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Linear Unit: Foot_US (0.304801)
NAD_1983_2011_StatePlane_Illinois_East_FIPS_1201_Ft_US
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DBO.Topo_Contours21
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Ayres Associates
(608) 443-1200
5201 E. Terrace Drive, Suite 200
Madison
Wisconsin
53718
U.S.A.
20220601
ArcGIS Metadata
1.0
Ayres Associates
(608) 443-1200
5201 E Terrace Drive, Suite 200
Madison
Wisconsin
53718
U.S.A.
DerringerA@AyresAssociates.com
Please contact the organization contact for help in acquiring data.
Feature Class
DBO.Topo_Contours21
2021-08-13
Ayres Associates
Ayres Associates
Madison, WI
The Will County, IL lidar project area covers approximately 887 square miles. The lidar data was acquired at an aggregate nominal point density (ANPD) of 10. Project specifications are based on Will County requirements. The data was developed based on a horizontal projection/datum of NAD83(2011) / Illinois State Plane East Zone (ftUS) (EPSG Code: 3435), and vertical datum of NAVD88 - Geoid12B (US Survey Feet). LiDAR data was acquired using a Optech Galaxy T2000 sensor from March 29th, 2021 to April 13, 2021 in 8 total lifts. Acquisition occurred with leaves absent from deciduous trees, when no snow was present on the ground, and with rivers at or below normal levels.
Becky Colwell-Ongenae
Will County
GIS Manager
815-774-6341
302 N. Chicago St.
Joliet
IL
60432
U.S.A.
rcolwell@willcountyillinois.com
Will County
City of Joilet
Illinois
contours
surface data
terrain data
bare earth
1-foot contours
elevation
topography
Lidar
contours
surface data
terrain data
Will County
bare earth
1-foot contours
City of Joilet
elevation
topography
Illinois
Lidar
Distributor assumes no liability for misuse of data.
No restrictions apply to these data.
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be aware that temporal changes may have occurred since this dataset was collected and that some parts of these data may no longer represent actual surface conditions.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.
ground condition
2021-03-29
2021-04-13
0.000000
874.000000
-88.262039
-87.521435
41.19884
41.729205
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874.000000
Version 6.2 (Build 9200) ; Esri ArcGIS 10.9.1.28388
1
-88.266711
-87.516495
41.732895
41.195129
Spatial consistency of coverage of the Will County QL1 LiDAR (2021) project area was maintained throughout the dataset.
Spatial consistency of coverage of the Will County QL1 LiDAR (2021) project area was maintained throughout the dataset.
Formal attribute accuracy tests were conducted.
The project specifications require the vertical accuracy of the LiDAR data to be calculated and reported according to Non-vegetated Vertical Accuracy (NVA) and Vegetated Vertical Accuracy (VVA) classifications. The required NVA for this project is 19.6 cm (0.643 survey feet) calculated at the 95 percent confidence level (AccuracyZ). The 95 percent confidence level statistic is derived according to National Standards for Spatial Data Accuracy (NSSDA) methodologies using RMSEz * 1.9600. This requirement is for the vertical accuracy testing of the raw swath lidar data and the derived digital elevation model (DEM). The AccuracyZ statistic is assessed and reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines. The NVA was tested with 63 checkpoints located in bare earth and urban (non-vegetated) areas. The required VVA for this project is 29.4 cm (0.965 survey feet) calculated 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 requirement is for the vertical accuracy testing of the derived digital elevation model (DEM). The VVA was tested with 50 checkpoints located in tall weeds/crops and brushlands/low trees (vegetated) areas.
0.059 meters NVA at the 95 percent confidence level. The NVA of the raw swath was calculated using 63 independent checkpoints located in the Bare Earth and Urban land cover categories.
0.059
LiDAR processing utilizes several software packages, including GeoCue and the TerraSolid suite of processing components. The GeoCue software is a database management system for housing the LiDAR dataset (usually multiple gigabytes in size). GeoCue incorporates a thorough checklist of processing steps and quality assurance/quality control (QA/QC) procedures that assist in the LiDAR workflow. The TerraSolid software suite is used to automate the initial classification of the LiDAR point cloud based on a set of predetermined parameters. Lidar technicians refer to ground cover research (natural and cultural features) within the project area and determine algorithms most suitable for the initial automated LiDAR classification. (Some algorithms/filters recognize the ground in forests well, while others have greater capability in urban areas). During this process each point is given an initial classification (e.g., as ground, vegetation, or noise) based on the point's coordinates and the relation to its neighbors. Classifications to be assigned include all those outlined by ASPRS standards. The initial classifications produce a coarse and inexact dataset, but offer an adequate starting point for the subsequent manual classification procedure. During this step, "overlap" points are automatically classified (those originating from neighboring flightlines) using information gathered from the ABGPS and IMU data. Any duplicate points existing from adjacent flightlines are removed during this process. Hydrographic breaklines are collected using LiDARgrammetry to ensure hydroflattened water surfaces. This process involves manipulating the LiDAR data's intensity information to create a metrically sound stereo environment. From this generated "imagery", breaklines are photogrammetrically compiled. Breakline polygons are created to represent open water bodies. The LiDAR points that fall within these areas are classified as "water." All hydrographic breaklines include a 3.125 foot buffer, with the Class 2 (bare earth) points being re-classified as Class 20 (ignored ground). TerraSolid is further used for the subsequent manual classification of the LiDAR points allowing technicians to view the point cloud in a number of ways to ensure accuracy and consistency of points and uniformity of point coverage. The TIN was processed to create one foot contours.
2021-08-13
1471094
dataset
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1471094
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