<?xml version="1.0" encoding="ISO-8859-1"?><!DOCTYPE metadata SYSTEM "http://www.fgdc.gov/metadata/fgdc-std-001-1998.dtd"><metadata>
<idinfo>
<citation>
<citeinfo>
<origin>Watershed Sciences, Inc.</origin>
<pubdate>20101116</pubdate>
<title>LiDAR Ground Return Data, Flathead Basin, Montana 2009</title>
<pubinfo>
<pubplace>Helena, MT</pubplace>
<publish>Montana State Library</publish>
</pubinfo>
<onlink>http://nris.mt.gov/Flathead_2009</onlink>
</citeinfo>
</citation>
<descript>
<abstract>These data files are the "ground return" LiDAR point cloud data collected in the Flathead Basin, Montana, between September 22 and September 29, 2009.  The study area includes the Flathead Valley floor, the area around Polson, and the shorelines of Flathead Lake, Whitefish Lake, and Swan Lake.  This data only includes points that were identified as being on the ground surface - all structures and vegetation have been removed.

The data is in LiDAR LAS format, as described at http://www.asprs.org/society/committees/standards/lidar_exchange_format.html

The horizontal coordinate system of the data is Montana State Plane Coordinates, NAD83 HARN, and the units are U.S. Survey Feet.  The vertical Datum is NAVD88 (Geoid03).

The contractor's report giving a complete explanation of the data collection and quality control processes is at http://nris.mt.gov/Flathead_2009/Reports.asp.</abstract>
<purpose>Provide high resolution terrain elevation and land cover elevation data.</purpose>
</descript>
<timeperd>
<timeinfo>
<rngdates>
<begdate>20090922</begdate>
<enddate>20090929</enddate>
</rngdates>
</timeinfo>
<current>ground condition</current>
</timeperd>
<status>
<progress>Complete</progress>
<update>None planned</update>
</status>
<spdom>
<bounding>
<westbc>
-114.47</westbc>
<eastbc>
-113.83</eastbc>
<northbc>
48.49</northbc>
<southbc>
47.65</southbc>
</bounding>
</spdom>
<keywords>
<theme>
<themekt>ISO 19115 Topic Category</themekt>
<themekey>elevation</themekey>
</theme>
<theme>
<themekey>LiDAR</themekey>
<themekey>Light Detection and Ranging</themekey>
<themekey>DEM</themekey>
<themekey>digital terrain model</themekey>
<themekey>Montana Department of Natural Resources and Conservation</themekey>
<themekey>elevation data</themekey>
<themekey>topography</themekey>
<themekey>bare earth</themekey>
<themekey>high-resolution</themekey>
<themekey>DTM</themekey>
</theme>
<place>
<placekey>Montana</placekey>
<placekey>Flathead County</placekey>
<placekey>Lake County</placekey>
<placekey>Flathead Basin</placekey>
</place>
</keywords>
<accconst>None</accconst>
<useconst>This data set is provided "as-is" without warranty of any kind. The user assumes responsibility to determine the suitablilty of the data for their purposes. The State Library makes no representations or warranties whatsoever with respect to the accuracy or completeness of this data set and assumes no responsibility for the suitability of this data set for a particular purpose; and the Library will not be liable for any damages incurred as a result of errors in this data set.</useconst>
<ptcontac>
<cntinfo>
<cntorgp>
<cntorg>Montana Department of Natural Resources and Conservation</cntorg>
<cntper>Stephen Story</cntper>
</cntorgp>
<cntaddr>
<addrtype>mailing and physical address</addrtype>
<address>PO Box 201601</address>
<address>1424 9th Ave.</address>
<city>Helena</city>
<state>MT</state>
<postal>59620-1601</postal>
<country>USA</country>
</cntaddr>
<cntvoice>406-444-6664</cntvoice>
<cntemail>sestory@mt.gov</cntemail>
</cntinfo>
</ptcontac>
</idinfo>
<dataqual>
<logic>LiDAR flight lines have been examined to ensure that there was at least 50% sidelap, there are no gaps between flightlines, and overlapping flightlines have consistent elevation values.

Shaded relief images have been visually inspected for data errors such as pits, border artifacts, gaps, and shifting.  The data was examined at a 1:2000 scale.</logic>
<posacc>
<horizpa>
<qhorizpa>
<horizpae>See LiDAR data report.</horizpae>
</qhorizpa>
</horizpa>
<vertacc>
<qvertpa>
<vertaccv>RMSE = 0.118 feet (0.036 meters)</vertaccv>
<vertacce>The Root Mean Square Error (RMSE) of the data set is 0.118 feet (0.036 meters).  Accuracy was assessed using 4229 ground survey (real time kinematic) points.  Please see LiDAR data report for a discussion of statistics related to these datasets.</vertacce>
</qvertpa>
</vertacc>
</posacc>
<lineage>
<procstep>
<procdesc>The LiDAR data was collected from September 22nd - 29th, 2009.   The survey used a Leica ALS50 Phase II laser system, with a scan angle of plus or minus 15 degrees from nadir with a pulse rate designed to yield an average native density of at least 4 points per square meter over terrestrial surfaces.  The study area was surveyed with an opposing flight line side-lap of at least 50 percent to reduce laser shadowing and increase surface laser painting.  The system allows up to 4 range measurements (returns) per pulse, and all discernable returns were processed for the output dataset.

To accurately solve for laser point position, the positional coordinates of the airborne sensor and the attitude of the aircraft were recorded continuously throughout the LiDAR data collection mission.  Aircraft position was measured twice per second by an onboard differential GPS unit.  Aircraft attitude ws measured 200 times per second from an onboard inertial mesasurement unit.  To allow for post processing correction and calibration, aircraft/sensonr position and attitude data are indexed by GPS time.</procdesc>
<proccont>
<cntinfo>
<cntorgp>
<cntorg>Watershed Sciences</cntorg>
</cntorgp>
<cntaddr>
<addrtype>mailing and physical address</addrtype>
<address>257B SW Madison Ave</address>
<city>Corvallis</city>
<state>OR</state>
<postal>97333</postal>
</cntaddr>
<cntvoice>541-752-1204</cntvoice>
<cntemail>watershedsciences.com</cntemail>
</cntinfo>
</proccont>
</procstep>
<procstep>
<procdesc>
Laser point coordinates were computed using the IPAS and ALS Post Processor software suites based on independent data from the LiDAR system (pulse time, scan angle), and aircraft trajectory data (SBET). Laser point returns (first through fourth) were assigned an associated (x, y, z) coordinate along with unique intensity values (0-255). The data were output into large LAS v. 1.2 files; each point maintains the corresponding scan angle, return number (echo), intensity, and x, y, z (easting, northing, and elevation) information.

These initial laser point files were too large for subsequent processing. To facilitate laser point processing, bins (polygons) were created to divide the dataset into manageable sizes (less than 500 MB). Flightlines and LiDAR data were then reviewed to ensure complete coverage of the survey area and positional accuracy of the laser points.

Laser point data were imported into processing bins in TerraScan, and manual calibration was performed to assess the system offsets for pitch, roll, heading and scale (mirror flex). Using a geometric relationship developed by Watershed Sciences, each of these offsets was resolved and corrected if necessary.

LiDAR points were then filtered for noise, pits (artificial low points), and birds (true birds as well as erroneously high points) by screening for absolute elevation limits, isolated points and height above ground. Each bin was then manually inspected for remaining pits and birds and spurious points were removed. In a bin containing approximately 7.5-9.0 million points, an average of 50-100 points are typically found to be artificially low or high. Common sources of non-terrestrial returns are clouds, birds, vapor, haze, decks, brush piles, etc.

Internal calibration was refined using TerraMatch. Points from overlapping lines were tested for internal consistency and final adjustments were made for system misalignments (i.e., pitch, roll, heading offsets and scale). Automated sensor attitude and scale corrections yielded 3-5 cm improvements in the relative accuracy. Once system misalignments were corrected, vertical GPS drift was then resolved and removed per flight line, yielding a slight improvement (less than 1 cm) in relative accuracy.

The TerraScan software suite is designed specifically for classifying near-ground points (Soininen, 2004). The processing sequence began by ‘removing’ all points that were not ‘near’ the earth based on geometric constraints used to evaluate multi-return points. The resulting bare earth (ground) model was visually inspected and additional ground point modeling was performed in site-specific areas to improve ground detail. This manual editing of grounds often occurs in areas with known ground modeling deficiencies, such as: bedrock outcrops, cliffs, deeply incised stream banks, and dense vegetation. In some cases, automated ground point classification erroneously included known vegetation (i.e., understory, low/dense shrubs, etc.). These points were manually reclassified as non-grounds.
</procdesc>
<proccont>
<cntinfo>
<cntorgp>
<cntorg>Watershed Sciences</cntorg>
</cntorgp>
<cntaddr>
<addrtype>mailing and physical address</addrtype>
<address>257B SW Madison Ave</address>
<city>Corvallis</city>
<state>OR</state>
<postal>97333</postal>
</cntaddr>
<cntvoice>541-752-1204</cntvoice>
<cntemail>watershedsciences.com</cntemail>
</cntinfo>
</proccont>
</procstep>
</lineage>
</dataqual>
<spref>
<horizsys>
<planar>
<mapproj>
<mapprojn>Lambert Conformal Conic</mapprojn>
<lambertc>
<stdparll>45.000000</stdparll>
<stdparll>49.000000</stdparll>
<longcm>-109.500000</longcm>
<latprjo>44.250000</latprjo>
<feast>1968500.000000</feast>
<fnorth>0.000000</fnorth>
</lambertc>
</mapproj>
<planci>
<plance>coordinate pair</plance>
<coordrep>
<absres>0.000000</absres>
<ordres>0.000000</ordres>
</coordrep>
<plandu>U.S. Survey Feet</plandu>
</planci>
</planar>
<geodetic>
<horizdn>D_North_American_1983_HARN</horizdn>
<ellips>Geodetic Reference System 80</ellips>
<semiaxis>6378137.000000</semiaxis>
<denflat>298.257222</denflat>
</geodetic>
</horizsys>
<vertdef>
<altsys>
<altdatum>NAVD88 (Geoid 03)</altdatum>
<altunits>U.S. Survey Feet</altunits>
</altsys>
</vertdef>
</spref>
<distinfo>
<distrib>
<cntinfo>
<cntorgp>
<cntorg>Montana State Library</cntorg>
</cntorgp>
<cntaddr>
<addrtype>mailing address</addrtype>
<address>PO Box 201800</address>
<city>Helena</city>
<state>MT</state>
<postal>59620-1800</postal>
</cntaddr>
<cntvoice>406-444-5355</cntvoice>
<cntemail>nris@mt.gov</cntemail>
</cntinfo>
</distrib>
<resdesc>Downloadable Data</resdesc>
<stdorder>
<digform>
<digtinfo>
</digtinfo>
<digtopt>
<onlinopt>
<computer>
<networka>
<networkr>http://nris.mt.gov/flathead_2009</networkr>
</networka>
</computer>
</onlinopt>
</digtopt>
</digform>
</stdorder>
</distinfo>
<metainfo>
<metd>20101201</metd>
<metc>
<cntinfo>
<cntorgp>
<cntorg>Watershed Sciences, Inc.</cntorg>
</cntorgp>
<cntaddr>
<addrtype>mailing address</addrtype>
<address>257 B SW Madison Ave</address>
<city>Corvallis</city>
<state>OR</state>
<postal>97333</postal>
<country>USA</country>
</cntaddr>
<cntvoice>541-752-1204</cntvoice>
<cntemail>watershedsciences.com</cntemail>
</cntinfo>
</metc>
<metstdn>FGDC Content Standards for Digital Geospatial Metadata</metstdn>
<metstdv>FGDC-STD-001-1998</metstdv>
</metainfo>
</metadata>
