U.S. Geological Survey
2007
Sarasota County, Florida - Aerial Topographic Mapping
vector digital data
http://seamless.usgs.gov
http://lidar.cr.usgs.gov
"This metadata record describes the ortho & lidar
mapping of Sarasota County, FL. The mapping consists of
lidar data collected using a Leica ALS-40 Lidar Sensor,
contour generation, and production of natural color
orthophotography with a 30-cm GSD using imagery
collected with a Leica ADS-40 Aerial Digital Camera."
"The purpose of this mapping project is to create and
deliver digital terrain models (DTM), capable of generating
one-foot contours and to produce orthophotography at a
200' scale."
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 any original documentation available.
20050917
publication date
Unknown
-82.4375002350423
-82.3750002349841
27.1250002185208
27.0625002184626
None.
LiDAR
Light Detection And Ranging
elevation data
topography
surface
high-resolution
raw data
ISO 19115 Category
imageryBaseMapsEarthCover
010
geoscientificInformation
008
location
013
American Society of Photogrammetry and Remote Sensing
National Standards for Spatial Digital Accuracy (NSSDA)
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.
FL
Geographic Names Information System
Florida State
Sarasota County
Sarasota
None
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be aware that temporal changes may have occurred since this data set was collected and that some parts of this data may no longer represent actual surface conditions.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
EarthData International
None
Unclassified
N/A
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.1.0.722
"The generated contours were NOT produced to be fully
compliant with NSSDA accuracy standards for 2' contours.
Contours were generated from lidar DTM as is without the
benefit of photogrammetric breakline support. Lidar
elevation data meets National Map Accuracy Standards.
The digital orthophotography meets national mapping
accuracy standards for 200 scale product."
"Compliance with the accuracy standard was ensured by
the placement of GPS ground control prior to the
acquisition of aerial photography. The following checks
were performed.
1. The ground control and airborne GPS data stream were
validated through a fully analytical bundle aerotriangulation
adjustment. The residuals of the adjustment met the
required standards for accuracy which are 1 part in
10,000 of the flying height for the horizontal position (X and
Y) and 1 part in 9,000 or better of the flying height in
elevation (Z).
2. The DTM (Digital Terrain Model) data were checked
against the project control.
The technician visited and confirmed the accuracy of the
project mass points during initial processing.
3. Digital orthophotography was validated through an
inspection of edge matching and visual inspection for
image quality.
The following software is used for validation of the
1. Aerotriangulation - ISTAR Processing
2. DTM data - Z/I Imaging SSK
3. Digital Orthophotography - Z/I Imaging OrthoPro"
"The digital orthophotos fully comply with NMAS standards
for production of orthophotos at a horizontal natural
ratio of 1 to 2,400 with a ground pixel resolution of 1 foot."
"The digital elevation model is fully compliant with National
Standard for Spatial Data Accuracy (NSSDA) published by
the Federal Geographic Data Committee (FGDC) in 1998.
The NSSDA uses root-mean-square error (RMSE) to
estimate positional accuracy. RMSE is the square root of
the average of the set of squared differences between
data set coordinate values and coordinate values from an
independent source of higher accuracy for identical points.
Accuracy is reported in ground distances at the 95%
confidence level. Accuracy reported at the 95%
confidence level means that 95% of the positions in the
data set will have an error with respect to true ground
position that is equal to or smaller than the reported
accuracy value. The reported accuracy value reflects all
uncertainties, including those introduced by geodetic
control coordinates, compilation, and final computation of
ground coordinate values in the product."
Kevin J. Chappell
20040421
Report of Survey - SWFWMD, Sarasota County, FL
diagram
1200
electronic mail system
20040720
ground condition
Ground Control
"Kevin Chappell, a Florida PSM, under contract to
EarthData International established 15 photo identifiable
ground control after aerial imagery acquisition. The points
were surveyed using GPS for both vertical and horizontal
coordinate values. Ground control references Florida
West State Plane NAD83, NAVD88 both in Meters."
EarthData Aviation, LLC
20040208
Digital Aerial Photography of Sarasota County, FL
profile
14,400
Firewire Drive
20040203
20040208
Ground Condition
Digital Aerial Photography
The digital aerial photographic mission was composed of a
total of 2 lifts of flight lines. Photography was obtained at
an altitude of 9,450 feet above mean terrain. Digital
photography was recorded in conjunction with airborne
GPS; the stationary GPS receiver was positioned over a
control point located at the airport. Recorded digital
imagery was shipped via external hard drive to the
production facility for processing.
EarthData Aviation
20040304
Lidar Acquisition of Sarasota County, FL
profile
Firewire Drive
20040228
20040304
publication date
Lidar Acquisition
"The lidar acquisition for Sarasota County consisted of 2 lifts
of flight lines acquired in 2 sorties using the Leica ALS40
sensor. The data was acquired at a flying height of 6,000
feet AMT with a scan rate of 13 Hz and a 25 degree field
of view. Approximately 3.04 billion raw lidar points were
collected at a nominal 2 meter post spacing."
"New ground control was established to control and orient
the photography, and included only photo-identifiable
features. The ground control network and airborne GPS
data was integrated into a rigid network through the
completion of a fully analytical bundle aerotriangulation
adjustment.
1. The digital aerial photo data was ingested into the
ISTAR processing system by uploading the data from
portable hard drives.
2. The coverage of the imagery was checked for gaps and
a directory tree structure for the project was established
on one of the workstations. This project was then
accessed by other workstations through the network. The
criteria used for establishment of the directory structure
and file naming conventions accessed through the
network avoids confusion or errors due to inconsistencies
in digital data. The project area was reviewed against
the client-approved boundary. The technician verified that
the datum and units of measurement for the supplied
control were consistent with the project requirements.
3. The photogrammetric technician performed an
automatic triangulation of the data using the ISTAR
processing system. The aerotriangulation adjustment
merged the airborne GPS, IMU, and ground control data
into a project-wide network. While ground control points
(GCPs) were used, reliance on the GPS-/IMU-derived
orientation parameters required significantly fewer GCPs
than are typically used in aerotriangulation. The adjustment
was performed for each sortie and then multiple sorties
were merged to produce a project-wide adjustment. The
aerotriangulation component of the ISTAR suite utilized the
airborne GPS as a separate control source and held the
IMU (Inertial Measurement Unit) parameters rigidly
7. The accuracy of the final solution was verified by
running the final adjustment, placing no constraints on any
quality control points. The RMSE values for these points
must fall within the tolerances above for the solution to be
acceptable.
Aerotriangulation
ISTAR
20040930
AT
ISTAR
EarthData International
Harold Rempel
Senior Project Manager
mailing and physical address
7320 Executive Way
Frederick
Maryland
21704
301-948-8550
metadata@earthdata.com
"EarthData has developed a unique method for processing
lidar data to identify and remove elevation points falling
on vegetation, buildings, and other aboveground
structures. The algorithms for filtering data were utilized
within EarthData's proprietary software and commercial
software written by TerraSolid. This software suite of tools
provides efficient processing for small to large-scale,
projects and has been incorporated into ISO 9001
compliant production work flows. The following is a
step-by-step breakdown of the process.
1. Using the lidar data set provided by EarthData, the
technician performs calibrations on the data set.
2. Using the lidar data set provided by EarthData, the
technician performed a visual inspection of the data to
verify that the flight lines overlap correctly. The technician
also verified that there were no voids, and that the data
covered the project limits. The technician then selected a
series of areas from the data set and inspected them
where adjacent flight lines overlapped. These overlapping
areas were merged and a process which utilizes 3-D
Analyst and EarthData's proprietary software was run to
detect and color code the differences in elevation values
and profiles. The technician reviewed these plots and
located the areas that contained systematic errors or
distortions that were introduced by the lidar sensor.
3. Systematic distortions highlighted in step 2 were
removed and the data was re-inspected. Corrections
and adjustments can involve the application of angular
deflection or compensation for curvature of the ground
surface that can be introduced by crossing from one type
of land cover to another.
4. The lidar data for each flight line was trimmed in batch
for the removal of the overlap areas between flight lines.
The data was checked against a control network to
ensure that vertical requirements were maintained.
Conversion to the client-specified datum and projections
were then completed. The lidar flight line data sets were
then segmented into adjoining tiles for batch processing
and data management.
5. The initial batch-processing run removed 95% of points
falling on vegetation. The algorithm also removed the
points that fell on the edge of hard features such as
structures, elevated roadways and bridges.
6. The operator interactively processed the data
using lidar editing tools. During this final phase the
operator generated a TIN based on a desired thematic
layers to evaluate the automated classification performed
in step 5. This allowed the operator to quickly re-classify
points from one layer to another and recreate the TIN
surface to see the effects of edits. Geo-referenced images
were toggled on or off to aid the operator in identifying
problem areas. The data was also examined with an
automated profiling tool to aid the operator in the
reclassification.
6.The data were separated into a bare-earth DEM. A
grid-fill program was used to fill data voids caused by
reflective objects such as buildings and vegetation. The
final DEM was written to an ASCII XYZ and LAS format.
7. The reflective surface data were also delivered in ASCII
XYZ and LAS format.
8. Final TIN files are created and delivered."
lidar
20040817
lidar
Harold Rempel
EarthData International
Senior Project Manager
mailing and physical address
7320 Executive Way
Frederick
Maryland
21704
USA
301-948-8550
metadata@earthdata.com
"This process describes the method used to compile
hydro-breaklines to support H&H modeling efforts. The
technical method used to produce hydro-breaklines for use
in this project only included water features and they should
not be confused with traditional stereo-graphic or field
survey derived breaklines. Watershed Concepts and
EarthData utilized techniques developed for FEMA
floodmap modernization projects to synthesize 3D break
lines using digital orthophotos and lidar data.
1. For larger streams (widths greater than 50 feet),
breaklines were collected on the left and right water edge
lines. The 2D lines defining streams and other water
bodies were manually digitized into ArcView shape file
format from the ADS-40 digital imagery. Flat water bodies
such as ponds were collected. by examining points near
the edge of water, were a low point could be quickly
identified. This allowed the operators to draw an
even-elevation breakline at that elevation around the
water body's perimeter.
2. A bounding polygon, created from the edge of bank
lines, was used to remove all lidar points from within the
channels of streams and bodies of water. This step
ensures that the lidar bare-earth point files match the
breaklines.
3. The elevation component of the 3D streamlines
(breaklines) was derived from the lowest adjacent bare
earth lidar point and was adjusted to ensure that the
streams flow downstream. The best elevation that can be
derived for the 3D streamlines will be the water surface
elevation on the date that the lidar data was acquired.
4. Automatic processes assigned elevations to the vertices
of the centerline based on surrounding lidar points. The
lines were then smoothed to ensure a continuous downhill
flow. Edge-of-bank vertices were adjusted vertically to
match the stream centerline vertices.
5. The new 3D lines were then viewed in profile to correct
any anomalous vertices or remove errant points from the
lidar DTM, which cause unrealistic "spikes" or "dips" in
the breaklines.
6. For this project, hydro breaklines were generated in the
matter described above for all streams and water bodies.
a) A
2000 to identify
any quality issues. b) An automated routine was run to
check the data for closure of water bodies. c) An
evaporation routine was run to remove lidar points from
water bodies. d) A final routine was run to check the
generate TINs for anomalies including outside
township/range boundary and elevation extremes.
8.New TINs were then created from the remaining lidar
points and newly created breaklines.
9. The breakline data set was then put into an ESRI shape
file format
10. The 1 foot contours were generated in
Microstation (using 2 foot specifications) with an overlay
software package called TerraSolid. Within TerraSolid, the
module Terramodler was utilized to first create the tin and
then a color relief was created to view for any irregularities
before the contour generator was run. The contours were
checked for accuracy over the DTM and then the Index
contours were annotated. At this point the technician
identified any areas of heavy tree coverage by collecting
obscure shapes. Any contours that were found within
these shapes are coded as obscure. The data set was
viewed over the orthos before the final conversion. The
contours were then converted to Arc/Info where final QC
AMLs were run to verify that no contours were crossing.
The contours were delivered in ESRI .shp format as a
merged file.
<<Due to the nature of the breaklines collected in
accordance with FEMA guidelines, the contours do not
meet any specified accuracy requirement and are
delivered as is.>>"
Breaklines
Contours
20050415
Breaklines
Contours
EarthData International
Harold Rempel
Senior Project Manager
mailing and physical address
7320 Executive Way
Frederick
Maryland
21704
301-948-8550
"The digital orthophotography was produced in natural color
at a natural ratio of 1 to 2,400 with a 1 ft pixel resolution. A
step-by-step breakdown of the digital orthophoto
production process follows.
1. Digital image swath files were visually checked for
image quality on the networked ISTAR processing farm.
2. The digital image files were loaded onto the digital
orthophoto production workstation. The following
information was then loaded onto the workstation.
- The camera parameters and flight line direction
- Ground control and pass point locations
- The exterior orientation parameters from the
aerotriangulation process
- ASCII file containing the corner coordinates of the
orthophotos
- The digital elevation model.
- Project-specific requirements such as final tile size
and resolution.
-Orientation parameters developed from the
aerotriangulation solution.
A coordinate transformation based on the camera
calibration fiducial coordinates was then undertaken. This
transformation allowed the conversion of every measured
element of the images to a sample/line location. Each pixel
in an image was then referenced by sample and line (its
horizontal and vertical position) and matched to project
control.
3. The newly re-sected image was visually checked for
pixel drop-out and/or other artifacts that may degrade the
final orthophoto image.
4. DTM data were imported and written to the correct
subdirectory on disk.
5. The DTM file was re-inspected for missing or erroneous
data points.
6. A complete differential rectification was carried out
using a cubic convolution algorithm that removed image
displacement due to topographic relief, tip and tilt of the
aircraft at the moment of exposure, and radial distortion
within the camera. Each final orthophoto was produced at
a natural scale of 1 to 2,400 with a 1ft pixel
resolution. At this point in the process, the digital
orthophotos covered the full aerial frame.
7. Each digital orthophoto image was visually checked
for accuracy on the workstation screen. Selected control
points (control panels or photo-identifiable points) that are
visible on the original film were visited on the screen, and
the X and Y coordinates of the location of the panel or
photo-identifiable point were measured. This information
was cross-referenced with the X and Y information
provided by the original ground survey. If the orthophoto
did not meet or exceed NMAS standards, the
rectification was regenerated. The digital orthophotos were
then edge-matched using proprietary software that runs in
Z/I Imaging OrthoPro software package. Adjoining images
were displayed in alternating colors of red and cyan. In
areas of exact overlap, the image appears in gray-scale
rendition. Offsets were colored red or cyan, depending on
the angle of displacement. The operator panned down
each overlap line at a map scale to inspect the overlap
area. Any offset exceeding accuracy standards was
re-rectified after the DTM and AT information was
rechecked.
8. Once the orthos were inspected and approved for
accuracy, the files were copied to the network and
downloaded by the ortho finishing department. This
production unit was charged with radiometrically correcting
the orthophotos prior to completing the mosaicking and
clipping of the final tiles. The image processing technician
performed a histogram analysis of several images that
contained different land forms (urban, agricultural, forested,
etc.) and established a histogram that best preserves detail
in highlight and shadow areas. EarthData International
has developed a proprietary piece of software called
"Image Dodging." This radiometric correction algorithm
was utilized in batch and interactive modes. Used in this
fashion, this routine eliminated density changes due to sun
angle and changes in flight direction. A block of images
were processed through image dodging, in batch mode
and displayed using Z/I Imaging OrthoPro software. At this
point the images have been balanced internally, but there
are global differences in color and brightness that were
adjusted interactively. The technician assigned correction
values for each orthophoto then displayed the corrected
files to assess the effectiveness of the adjustment. This
process was repeated until the match was considered near
seamless. The files then were returned to digital
orthophoto production to mosaic the images.
9. The processed images were mosaicked using the Z/I
Imaging software. The mosaic lines were set up
interactively by the technician and were placed in areas
that avoided buildings, bridges, elevated roadways, or
other features that would highlight the mosaic lines. File
names were assigned.
10. The finishing department performed final visual checks
for orthophoto image quality. The images were inspected
using Adobe Photoshop, which enabled the technician to
remove dust and lint from the image files interactively.
Depending on the size and location of the flaw, Photoshop
provided several tools to remove the flaw. Interactive
removal of dust were accomplished at high magnification
so that repairs are invisible.
11. The final orthophoto images were written out into
GeoTIFF format."
Digital Orthophotos
20040915
Orthos
EarthData International
Harold Rempel
Senior Project Manager
mailing and physical address
7320 Executive Way
Frederick
Maryland
21704
301-948-8550
metadata@earthdata.com
The metadata were imported and updated for display through the Seamless Data Distribution System at <http://seamless.usgs.gov>
200705
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)
0
Point
State Plane Coordinate System 1983
0902
.9999411765
-024.333300
+82.000000
200000
0.00
coordinate pair
1.0
1.0
survey feet
North American Datum of 1983
Geodetic Reference System 80
6378137.00
0.2982572221010
North American Vertical Datum of 1988
.65
Feet
Explicit elevation coordinate included with horizontal coordinates
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
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.
2007
unknown
20070529
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