Puget Sound LiDAR Consortium
TerraPoint
2003
Lewis County 2003 - All Returns LiDAR ASCII Points
vector digital data
http://lidar.cr.usgs.gov
http://seamless.usgs.gov
"The all returns ASCII files contain the X,Y,Z values of all the LiDAR
returns collected during the survey mission. In addition each return also
has a time stamp, return number, ellipsoidal height and scan angle. The
elevation values are in feet. TerraPoint surveyed and created this data
for the Puget Sound LiDAR Consortium under contract."
"The LiDAR all returns ASCII files can be used to create DEM and also
to extract topographic data in software that does not support raster data.
Other surface features can also be extracted with custom applications.
This high accuracy data can be used at scales up to 1:12000 (1 inch =
1,000 feet). LiDAR data has a wide range of uses such as earthquake hazard
studies, hydrologic modeling, forestry, coastal engineering, roadway and
pipeline engineering, flood plain mapping, wetland studies, geologic
studies and a variety of analytical and cartographic projects."
The data obtained through The Seamless Server is considered to be the "best available" data from USGS. Historical data and other data may be obtained by contacting Customer Services, Center for Earth Resources Observation & Science, at 1-800-252-4547. Information in quotation marks is taken directly from the original metadata document.
20030211
20030329
ground condition
None planned
-121.000000036489
-120.937500036431
48.3124999497571
48.2499999496989
None
LiDAR
Light Detection And Ranging
ASCII
Text files
all returns
puget sound lidar consortium
point cloud
elevation data
topography
surface
ALSM
high-resolution
FF
raw data
point cloud
ISO 19115 Category
imageryBaseMapsEarthCover
geoscientificInformation
location
U.S. Department of Commerce, 1995, Countries, dependencies, areas of special sovereignty, and their principal administrative divisions, Federal Information Processing Standard 10-4,): Washington, D.C., National Institute of Standards and Technology
United States
U.S.
US
U.S. Department of Commerce, 1987, Codes for the Identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard (FIPS) 5-2): Washington, D.C., National Institute of Standards and Technology.
WA
None
Washington State
Lewis County
Snoqualmie National Forest
Mineral
Alder Lake
Western Washington
none
"Considerable care has been taken to see that these data and derived
images are as accurate as possible. We believe most of the data is adequate
for determination of flood hazards, for geologic mapping, for hydrologic
modeling, for determination of slope angles, for modeling of radio-wave
transmission, and similar uses with a level of detail appropriate to a
horizontal scale of 1:12,000 (1 inch = 1,000 feet) or smaller and vertical
accuracy on the order of a foot. Locally, the data is of considerably poorer
quality.
In the bare earth DEMs where there are few survey points (i.e. bare-earth
surfaces in heavy timber, where there are few ground reflections), TINing
the points produces large triangular facets where the surface has
significant curvature. Similar, though finer, textures are evident where
vegetation reflections are incompletely filtered. Elevations are likely to
be less accurate in these areas.
Top surface DEMs where project areas meet may have different vegetation
heights. Survey projects are flown during winter leaf-off season; therefore
adjacent project areas may be 1 or more years apart. Since vegetation is in
a state of constant change it is expected to have differing vegetation
heights in these areas.
LiDAR data values for water surfaces are not valid elevation values.
Lidar surveying produces few survey points on water. Mirror-like surfaces
fail to scatter the laser beam and unless the beam is perpendicular to the
surface, no light is reflected back to the detector. Or intense reflections
may lead to negative blunders, points that are too low. Interpolation
between the nearest on-land points and sparse water points produces large
triangular facets that may not accurately reflect the water-surface
elevation. Where the water surface is surveyed adequately, adjacent swaths
may be flown at different tide stages, producing swath-parallel cliffs.
Ideally, lidar topography would be clipped to eliminate all open-water
areas, but at present this is very labor-intensive.
User should carefully determine the place-to-place accuracy and fitness
of these data for your particular purposes. For many purposes a site- and
use-specific field survey will be necessary." There is no guarantee of warranty concerning the accuracy of the data. Users should be aware that temporal changes may have occurred since this data set was collected and that 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 its limitations. Acknowledgement of the originating agencies would be appreciated in products derived from these data. Any user who modifies the data is obligated to describe the types of modifications they perform. User specifically agrees not to misrepresent the data, nor to imply that changes made were approved or endorsed by the U.S. Geological Survey. Please refer to http://www.usgs.gov/privacy.html for the USGS disclaimer.
Jason Stoker
USGS / EROS
Senior Scientist
mailing and physical address
USGS Center for Earth Resources Observation & Science
47914 252nd Street
Sioux Falls
SD
57198-0001
USA
605-594-2579
jstoker@usgs.gov
Please refer to the Processing Information contacts for questions on original data.
"Please credit the Puget Sound LiDAR Consortium (PSLC) for these data.
The PSLC is supported by the Puget Sound Regional Council, the National
Aeronautical and Space Administration (NASA), the United States Geological
Survey (USGS) and numerous partners in local, state, and tribal government."
None
Unclassified
N/A
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.1.0.722
Elevations are recorded in floating-point feet and the vertical datum
is NAVD88. There are no other attribute tables.
"Puget Sound Lidar Consortium evaluates logical consistency of
high-resolution lidar elevation data with three tests: examination of file
names, file formats, and mean and extreme values within each file; internal
consistency of measured Z values in areas where survey swaths overlap; and
visual inspection of shaded-relief images calculated from bare-earth models.
File names, formats, and values: All file naming convention and file
formats are check for consistency.
Internal Consistency Analysis This analysis calculates and displays the
internal consistency of tiled multi-swath (many-epoch) LiDAR data. The input
for this analysis is the All-return ASCII data, but it only uses the first
returns. The data is divided into swaths, or flightlines, and they are
compared with each other. Since the contract specifications require 50%
sidelaps, it means that all areas should have been flown twice. The results
of this analysis is to verify that the data was generally flown to obtain
the 50% sidelaps, that there are no gap between flightlines and also that
overlapping flightlines are consistent in elevation values.
Visual inspection of shaded-relief images: During the visual inspection,
hillshades are derived from the bare earth DEMs. The hillshades are examined
for any obvious data errors such as blunders, border artifacts, gaps between
data quads, no-data gaps between flight lines, hillscarps, land shifting due
to GPS time errors, etc. The data is examined a scale range of 1:4000 to
1:6000. During this process we also compare the data to existing natural
features such as lakes and rivers and also to existing infrastructure such
as roads. Orthophotos area also used during this phase to confirm data
errors. If any of these data errors are found, they are reported to
TerraPoint for correction."
Elevation data has been collected for all areas inside project
boundaries.
Not applicable for pure elevation data: every XY error has an
associated Z error.
"Puget Sound Lidar Consortium evaluates vertical accuracy with two
measures: internal consistency and conformance with independent ground
control points.
Internal Consistency: Data are split into swaths (separate
flightlines), a separate surface is constructed for each flightline, and
where surfaces overlap one is subtracted from another. Where both
surfaces are planar, this produces a robust measure of the
repeatability, or internal consistency, of the survey. The average error
calculated by this means, robustly determined from a very large sample,
should be a lower bound on the true error of the survey as it doesn't
include errors deriving from a number of sources including: 1)
inaccurately located base station(s), 2) long-period GPS error, 3)
errors in classification of points as ground and not-ground
(post-processing), 4) some errors related to interpolation from
scattered points to a continous surface (surface generation).
Conformance with independent ground control points: Bare-earth
surface models are compared to independently-surveyed ground control
points (GCPs) where such GCPs are available. The purpose of the ground
control evaluation is to assess that the bare earth DEMs meet the
vertical accuracy specification in the PSLC contract with TerraPoint:
"The accuracy specification in the contract between the Puget Sound
LiDAR Consortium and TerraPoint is based on a required Root Mean Square
Error (RMSE) 'Bare Earth' vertical accuracy of 30 cm for flat areas in
the complete data set. This is the required result if all data points in
flat areas were evaluated. Because only a small sample of points is
evaluated, the required RMSE for the sample set is adjusted downward per
the following equation from the FEMA LiDAR specification (adjusted from
the 15 cm RMSE in the FEMA specification to 30 cm to accommodate the
dense vegetation cover in the Pacific Northwest)."
During this step, the bare earth DEMs were compared with existing
survey benchmarks. The differences between the LiDAR bare earth DEMs and
the survey points are calculated and the final results are first
summarized in a graph that illustrates how the dataset behaves as whole.
The graph illustrates how close the DEM elevation values were to the
ground control points. The individual results were aggregated and used
in the RMSE calculations. The results of the RMSE calculations are the
measure that makes the data acceptable for this particular specification
in the contract."
30
30 cm or less in flat open areas
"Root mean square Z error in open, near-horizontal areas, as
specified by contract. Our assessment suggests that all data meet this
standard. Accuracy may be significantly less in steep areas and under
heavy forest canopy. Accuracy appears to be significantly better for
data acquired in early 2003 and afterward, to which in-situ
calibration has been applied."
"Acquisition.
Lidar data were collected in leaf-off conditions (approximately 1 November - 1 April) from a fixed-wing aircraft flying at a nominal height of 1,000 meters above ground surface. Aircraft position was monitored by differential GPS, using a ground station tied into the local geodetic framework. Aircraft orientation was monitored by an inertial measurement unit. Scan angle and distance to target were measured with a scanning laser rangefinder. Scanning was via a rotating 12-facet pyramidal mirror; the laser was pulsed at 30+ KHz, and for most missions the laser was defocussed to illuminate a 0.9m-diameter spot on the ground. The rangefinder recorded up to 4 returns per pulse. Flying height and airspeed were chosen to result in on-ground pulse spacing of about 1.5 m in the along-swath and across-swath directions. Most areas were covered by two swaths, resulting in a nominal pulse density of about 1 per square meter."
Unknown
TerraPoint
mailing address
25216 Grogans Park Drive
The Woodlands
TX
77380
USA
281-364-4080
www.terrapoint.com
"Processing.
GPS, IMU, and rangefinder data were processed to obtain XYZ
coordinates of surveyed points. For data acquired after January 2003, survey data from areas of swath overlap were analysed to obtain best-fit in-situ calibration parameters that minimize misfit between overlapping swaths. This reduces vertical
inconsistency between overlappoing swaths by about one-half.
Heights were translated from ellipsoidal to orthometric (NAVD88)
datums via GEOID99"
Unknown
TerraPoint
mailing address
25216 Grogans Park Drive
The Woodlands
TX
77380
USA
+1.281.364.4080
www.terrapoint.com
"ASCII file generation
All Point returns with all their attributes were directly exported into ASCII files. These were first divided into USGS quarter quads (3.25 minute by 3.25 minute) and then in 25 tiles per quarter quad."
Unknown
TerraPoint
mailing address
25216 Grogans Park Drive
The Woodlands
TX
77380
USA
+1.281.364.4080
www.terrapoint.com
The metadata were imported and updated for display through the Seamless Data Distribution System at <http://seamless.usgs.gov>
2006
U.S. Geological Survey
Customer Service Representative
mailing and physical address
USGS Center for Earth Resources Observation & Science
47914 252nd Street
Sioux Falls
SD
57198-0001
USA
605-594-6151
1-800-252-4547
605-594-6933
605-594-6589
custserv@usgs.gov
0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
PSLC LiDAR data is broken down into USGS quarter quads. ASCII data
is further broken down into 25 tiles per quarter quad. Each quarter
quadrangle issubdivided into a 5 x 5 array of tiles organized from
upper-left to lower-right as follows:01 02 03 04 0506 07 08 09
1011 12 13 14 1516 17 18 19 2021 22 23 24 25The two-digit
tile number is appended to the end of the file name.
See index
files in PSLC website for further reference.
Point
State Plane Coordinate System 1983
Washington South, FIPS 4602
45.833333
47.333333
-120.500000
45.333333
1640416.666667
0.000000
coordinate pair
3.28
3.28
survey feet
North American Datum of 1983 with 1991 Adjustments (HARN)
Geodetic Reference System 80
6378137.000000
298.257222
North American Vertical Datum of 1988
0.49
feet
Implicit coordinate
"The delimiting format for these files is fixed width. The field names
in corresponding order are:
gpsweek, gpstime, x, y, z, total_return#, return#, scanangle,
intensity, classcode gpsweek = GPSweek, refer to the GPS Calendar from NGS at
www.ngs.noaa.gov/CORS/Gpscal.html
gpstime = Time Stamp in seconds. Each GPS Week has 604,800 seconds and
each day has 86,400 seconds.
x = Easting Coordinate
y = Northing Coordinate
z = Orthometric elevation derived from the NGS Survey Geoid Model
Geoid99.
total_return# = total number of returns per pulse *
return# = Return Number. Each pulse can have up to 4 returns. *
scanangle = Scan Angle
intensity = Light Intensity classcode = Classification code. (B =
Blunder, G = Ground, V = vegetation, S = surface, buildings or structures,
N = not ground, undifferentiated veg. bldg, struc)
* Up to four returns can be recorded per laser pulse; total_return# is
the total returns for a pulse (up to a maximum of 4). return# is assigned
as a number from 1 to 7 in a scheme that identifies which return is the
last return recorded for a pulse: 1 first return with subsequent
returns detected
2 second return with subsequent returns detected
3 third return with subsequent returns detected
4 fourth return
5 first return with no subsequent returns detected
6 second return with no subsequent returns detected
7 third return with no subsequent returns detected"
Not provided.
U.S. Geological Survey
Customer Services Representative
mailing and physical address
USGS Center for Earth Resources Observation & Science
47914 252nd Street
Sioux Falls
SD
57198-0001
USA
605/594-6151
1-800-252-4547
605/594-6933
605/594-6589
custserv@usgs.gov
0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
The USGS "Distribution" 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, please contact:
Mr. Jason Stoker
Senior Scientist
USGS Center for Earth Resources Observation & Science
phone: 605-594-2579
email: jstoker@usgs.gov
Please refer to the Processing Information contacts for questions on original data.
Downloadable Data
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.
Arc/Info Export Format and/or ArcView Shapefile
ArcGIS 9.1
ASCII
0.001
http://seamless.usgs.gov
The URL <http://seamless.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 Seamless Data Distribution System 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.
Not available for dissemination
None
Variable
ESRI ArcGIS Suite and/or Arc/Info or other compatible software, and supporting operating systems.
unknown
20060306
U.S. Geological Survey
Customer Services Representative
mailing and physical address
USGS Center for Earth Resources Observation & Science
47914 252nd Street
Sioux Falls
SD
57198-0001
USA
605/594-6151
1-800-252-4547
605/594-6933
605/594-6589
custserv@usgs.gov
0800 - 1600 CT, M - F (-6h CST/-5h CDT GMT)
The above is the contact information for the USGS Center for Earth Resources Observation and Science 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
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998
local time
None
None
None
Unclassified
None
http://www.esri.com/metadata/esriprof80.html
ESRI Metadata Profile