LiDAR Quality Assessment Report

Transcription

1 LiDAR Quality Assessment Report The USGS National Geospatial Technical Operations Center, Data Operations Branch is responsible for conducting reviews of all Light Detection and Ranging (LiDAR) pointcloud data and derived products delivered by a data supplier before it is approved for inclusion in the National Elevation Dataset and the Center for LiDAR Information Coordination and Knowledge. The USGS recognizes the complexity of LiDAR collection and processing performed by the data suppliers and has developed this Quality Assessment (QA) procedure to accommodate USGS collection and processing specifications with flexibility. The goal of this process is to assure LiDAR data are of sufficient quality for database population and scientific analysis. Concerns regarding the assessment of these data should be directed to the Chief, Data Operations Branch, 1400 Independence Road, Rolla, Missouri or NGTOCoperations@usgs.gov. Materials Received: 2/20/2013 Project ID: IL_RiverFP_2009 Project Alias(es): MISSISSIPPI RIVER / ILLINOIS WATER... Project Type: Partnership Project Description: This contract produced modified FEMA grade LIDAR as an extension of the existing work with the State of Iowa and USGS. This processed LIDAR has the potential to support a two foot contour. The deliverables include bareearth processed LIDAR data for bluff to bluff coverage of the River valleys. This data will primarily be used for watershed modeling, storm water planning, floodplain determination, and structure design and estimation. Additional uses for this data by other agencies include roadway design, wetland restoration, and conservation practice design, placement, and estimating. The LIDAR acquisition was scheduled to occur during the fall or early winter of Leaf-off conditions were required, and minimal snow coverage would be allowed (not to exceed a dusting of one inch or less). Due to extreme weather conditions through the duration of the task order, the original schedule was extended into 2011 in order to acquire LiDAR data within specification. As a result of the extended schedule, temporal changes may affect LiDAR data continuity. 1 QA Form V1.1 24AUG11

2 Task Orders 18 & 21 were combined to take advantage of an acquisition opportunity, as the counties were overlapping the flood plain. The LiDAR data was flown and calibrated as one contiguous project area, and survey data was collected to support the area as a single entity. Year of Collection: 12/16/2009 to 12/28/2011 Lot 1 of 1 lots. Project Extent: Project Extent image? 2 QA Form V1.1 24AUG11

3 Project Tiling Scheme: 3 QA Form V1.1 24AUG11

4 gfedc Project Tiling Scheme image? Contractor: Wilson & Company, Inc., Engineers & A... Applicable Specification: All processes, plant and deliverables sh... Licensing Restrictions: None Third Party Performed QA? Third Party QA Performed By: Independent QA performed by EC-TS Survey Section Defer, Bigelow and Giger in June and... Project Points of Contact: POC Name Type Primary Phone Shelley Silch NSDI Liaison QA Form V1.1 24AUG11

5 Project Deliverables All project deliverables must be supplied according to collection and processing specifications. The USGS will postpone the QA process when any of the required deliverables are missing. When deliverables are missing, the Contracting Officer Technical Representative (COTR) will be contacted by the Elevation/Orthoimagery Section supervisor and informed of the problem. Processing will resume after the COTR has coordinated the deposition of remaining deliverables. Collection Report Survey Report Processing Report QA/QC Report Control and Calibration Points gfedc Project Shapefile/Geodatabase Project Tiling Scheme Shapefile/Gdb Control Point Shapefile/Gdb Breakline Shapefile/Gdb Project XML Metadata Multi-File Deliverables File Type gfedc Swath LAS Files gfedc Required? gfedc XML Metadata? Quantity Intensity Image Files Required? 13 Tiled LAS Files Required? XML Metadata? 3305 gfedc Breakline Files gfedc Required? gfedc XML Metadata? Bare-Earth DEM Files Required? gfedc XML Metadata? 13 Additional Deliverables Item Bare Earth Raster Hill Shade First Return Raster First Return Raster Hill Shade Last Return Raster Last Return Raster Hill Shade Errors, Anomalies, Other Issues to document? nmlkj Yes nmlkji No None. Project Geographic Information 5 QA Form V1.1 24AUG11

6 Areal Extent: Sq Mi Grid Size: 1 meters Tile Size: 2000 meters Nominal Pulse Spacing: 1.4 meters Vertical Datum: NAVD88 meters Horizontal Datum: NAD83 meters Project Projection/Coordinate Reference System: UTM Zone 15 N meters. This Projection Coordinate Reference System is consistent across the following deliverables: Project Shapefile/Geodatabase gfedc Breaklines XML Metadata File Project Tiling Scheme Shapefile/Gdb Bare-Earth DEM XML Metadata File Checkpoints Shapefile/Geodatabase gfedc Swath LAS Files Project XML Metadata File Classified LAS Files gfedc Swath LAS XML Metadata File gfedc Breaklines Files Classified LAS XML Metadata File Bare-Earth DEM Files Swath LAS XML Metadata CRS No Swath Files Provided Breakline XML Metadata CRS No Breaklines Provided Swath LAS Files CRS No LAS files Provided Breakline Files CRS No Breaklines Provided 6 QA Form V1.1 24AUG11

7 Review Cycle This section documents who performed the QA Review on a project as well as when QA reviews were started, actions passed, received, and completed. Reviewer: JD Cox Action to Contractor Date Issue Description Review Start Date: 2/25/2013 4/18/2013 Problems with LAS classifications, DEM errors, vertical accuracy reporting and project coverage areas questions. Return Date Review Complete: Metadata Review Provided metadata files have been parsed using 'mp' metadata parser. Any errors generated by the parser are documented below for reference and/or corrective action. The Project XML Metadata file parsed withouterrors. The Classified LAS XML Metadata file parsed withouterrors. 7 QA Form V1.1 24AUG11

8 8 QA Form V1.1 24AUG11

9 Project QA/QC Report Review ASPRS recommends that checkpoint surveys be used to verify the vertical accuracy of LiDAR data sets. Checkpoints are to be collected by an independent survey firm licensed in the particular state(s) where the project is located. While subjective, checkpoints should be well distributed throughout the dataset. National Standards for Spatial Data Accuracy (NSSDA) guidance states that checkpoints may be distributed more densely in the vicinity of important features and more sparsely in areas that are of little or no interest. Checkpoints should be distributed so that points are spaced at intervals of at least ten percent of the diagonal distance across the dataset and at least twenty percent of the points are located in each quadrant of the dataset. NSSDA and ASPRS require that a minimum of twenty checkpoints (thirty is preferred) are collected for each major land cover category represented in the LiDAR data. Checkpoints should be selected on flat terrain, or on uniformly sloping terrain in all directions from each checkpoint. They should not be selected near severe breaks in slope, such as bridge abutments, edges of roads, or near river bluffs. Checkpoints are an important component of the USGS QA process. There is the presumption that the checkpoint surveys are error free and the discrepancies are attributable to the LiDAR dataset supplied. For this dataset, USGS checked the spatial distribution of checkpoints with an emphasis on the bare-earth (open terrain) points; the number of points per class; the methodology used to collect these points; and the relationship between the data supplier and checkpoint collector. When independent control data are available, USGS has incorporated this into the analysis. Checkpoint Shapefile or Geodatabase: Checkpoint Distribution Image? 9 QA Form V1.1 24AUG11

10 10 QA Form V1.1 24AUG11

11 The following land cover classes are represented in this dataset (uncheck any that do not apply): Bare Earth Tall Weeds and Crops Brush Lands and Low Trees Forested Areas Fully Covered by Trees Urban Areas with Dense Man-Made Structures There are a minimum of 20 checkpoints for each land cover class represented. Points within each class are uniformly distributed throughout the dataset. USGS wasable to locate independent checkpoints for this analysis. USGS acceptsthe quality of the checkpoint data for these LiDAR datasets. Errors, Anomalies, Other Issues to document? nmlkji Yes nmlkj No gfedc Image? Did not report Accuracy values for Bare Earth DEMs. Accuracy values reported were for the classified LAS only. USGS ran an accuracy test on Bare Earth DEM values and the results are listed below. Accuracy values are reported in terms of Fundamental Vertical Accuracy (FVA), Supplemental Vertical Accuracy(s) (SVA), and Consolidated Vertical Accuracy (CVA). Accuracy values are reported in: Meters Required FVA Value is Meters or less. Target SVA Value is 0.37 Meters or less. Required CVA Value is 0.37 Meters or less. The reported FVA of the LAS Swath data is Not Reported Meters. The reported FVA of the Bare-Earth DEM data is Not Reported Meters. 11 QA Form V1.1 24AUG11

12 SVA are required for each land cover type present in the data set with the exception of bare-earth. SVA is calculated and reported as a 95th Percentile Error. Land Cover Type SVA Value Units Tall Weeds and Crops Not Reported Meters Brush Lands and Low Trees Not Reported Meters Forested Areas Fully Covered by Trees Not Reported Meters Urban Areas with Dense Man-Made Structu... Not Reported Meters The reported CVA of this data set is: Not Reported Meters. LAS Tile File Review Classified LAS tile files are used to build digital terrain models using the points classified as ground. Therefore, it is important that the classified LAS are of sufficient quality to ensure that the derivative product accurately represents the landscape that was measured. The following was determined for classified LAS files for this project: Classified LAS Tile File Characteristics Separate folder for Classified LAS tile files Classified LAS tile files conform to Project Tiling Scheme gfedc Quantity of Classified LAS tile files conforms to Project Tiling Scheme Classified LAS tile files do not overlap Classified LAS tile files are uniform in size gfedc Classified LAS tile files have no points classified as '12' gfedc gfedc Point classifications are limited to the standard values listed below: Code 1 Processed, but unclassified 2 Bare-earth ground Description 7 Noise (low or high, manually identified, if needed) 9 Water 10 Ignored ground (breakline proximity) 11 Withheld (if the Withheld bit is not implemented in processing software) Buy up? Based on this review, the USGS does not accept at this time the classified LAS tile file data. Errors, Anomalies, Other Issues to document? nmlkji Yes nmlkj No 12 QA Form V1.1 24AUG11

13 gfedc Image? There are 32 Classifications of the Point Cloud (Classification Numbers 0 through 31.) A large majority of the points are in Classes 1,2,4,7,9, and 12. The other classes have very few points. 20 Classes have 10 or less points and 5 Classes have 44 or less points. Also, a high percentage of points are not classified ASPRS standards. For example; many Class 4 points, which are supposed to be medium vegetation, are in or near the river. One cluster of Class 4 points at the rivers edge are obviously barges, another cluster near the river appears to be structures. Class 12 is not supposed to be used, but in this data, Class 12 is overlap points, one of the more populated Classes. Bare-Earth DEM Tile File Review The derived bare-earth DEM file receives a review of the vertical accuracies provided by the data supplier, vertical accuracies calculated by USGS using supplied and independent checkpoints, and a manual check of the appearance of the DEM layer. Bare-Earth DEM files provided in the following format: ArcGrid Bare-Earth DEM Tile File Characteristics Separate folder for bare-earth DEM files DEM files conform to Project Tiling Scheme Quantity of DEM files conforms to Project Tiling Scheme DEM files do not overlap DEM files are uniform in size DEM files properly edge match gfedc Independent check points are well distributed 13 QA Form V1.1 24AUG11

14 All accuracy values reported in Meters. Reported Accuracies Land Cover Category # of Points Fundamental Vertical Confidence Interval (Accuracy z ) Required FVA = or less. Supplemental Vertical Percentile Error Target SVA = 0.37 or less. Consolidated Vertical Percentile Error Required CVA = 0.37 or less. Open Terrain 28 Not Reported Tall Weeds and Crops 96 Not Reported Brush Lands and Low Trees Forested Areas Fully Covered by Trees Urban Areas with Dense Man-Made Structures Not Reported Not Reported Not Reported Consolidated 390 Not Reported QA performed Accuracy Calculations? Calculated Accuracies Land Cover Category # of Points Fundamental Vertical Confidence Interval (Accuracy z ) Supplemental Vertical Percentile Error Target SVA = Consolidated Vertical Percentile Error Required CVA = Required FVA = or less. or less. or less. Open Terrain Tall Weeds and Crops Brush Lands and Low Trees Forested Areas Fully Covered by Trees Urban Areas with Dense Man-Made Structures Consolidated QA Form V1.1 24AUG11

15 Based on this review, the USGS does not recommend the bare-earth DEM files for inclusion in the 1/3 Arc-Second National Elevation Dataset. Based on this review, the USGS does not accept at this time the bare-earth DEM files. Bare-Earth DEM Anomalies, Errors, Other Issues Errors, Anomalies, Other Issues to document? nmlkji Yes nmlkj No The river rises over 2.5m in about 200m and appears out of its normal banks. 15 QA Form V1.1 24AUG11

16 Typical small Bridge, separate berms, clear the channel. Culvert, not a Bridge, connect berms 16 QA Form V1.1 24AUG11

17 Culvert, not a Bridge, connect berms Culvert, not a Bridge, connect berms 17 QA Form V1.1 24AUG11

18 Culvert, not a Bridge, connect berms Culvert, not a Bridge, connect berms 18 QA Form V1.1 24AUG11

19 Culvert, not a Bridge, connect berms Image? Culvert, connect berms 19 QA Form V1.1 24AUG11

20 Culvert, connect berms 20 QA Form V1.1 24AUG11

21 Culvert, connect berms Culvert, connect berms 21 QA Form V1.1 24AUG11

22 Culverts, not Bridges, connect berms Fill data voids 22 QA Form V1.1 24AUG11

23 Small Bridge, Separate roadway 23 QA Form V1.1 24AUG11

24 The Bridge is not this long. The Bridge has vertical concrete retaining walls before the underpass which give a bridge like signature. Replace some of the elevated roadway Bridge, separate the roadway, clear the channel 24 QA Form V1.1 24AUG11

25 Bridge, separate the roadway, clear the channel Bridge, at bottom left of center, separate the roadway, clear the channel 25 QA Form V1.1 24AUG11

26 Bridge, separate the roadway 26 QA Form V1.1 24AUG11

27 Bridges, separate the roadway 27 QA Form V1.1 24AUG11

28 Bridge, separate roadway, clear channel 28 QA Form V1.1 24AUG11

29 Bridge, right center, separate roadway, clear channel 29 QA Form V1.1 24AUG11

30 Fill data voids Fill data voids 30 QA Form V1.1 24AUG11

31 Fill data voids 31 QA Form V1.1 24AUG11

32 Fill data voids Fill data voids 32 QA Form V1.1 24AUG11

33 Fill data voids 33 QA Form V1.1 24AUG11

34 Fill data voids Bluff to bluff coverage? Project boundary is in the River channel. Obviously missing data. 34 QA Form V1.1 24AUG11

35 Project Boundary in the River? Data missing. 35 QA Form V1.1 24AUG11

36 Bridge, separate roadway, clear channel Image? 36 QA Form V1.1 24AUG11

37 Bridge, separate roadway, clear channel Image? 37 QA Form V1.1 24AUG11

38 Culvert, join berms Image? 38 QA Form V1.1 24AUG11

39 Culvert, join berms Image? 39 QA Form V1.1 24AUG11

40 Why is there a difference in detail in the image, nothing on the ground can account for this. 40 QA Form V1.1 24AUG11

41 Center of east edge, Culvert, join berms Bridge, separate the roadway, clear the channel 41 QA Form V1.1 24AUG11

42 Culvert, join berms Culvert, join berms 42 QA Form V1.1 24AUG11

43 Bridge, separate roadway, clear the channel Culvert, join berms 43 QA Form V1.1 24AUG11

44 Culvert, join berms 44 QA Form V1.1 24AUG11

45 Culvert, join berms Culvert, join berms 45 QA Form V1.1 24AUG11

46 Culvert, join berms Internal Note: PROJECT GENERAL NOTES: 1. There were no breaklines, therefore no hydroflattening provided anywhere in the project. 2. The processed data did not extend beyond the project boundaries anywhere. USGS Specifications require a 100m extension past the project boundary. 3. The Project Description defines the project area as "bluff to bluff coverage of the River valleys. This data will primarily be used for watershed modeling, storm water planning, floodplain determination, and structure design and estimation." However, the project as delivered, occasionally places the project boundary in the river channel and in many other places the boundary does not extend to the bluffs. Making it of little, limited, or no use for its stated primary purposes. 46 QA Form V1.1 24AUG11

47 This is the end of the report. QA Form V1.4 12OCT11.xsn 47 QA Form V1.1 24AUG11