervals.
STEP 3: GEOREFERENCE OF RAW L0 IMAGERYUsing the GPS/IMU trajectory computed by the Applanix POSproc software and the camera calibration, software computes a full x,y,z, omega,phi,kappa exterior orientation of each scan line.
STEP 4: EPIPOLAR RESAMPLE AND CREATION OF L1 IMAGERYUsing the orientation data file produced in step 3 the L0 imagery is resampled. The resampling removes most aircraft motion and provides epipolar geometry for stereo viewing, automated aerotriangulation and automated DEM extraction.
STEP 5: AEROTRIANGULATIONThe Level 1 epipolar-resampled and georeferenced imagery usually will provide a pixel's true ground location to within a few pixels without any additional processing. To improve accuracy, a fully automatic aerotriangulation process can be performed to minimize the residual errors in the GPS/IMU derived exterior orientations. The aerotriangulation also allows the introduction of ground control and checkpoints to ensure the accuracy specifications are achieved. Automated aerotriangulation of ADS40 imagery is performed. Because the ADS sensor provides 100% stereo overlap vs. 60% for conventional frame photography the process results in orientation/positional accuracies to the sub-pixel level in less time than required for the same process with film imagery but requires significant computer processing resources. Aerotriangulation is typically performed using three bands; the backward viewing pan band, the green band at nadir view and the green forward viewing band. The other bands are adjusted based on their relationship to the bands used in the adjustment.
STEP 6: DEM EXTRACTIONA digital elevation model (DEM) is required for orthophoto production. While for some projects an existing DEM is appropriate there will inevitably be areas for which new photography and an older DEM will not match. Using L1 imagery a fully automated DEM extraction is possible. The software generates DTM points by measuring X-shifts in the rectified level-1 stereo image pairs. DTM grid files are created for each flight line and with the accuracy of the resulting DTM represented by a 90% probability circular error (CE) and linear error (LE). The edited DTM data is used to rectify the Level-2 ortho strips.
STEP 7: ORTHOPHOTO PRODUCTIONOrtho-rectification is performed for the entire image strip at once, which is more efficient that managing many frame images. Resampling the original L0 image with the refined orientation produced by aerotriangulation and the requisite DEM. After the creation of the Orthophotos, the images are run through a proprietary program that adjusts the gradient across each image to improve the tone balance of the images. This program also breaks the ADS40 orthophoto strip into more manageable overlapping tiles. We import these orthophotos into ORTHOVISTA where radiometric and color corrections are made on multiple flight lines at once. Upon completion the images are imported into horizons' proprietary image software. Images are mosaicked together using a "path of least resistance" algorithm to generate seam lines. When the initial database is generated, the Ortho-Technician overlays the DEM/DTM to check for correct orientations and obvious image errors.
The Ortho-Technician then systematically goes through the database looking at every seam. If a seam is noticeable and can be lessened or be made "invisible" by moving the seam; the Technician will evaluate the overlapping image tiles to choose the "best fit" and mosaic the "new" seam line into the image database. Once all of the seam lines have been checked and corrected ortho tiles are then clipped from the image database and put through a thorough Q/C process. Any discrepancies found are marked and corrected inside of the image database. Once this process is complete the final ortho tiles are clipped from the database and written to media for delivery.

Process_Date: 2006

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Gene Ensor, EIT

Contact_Organization: Horizons Inc.

Contact_Position: Project Manager

Contact_Address:

Address_Type: unknown

Address: unknown

City: unknown

State_or_Province: unknown

Postal_Code: unknown

Country: USA

Contact_Voice_Telephone: 605/343-0280

Contact_TDD/TTY_Telephone: N/A

Contact_Facsimile_Telephone: none

Contact_Electronic_Mail_Address: Gene.Ensore@horizonsinc.com

Process_Step:

Process_Description:

LiDAR Production
1) PRE-PROCESSING STAGELiDAR, GPS and IMU data are processed together using LiDAR processing software. The LiDAR data set for each flight line is checked for project area coverage and LiDAR post spacing is checked to ensure it meets project specifications. The LiDAR collected at the calibration area is used to correct the rotational, atmospheric, and vertical elevation differences that are inherent to LiDAR data. Intensity rasters are generated to verify that intensity was recorded for each LiDAR point. LiDAR data is transformed to the specified project coordinate system. By utilizing the ground survey data collected at the calibration site and project area, the LiDAR data is vertically biased to the ground. Comparisons between the biased LiDAR data and ground survey data within the project area are evaluated and a final RMSE value is generated to ensure the data meets project specifications. LiDAR data in overlap areas of project flight lines is removed and data from all swaths is merged into a single data set. The data set is trimmed to the digital project boundary including an additional buffer zone which is typically about 50 feet (buffer zone assures adequate contour generation from the DEM). The resulting data set is referred to as the raw LiDAR data.
2) SURFACING STAGEThe raw LIDAR data is processed through a minimum block mean algorithm and points are classified as either bare earth or non-bare earth. User developed "macros" that factor mean terrain angle and height from the ground are used to determine bare earth point classification. The next phase of the surfacing process is a 2D edit procedure that ensures the accuracy of the automated feature classification. Editors use a combination of imagery, intensity of the LiDAR reflection and tin-editing software to assess points and add breaklines where necessary to define the terrain. The LiDAR data is filtered, as necessary, using a quadric error metric to remove redundant points. This method leaves points where there is a change in the slope of surfaces (road ditches) and eliminates points from evenly sloped terrain (flat field) where the points do not affect the surface. The resulting data set is referred to as "bare-earth LiDAR"
3) BREAKLINE COLLECTIONBreaklines will be collected on major break features in the topography.
4) CREATION OF THE DEMThe bare-earth LiDAR surface will be triangulated to form an evenly spaced DEM.

Process_Date: 2006

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Gene Ensor, EIT

Contact_Organization: Horizons Inc.

Contact_Position: Project Manager

Contact_Address:

Address_Type: unknown

Address: unknown

City: unknown

State_or_Province: unknown

Postal_Code: unknown

Country: USA

Contact_Voice_Telephone: 605/343-0280

Contact_TDD/TTY_Telephone: N/A

Contact_Facsimile_Telephone: none

Contact_Electronic_Mail_Address: Gene.Ensore@horizonsinc.com

Process_Step:

Process_Description:

The LiDAR digital elevation models of the Salt Lake City, Utah study area were mosaicked into one large area and projected into NAD83 Geographic projection using ESRI software. A footprint was generated and clipped to the data extent. The quality control was performed by reviewing the shaded-relief dataset for irregularities and doing comparisons of the data with the 1/3-arc-second National Elevation Dataset and Google Earth.
This metadata was created to included USGS FGDC-compliant information and USGS EROS processing steps for display through The National Map Seamless Server at <http://nationalmap.usgs.gov>. Project level metadata are available in several formats: HTML, TEXT, XML, FAQ and SGML.

Process_Date: 2008

Process_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: U.S. Geological Survey

Contact_Position: Customer Service Representative

Contact_Address:

Address_Type: mailing and physical address

Address: USGS Earth Resources Observation & Science Center

Address: 47914 252nd Street

City: Sioux Falls

State_or_Province: SD

Postal_Code: 57198-0001

Country: USA

Contact_Voice_Telephone: 605-594-6151

Contact_Voice_Telephone: 1-800-252-4547

Contact_TDD/TTY_Telephone: 605-594-6933

Contact_Facsimile_Telephone: 605-594-6589

Contact_Electronic_Mail_Address: custserv@usgs.gov

Hours_of_Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)

Contact_Instructions:

The USGS point of contact is for questions relating only to the data display and download from this web site. For questions regarding data content and quality, refer to original processor. (See Source_Information above.)

Cloud_Cover: 0

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Raster_Object_Information:

Raster_Object_Type: Pixel

Row_Count: 216

Column_Count: 579

Vertical_Count: 1

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution: 0.00001

Longitude_Resolution: 0.00001

Geographic_Coordinate_Units: Decimal degrees

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

Vertical_Coordinate_System_Definition:

Altitude_System_Definition:

Altitude_Datum_Name: North American Vertical Datum of 1988

Altitude_Resolution: 1.000000

Altitude_Distance_Units: meters

Altitude_Encoding_Method:

Explicit elevation coordinate included with horizontal coordinates

Entity_and_Attribute_Information:

Overview_Description:

Entity_and_Attribute_Overview:

All LiDAR datasets RMSE 1m RMSE 18.5cm in Bare Earth - NSSDA 95% of 36cm(2m, 1.4m & 1.0m DEM) NSSDA 95% of 1.7m RMSE 37 cm in Vegetation - NSSDA 95% of 73cm

Entity_and_Attribute_Detail_Citation: N/A

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: U.S. Geological Survey

Contact_Position: Customer Services Representative

Contact_Address:

Address_Type: mailing and physical address

Address: USGS Earth Resources Observation & Science Center

Address: 47914 252nd Street

City: Sioux Falls

State_or_Province: SD

Postal_Code: 57198-0001

Country: USA

Contact_Voice_Telephone: 605/594-6151

Contact_Voice_Telephone: 1-800-252-4547

Contact_TDD/TTY_Telephone: 605/594-6933

Contact_Facsimile_Telephone: 605/594-6589

Contact_Electronic_Mail_Address: custserv@usgs.gov

Hours_of_Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)

Contact_Instructions:

The USGS point of contact is for questions relating only to the data display and download from this web site. For questions regarding data content and quality, refer to the original processor.

Resource_Description: Downloadable Data

Distribution_Liability:

Although these data have been processed successfully on a computer system at the USGS, no warranty expressed or implied is made by the USGS regarding the use of the data on any other system, nor does the act of distribution constitute any such warranty. Data may have been compiled from various outside sources. Spatial information may not meet National Map Accuracy Standards. This information may be updated without notification. The USGS shall not be liable for any activity involving these data, installation, fitness of the data for a particular purpose, its use, or analyses results.

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: ARCG

Format_Version_Number: ArcGIS 9.1

Format_Specification: Raster

Transfer_Size: 0.001

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name: <http://nationalmap.usgs.gov>

Access_Instructions:

The URL, <http://nationalmap.usgs.gov>, provides a map interface that allows for data downloads within a customer defined area of interest. Zoom tools are available that can be used to investigate areas of interest on the map interface. The download tool allows the customer to capture layers from the map, utilizing The National Map Seamless Server process for downloading. A request summary page is then generated with the download layers listed. By clicking the "download" button on the summary page, a zipped file will be generated that can be saved on the customer's computer. The file can then be unzipped and imported into various user software applications.

Online_Computer_and_Operating_System: Not available for dissemination

Fees: None

Ordering_Instructions: Downloadable data.

Turnaround: Variable

Custom_Order_Process: None

Technical_Prerequisites:

ESRI ArcMap Suite and/or Arc/Info software or equivalent GIS processing software and supporting operating systems.

Available_Time_Period:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 2008

Ending_Date: unknown

Metadata_Reference_Information:

Metadata_Date: 20080918

Metadata_Contact:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: U.S. Geological Survey

Contact_Position: Customer Services Representative

Contact_Address:

Address_Type: mailing and physical address

Address: USGS Earth Resources Observation & Science Center

Address: 47914 252nd Street

City: Sioux Falls

State_or_Province: SD

Postal_Code: 57198-0001

Country: USA

Contact_Voice_Telephone: 605/594-6151

Contact_Voice_Telephone: 1-800-252-4547

Contact_TDD/TTY_Telephone: 605/594-6933

Contact_Facsimile_Telephone: 605/594-6589

Contact_Electronic_Mail_Address: custserv@usgs.gov

Hours_of_Service: 0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)

Contact_Instructions:

The above is the contact information for the USGS Earth Resources Observation and Science Center in Sioux Falls, SD. This is the digital data storage and distribution center for the USGS. Metadata information can also be obtained through online services using The National Map Viewer, at <http://nationalmap.usgs.gov>.

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time

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

Metadata_Extensions:

Online_Linkage: <http://www.esri.com/metadata/esriprof80.html>

Profile_Name: ESRI Metadata Profile