napa_nws_mapping.met
napa_nws_mapping.met
Identification_Information:
Citation:
Citation_Information:
Originator: Towill, Inc.
Publication_Date: Unknown
Publication_Time: Unknown
Title: Napa County and Valley Watershed Mapping
Edition: 1
Geospatial_Data_Presentation_Form: map
Publication_Information:
Publication_Place: Napa County, CA
Publisher: Information Technology Services Department
Other_Citation_Details:
1) Aerial Photo Acquisition
2) Aerotriangulation
3) Photogrammetric Compilation of DTM
4) Generation of Contour Maps
5) Generation of Digital Orthophotos
Description:
Abstract:
1) Aerial Photo Acquisition
2) Aerotriangulation
3) Photogrammetric Compilation of DTM
4) Generation of Contour Maps
5) Generation of Digital Orthophotos
The entire of Napa County was mapped during this project.
However, two major areas were designated as Watershed
and Non-Watershed and employed differing techniques for
development of the final map data. The major difference
was that the Watershed used LiDAR data for development
of the DTM and the Non-Watershed relied on
photogrammetric development of the DTM.
The County and WS/NWS boundaries were provided by the
Napa County PM in ESRI shapefile format. A buffer
was applied to the County boundary line to ensure full
coverage within Napa County.
Purpose:
1) Develop DTMs for the Watershed and Non-Watershed
regions.
2) Develop Contour Maps for the Watershed and Non-
Watershed regions.
3) Develop Digital Orthophoto Maps for the Watershed
and Non-Watershed regions.
Supplemental_Information:
Note that there are two owners of the final map data. Both
the Napa County, CA Information Technology Services Department
Department and the U.S. Army Corps of Engineers, San
Francisco District have been provided a complete set of all
project deliverables.
Additional information or associated products may be
available from these sources.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20020422
Ending_Date: 20020423
Currentness_Reference: Ground Condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: Unknown
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -122.65555555
East_Bounding_Coordinate: -122.05027777
North_Bounding_Coordinate: 38.87194444
South_Bounding_Coordinate: 38.31333333
Keywords:
Theme:
Theme_Keyword_Thesaurus: Tri - Service Spatial Data Standard
Theme_Keyword: Geodetic/Cadastral
Place:
Place_Keyword_Thesaurus: Geographic Names Information System
Place_Keyword: Napa County, California
Access_Constraints: unknown
Use_Constraints: Intended for planning level usage.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Towill, Inc.
Contact_Address:
Address_Type: mailing and physical address
Address: 444 Natoma St.
City: San Francisco
State_or_Province: California
Postal_Code: 94103
Country: USA
Contact_Voice_Telephone: (415) 243-4384
Hours_of_Service: 8am - 5pm (Pacific)
Contact_Instructions:
Technical Information may be obtained through the
Project Manager or the Vice President of Photogrammetry.
Native_Data_Set_Environment:
DTM data were provided in AutoCad v15 and ArcView 3.x
formats.
Topo data were provided in AutoCad v15 and ArcView 3.x
formats.
Orthophoto data were provided in TIFF and MrSid formats.
Survey and Aerotriangulation reports were provided in
paper and digital files, including MS Word, MS Excel,
Adobe PDF and ASCII formats.
All new map data were partitioned into 12,000 by 12,000
feet tiles for delivery. A tile index map is available
in both AutoCad v15 and ESRI Shapefile formats. A total
of 94 mapping tiles were generated within the Non-Watershed
region.
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
DTM data were photogrammetrically collected using
procedures intended to meet sufficient density and
accuracy for derivation of ten (10) feet contours which
meet NMAS. In areas where dense vegetation or other
features obscure the ground, height data may deviate from
its correct elevation and may not be considered reliable
without further verification.
Topographic maps were generated with procedures
intended to meet NMAS for 10 feet contours and spot
heights.
Orthophoto Maps (with 1 foot pixels) were generated with
procedures intended to meet NMAS for 1:4,800 scale
mapping.
Logical_Consistency_Report:
Both, this metadata file "napa_nws_mapping" and
metadata file "napa_ws_mapping", refer to the same
overall mapping project for Napa County.
Note that this project was sponsored jointly by the Napa
County ITS and the U.S. Army Corps of Engineers - San
Francisco District, and all data have been duplicately
delivered and accepted by both parties.
Completeness_Report:
This metadata file is intended to provide general
information related to the production of the project mapping
deliverables. Additional details may be available in the
reports cited and by contacting the data provider POC
and/or the data production POC.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
DTM - Measured points are expected to be around +/- 2.5
feet, depending on the feature being measured.
Contours & Spots - Expected to meet NMAS standards
for 1:4,800 scale topgraphic mapping.
Orthophotos - Expected to meet NMAS horizontal standards
for 1:4,800 scale orthophoto mapping.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
DTM - Measured points are expected to be around +/- 2.5
feet, depending on the feature being measured.
Contours & Spots - Expected to meet NMAS vertical
accuracy for 10 foot contour mapping with a map scale
of 1:4,800.
Orthophotos - Not Applicable.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator: Towill, Inc.(comp.)
Publication_Date: Unpublished material
Publication_Time: Unknown
Title: Aerial Photo Control Survey
Edition: 1
Geospatial_Data_Presentation_Form: model
Other_Citation_Details:
A detailed survey report, including a final control listing,
network adjustment statistics, field notes, etc. was
generated for this project and may be obtainable by
contacting the data distribution Point of Contact.
Source_Scale_Denominator: NA
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 20021203
Source_Currentness_Reference: Publication Date
Source_Citation_Abbreviation: GPS Photo Control Survey
Source_Contribution:
Photo Control Survey was used to establish the ground ties
to the aerial photography.
The Survey methods used were intended to provide aerial
target locations within the specifications necessary to
produce 1:2,400 mapping with 5 & 10 ft. contours.
Source_Information:
Source_Citation:
Citation_Information:
Originator: Towill, Inc.
Publication_Date: Unpublished material
Publication_Time: Unknown
Title: Analytical Aerotriangulation
Edition: 1
Geospatial_Data_Presentation_Form: model
Other_Citation_Details:
A detailed A/T report, including a narrative, flight design
graphic, final pass/tie point listing, and least squares
adjustment statistics was generated for this project and
may be obtainable by contacting the data distribution Point
of Contact.
Source_Scale_Denominator: NA
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 20021121
Source_Currentness_Reference: Publication Date
Source_Citation_Abbreviation: Analytical Aerotriangulation
Source_Contribution:
For the main portion of the project, Airborne GPS was used
as the primary aerotriangulation control by construction of
the exposure center location and supplemented with a
sparse network of ground photo control. For areas that protruded
from the main photo block, additional ground control was
employed. GrafNav v.6.03a software was used to reduce
the GPS data and derive the photo center coordinates.
Aerial photography negatives were scanned at 12.5
microns on a Vexcel Imaging VX4000 scanner and
photo pass/tie and ground control point mensuration was
performed using a Leica SocetSet softcopy stereo plotter.
Final aerotriangulation adjustments were derived using
ISBBA software and then translated back to Leica
SocetSet format for the purpose of stereo compilation.
Source_Information:
Source_Citation:
Citation_Information:
Originator: Air Flight Services
Publication_Date: Unpublished material
Publication_Time: Unknown
Title: Aerial Photography
Edition: 1
Geospatial_Data_Presentation_Form: view
Other_Citation_Details:
Natural color aerial photography was flown nominally
12,000 ft. above the terrain using a WILD RC-30 camera with
lens serial number 13302. The aircraft used was a Cessna
210, tail number N6278C, equipped with a GPS antenna
mounted at coordinates –0.14, -0.03, 1.301 (x,y,z
coordinates in meters measured from the entrance pupil of
the camera to the base of the antenna). Four hundred
seventy-one (471) exposures were obtained on April 22,
2002 and April 23, 2002. The original aerial negatives were
scanned at 12.5 microns using a Vexcel Imaging
VX4000 scanner.
Two GPS receivers (Ashtech and NovaTel) collected
position data and camera event data in the aircraft, and
three local GPS base stations were established and
utilized, for this project. Comparison of the GPS solutions,
using combinations of airborne receivers and ground base
stations, demonstrated the solution differences to be within
expected tolerances. The final solutions for this project use
the Ashtech Z12 receiver in the aircraft and a Trimble
4700 receiver, with Compact L1/L2 antenna mounted on a
2m fixed height tripod, occupying our base station at
Primary Airport Control Station APC-D, located at Napa
County Airport. All GPS receivers were set to record
measurements at 1 second (1 Hz) epochs.
The primary mapping photography was flown as a block
with parallel flights flown in the NW/SE direction. Flight
lines 18 and 19 were flown in specific directions to cover
protrusions from the primary block. Flight lines 14, 15, 16,
and 17 were flown as cross-flights at the ends of and
perpendicular to the primary block in order to strengthen
the computations.
Source_Scale_Denominator: 24000
Type_of_Source_Media: filmstrip
Source_Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 20020422
Ending_Date: 20020423
Source_Currentness_Reference: Ground Condition
Source_Citation_Abbreviation: Aerial Photography
Source_Contribution:
Aerial photography acquired for the Napa County
Watershed and Valley mapping project is being stored in
the original negative film format. Access to this film is
limited to client authorized personnel or agencies.
Both the USACE and Napa County have a set of contact
prints that were produced from the original film. Note that
this reproduction does not include photography from the
cross flights, which were used only for development of the
aerotriangulation block and are considered redundant
imagery.
The aerial photography was used for the following
1) Direct stereo compilation of the digital terrain model
(DTM) data.
2) Derivation of digital orthophoto imagery.
Process_Step:
Process_Description:
The Non-Watershed DTM was derived
photogrammetrically from the April, 2002 aerial
photography. Leica SocetSet software, v. 4.02, was used
to compile directly from the stereo imagery into an AutoCad
3-dimensional files. Breaklines and masspoints were
digitized by an operator viewing the imagery and new
vector data (in real-time 3D), with the assistance of real-time
approximate contours superimposed on the stereo
imagery.
Data were collected to correspond with significant
changes in the terrain and with sufficient density that direct
height information was measured approximately every 400
feet to 800 feet. Additional measurements were made to
help represent significant features, such as the top and toe
of a levee and visible hilltops.
As with all photo derived map data, areas that contain
heavy vegetation, or other features that obscure the
ground, height measurements may be considered only
approximate.
Source_Used_Citation_Abbreviation: Aerial Photography
Source_Used_Citation_Abbreviation: Aerotriangulation - AT
Process_Date: 20031000
Source_Produced_Citation_Abbreviation: Digital Terrain Model - DTM
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Towill, Inc.
Contact_Address:
Address_Type: mailing and physical address
Address: 444 Natoma St.
City: San Francisco
State_or_Province: California
Postal_Code: 94103
Country: USA
Contact_Voice_Telephone: (415) 243-4384
Hours_of_Service: Business Hours
Process_Step:
Process_Description:
The Non-Watershed contour mapping was derived by
algorithmic interpolation of the DTM, using TerraModel v.9.6
software. Some line smoothing and manual
displacement of contours was performed to enhance the
cartographic expression of the representative data.
Spot heights were placed in strategic locations, using the
available DTM points, which may include a masspoint or a
vertex of a breakline.
Source_Used_Citation_Abbreviation: Digital Terrain Model - DTM
Process_Date: 20031000
Source_Produced_Citation_Abbreviation: 10 Foot Topographic Mapping
Process_Step:
Process_Description:
The Non-Watershed color orthophoto mapping was
derived by
rectifying ground relief displacements, using the
photogrammetric DTM and scanned aerial photography (as
described in the preceding process steps). Leica Socet
-Set software, v. 4.02, was used for the orthorectification
and tile output process. The file format of the SocetSet
orthophoto output was 24-bit TIFF.
Further adjustments were made to the orthophoto imagery
to improve the overall color balance, blend mosaic edges
and remove minor blemishes. These efforts were
performed using Adobe Photoshop software.
MrSid files were generated for each tile (no project wide
mosaic was created) using the finalized orthophoto TIFF
and world (TFW) files. For this process, the compression
ratio was set at 30 to 1 and the background color (to be used
as null pixels) was set to black (0,0,0 [r,g,b]).
Source_Used_Citation_Abbreviation: Digital Terrain Model - DTM
Source_Used_Citation_Abbreviation: Aerial Photography
Process_Date: 20031000
Source_Produced_Citation_Abbreviation: Color Digital Orthophoto Mapping
Cloud_Cover: 0
Spatial_Data_Organization_Information:
Indirect_Spatial_Reference:
All data were partitioned into 12,000 by 12,000 feet tiles for
delivery. A tile index map is available in both AutoCad v15
and ESRI Shapefile formats.
The following list describes the general data
DTM Data
AutoCad - File contains breaklines and masspoints on
separate layers.
ESRI Shapefile - Independent themes are used for
breakline and masspoint data.
Topo Data
AutoCad - File contains contours, spot heights and labels.
Contour attributes, such as index or depression, are
indicated by use of separate layers.
ESRI Shapefile - Independent themes are used for
contours and elevation data. No labels are provided for
this data format.
Orthophoto Data
TIFF - All tiles are the same size and areas outside of the
project limit are represented with black (0,0,0) pixel values.
These files include projection header information (GeoTIFF
format) and an associated world (.TFW) geo-referencing
file.
MrSid - Each individual TIFF tile was independently
converted to MrSid format (no mosaicing occurred) using a
compression ration of 20:1 and a background color of black.
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: State Plane Coordinate System 1983
State_Plane_Coordinate_System:
SPCS_Zone_Identifier: 0402
Lambert_Conformal_Conic:
Standard_Parallel: 38.333333
Standard_Parallel: 39.833333
Longitude_of_Central_Meridian: +122.000000
Latitude_of_Projection_Origin: +39.800000
False_Easting: 6561666.6666
False_Northing: 1640416.6666
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: distance and bearing
Distance_and_Bearing_Representation:
Distance_Resolution: 1
Bearing_Resolution: 1
Bearing_Units: Decimal degrees
Bearing_Reference_Direction: North
Bearing_Reference_Meridian: Grid
Planar_Distance_Units: Survey Feet
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: Geodetic Reference System 80
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257222101000020000
Vertical_Coordinate_System_Definition:
Altitude_System_Definition:
Altitude_Datum_Name: North American Vertical Datum of 1988
Altitude_Resolution: 1
Altitude_Distance_Units: Feet
Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates
Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: NA
Entity_Type_Definition: NA
Entity_Type_Definition_Source: NA
Overview_Description:
Entity_and_Attribute_Overview: NA
Entity_and_Attribute_Detail_Citation: NA
Metadata_Reference_Information:
Metadata_Date: 20040500
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Napa County, CA - IT Services
Contact_Address:
Address_Type: mailing and physical address
Address: 650 Imperial Way, Suite 201
City: Napa
State_or_Province: California
Postal_Code: 94559
Country: USA
Contact_Voice_Telephone: (707) 259-8141
Contact_Instructions: Contact in regard to distribution and general usage.
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: Corpsmet 1.3