Digital Contours

Metadata: 2000 Digital 2’ Contours and Digital Terrain Model, Washington County, Minnesota

2000 Digital 2’ Contours and Digital Terrain Model, Washington County, Minnesota

This page last updated: 03/2002
Metadata created using Minnesota Geographic Metadata Guidelines

Metadata Summary

Originator Washington County Survey and Land Management Division
Abstract This data set contains 2-foot contours, digital terrain model data, and basic planimetric features covering Washington County, Minnesota. The coverage extends a minimum distance of 400 feet outside the County’s boundary in areas where the County boundary is not determined by the St. Croix River or the Mississippi River. Aerial photography, at a scale of 1” = 833’, was gathered at 5000 feet during 3 separate flights during the month of April, 2000 to support the creation of this data set. The data is provided in Public Land Survey System section tiles that edge-match with neighboring tiles. The data is available on CD-ROM in AutoCAD drawing file format or Arc/Info coverage format, (contour and spot elevation data only). All data is in Washington County Coordinate System NAD83 coordinates. Complete project specifications are available for review.



The data set was compiled over an 18 month period of time and was delivered by the contractor to Washington County in increments. The data was subjected to quality control procedures by the county and when the determination was made that project standards had been satisfied the data was made available for distribution.
Browse Graphic None available
Time Period of Content Date 04/2000
Currentness Reference
Access Constraints Subject to license agreement with Washington County. Contact the Washington County Survey and Land Management Division for data pricing schedule.
Use Constraints Subject to license agreement with Washington County.
Distributor Organization Washington County Survey and Land Management Division
Ordering Instructions Contact: Washington County Survey and Land Management Division

(651) 430-6875
Online Linkage None available

Full Metadata

2000 Digital 2’ Contours and Digital Terrain Model, Washington County, Minnesota

Go to Section:
1. Identification Information
2. Data Quality Information
3. Spatial Data Organization Information
4. Spatial Reference Information
5. Entity and Attribute Information
6. Distribution Information
7. Metadata Reference Information

Section 1 Identification Information
Top of page
Originator Washington County Survey and Land Management Division
Title 2000 Digital 2’ Contours and Digital Terrain Model, Washington County, Minnesota
Abstract This data set contains 2-foot contours, digital terrain model data, and basic planimetric features covering Washington County, Minnesota. The coverage extends a minimum distance of 400 feet outside the County’s boundary in areas where the County boundary is not determined by the St. Croix River or the Mississippi River. Aerial photography, at a scale of 1” = 833’, was gathered at 5000 feet during 3 separate flights during the month of April, 2000 to support the creation of this data set. The data is provided in Public Land Survey System section tiles that edge-match with neighboring tiles. The data is available on CD-ROM in AutoCAD drawing file format or Arc/Info coverage format, (contour and spot elevation data only). All data is in Washington County Coordinate System NAD83 coordinates. Complete project specifications are available for review.

The data set was compiled over an 18 month period of time and was delivered by the contractor to Washington County in increments. The data was subjected to quality control procedures by the county and when the determination was made that project standards had been satisfied the data was made available for distribution.
Purpose Uses of the digital 2 foot contours, digital terrain model data, and basic planimetric features within Washington County include: creation of preliminary grading plans, hydrologic analysis, land use planning, zoning enforcement, law enforcement applications, surface water analysis, flood plain management, road design, and the updating of GIS parcel base mapping.
Time Period of Content Date 04/2000
Currentness Reference
Progress Complete
Maintenance and Update Frequency Unknown
Spatial Extent of Data All of Washington County, including a buffer that extends a minimum distance of 400 feet outside the County’s boundary in areas where the county boundary is not determined by the St. Croix River or the Mississippi River.
Bounding Coordinates


Place Keywords
Theme Keywords Contours, topography, DTM, digital terrain model, planimetric, elevation
Theme Keyword Thesaurus
Access Constraints Subject to license agreement with Washington County. Contact the Washington County Survey and Land Management Division for data pricing schedule.
Use Constraints Subject to license agreement with Washington County.
Contact Person Information John Baer, Survey Project Coordinator
Washington County Survey and Land Management Division
14949 62nd Street North P.O. Box 6
Stillwater, MN 55082
Phone: 651-430-6883
FAX: 651-430-6888
E-mail: john.baer@co.washington.mn.us
Browse Graphic None available
Browse Graphic File Description
Associated Data Sets 2000 Digital Orthophotos, Washington County, Minnesota


Section 2 Data Quality Information Top of full metadata Top of page
Attribute Accuracy The only attributes with a numeric value of significance to the data set are those attributes containing elevation values. Please see “Vertical Positional Accuracy” below.
Logical Consistency All polyline features, (AutoCAD), and all arc features, (Arc/Info), are clipped at the section tile boundary and edge-match with corresponding features on adjoining section tiles.
Completeness 36 PLSS sections located in Township 32 North, Range 21 West, Forest Lake, MN



36 PLSS sections located in Township 32 North, Range 20 West, New Scandia Township, MN



6 PLSS sections located in Township 32 North, Range 19 West, New Scandia Township, MN



36 PLSS sections located in Township 31 North, Range 21 West, Hugo, MN



36 PLSS sections located in Township 31 North, Range 20 West, Marine on St. Croix and May Township, MN



10 PLSS sections located in Township 31 North, Range 19 West, Marine on St. Croix and May Township, MN



36 PLSS sections located in Township 30 North, Range 21 West, Mahtomedi, Dellwood, Willernie and Grant, MN



29 PLSS sections located in Township 30 North, Range 20 West, City of Stillwater, Stillwater Township and Oak Park Heights, MN



36 PLSS sections located in Township 29 North, Range 21 West, Lake Elmo and Oakdale, MN



31 PLSS sections located in Township 29 North, Range 20 West, Bayport, Oak Park Heights, Baytown, Lakeland, Baytown Township, and West Lakeland Township, MN



30 PLSS sections located in Township 28 North, Range 20 West, Afton, Lakeland Shores, Lake St. Croix Beach, and St. Mary’s Point, MN



36 PLSS sections located in Township 28 North, Range 21 West, Woodbury, MN



4 PLSS sections located in Township 28 North, Range 22 West, Newport, MN



28 PLSS sections located in Township 27 North, Range 20 West, Denmark Township, MN



36 PLSS sections located in Township 27 North, Range 21 West, Cottage Grove, MN



12 PLSS sections located in Township 27 North, Range 22 West, St. Paul Park & Grey Cloud Island Twp., MN



6 PLSS sections located in Township 26 North, Range 20 West, Denmark Township, MN



7 PLSS sections located in Township 26 North, Range 21 West, Cottage Grove and Denmark Township, MN



2 PLSS sections located in Township 26 North, Range 22 West, Cottage Grove, MN
Horizontal Positional Accuracy 795 identifiable features, selected at random from the planimetric objects within the data set, were compared with RTK GPS field measurements of the same points. Using the National Standard for Spatial Data Accuracy, the data set tested as follows:

1.5 feet horizontal accuracy at 95% confidence level for the X coordinate value.

1.5 feet horizontal accuracy at 95% confidence level for the Y coordinate value.
Vertical Positional Accuracy 865 spot elevations, on a hard surface and selected at random from the data set, were compared with RTK GPS field measurements of the same points. Using the National Standard for Spatial Data Accuracy, the data set tested as follows:

1.2 feet vertical accuracy at 95% confidence level for the Z coordinate value.
Lineage This data set was developed under a contract with GRW Aerial Surveys, Inc., Lexington, Kentucky.

Limited planimetric features with 2-foot contours and digital terrain model for Washington County, MN were developed under contract with GRW Aerial Surveys, Inc.

The Contractor acquired new vertical black and white aerial photography at a photo scale of 1”=833’ (1:9996 scale or at an altitude of 5,000 ft.). There were 35 flight lines, 1211 exposures, 1101 exposures used for aerotriangulation (AT), 60% forward overlap and 30% sidelap flown in a north/south direction along PLS section centerlines utilizing a CCNS-4 flight management system. Lines 1 thru 17 were flown on 4-6-00, Lines 19 and 26 thru 35 were flown on 4-21-00, Lines 18 and 20 thru 25 were flown on 4-22-00. The contractor flew the project utilizing a twin engine Cessna T310R turbo-charged aircraft and a Zeiss 15/23 TOP Camera with forward motion compensation and gyro-stabilized mount.

The contractor acquired airborne GPS data using two Trimble 4000SSI ground base units and one Trimble 4000SSI unit located in the aircraft during the photo acquisition flight. Final airborne GPS data was processed using Fly-Kin software. The airborne photo center coordinate data was used as input to the AT solution.

The contractor scanned each film diapositive at a scan resolution of 12 microns to yield a .39’ ground resolution pixel size. During the orthophoto rectification process the pixels were resampled to a ground resolution of .5’. TIFF images were exported for use in the softcopy workstation during data collection process and digital orthophoto production.

A Fully Analytical Aerotriangulation Solution for the entire photo block was developed for use during the data collection and orthophoto production phases. Each diapositive was pugged using a PUG-4 point transfer instrument and then each pug was accurately measured using an Intergraph IMA Stereoplotter. This process connects photo to photo along the flight line with pugs called pass points and connects photos to photos from flight line to adjacent flight line with pugs called tie points. Once the measuring of each pug was completed, a software analysis determined in a local coordinate system of microns how well everything fit. Ground Control and Airborne GPS data was then introduced and a transformation from local system of microns to ground units of feet took place. This then allowed the control network to extend across multiple photos, verified the ground control network and provided independent data of the project ground check points for verification. The final AT solution used for the mapping of this project was produced utilizing Bingo Software. As an independent quality control measure the contractor also produced an AT solution utilizing Albany Software, compared the results and found them consistent.

The results of GRW’s AT solution for 443 identifiable ground target points were compared with coordinate positions determined by county survey personnel using Trimble real time kinematic, (RTK), GPS. Each target was occupied twice with RTK GPS and an X, Y, & Z coordinate was recorded. With the exception of 4 points, the difference between the X, Y, & Z values of the computed AT coordinate value and RTK GPS value was less than 1 foot.

The average of the differences in X, Y, & Z values between computed AT coordinate value and RTK GPS value, taking into account positive and negative signs are listed below:


X = -0.007 feet

Y = -0.004 feet

Z = 0.001 feet


The root mean square error, (RMSE), of the final block adjustment is listed below:


X = 0.304 feet

Y = 0.307 feet

Z = 0.161 feet


The Contractor used a combination of analytical (IMA’s, DSR-14’s interfaced with KORK Digital Mapping Software) and softcopy stereoplotters (ZI SSK’s interfaced with Microstation) to collect the mapping data. Planimetric and topographic data was delivered to an extent of 400’ beyond the County boundary.

Planimetric data delivered in AutoCad version 14 was: Road Edges (Urban and Rural), Paved Trails, Railroad Centerlines, Bridges, Major Culverts, Dam Structures, Rivers and Streams, Lakes and Ponds, and Towers (Water, Communication, Steel Electrical).

A digital terrain model, (DTM), was created using break lines along changes in slopes and a mass point grid of 50’ for areas requiring contours. The DTM and 2 ’ contours were delivered in AutoCad version 14 dwg format. The 2’ contours were also delivered in Arc/Info format.

Digital elevation model, (DEM), data was created using break lines along major changes in slopes and a mass point grid of 50’ for use in developing the orthophotos in areas not requiring contours.
Source Scale Denominator

Section 3 Spatial Data Organization Information Top of full metadata Top of page
Native Data Set Environment AutoCAD format. ArcGIS (contour and spot elevation data only)
Geographic Reference for Tabular Data Not applicable.
Spatial Object Type Vector
Vendor Specific Object Types ArcGIS points and arcs. AutoCAD points, polylines, and text.
Tiling Scheme Public Land Survey System section tiles

Section 4 Spatial Reference Information Top of full metadata Top of page
Horizontal Coordinate Scheme County Coordinates
Ellipsoid GRS80
Horizontal Datum NAD83 (96)
Horizontal Units Feet
Distance Resolution
Altitude Datum NAVD88
Altitude Units Feet
County Coordinate Zone Identifier 44
Map Projection Name Traverse Mercator
Map Projection Parameters False Northing in meters = 30481.2751
False Easting in meters = 152406.3759
Central Meridian = -92 50 00
Latitude of Grid Origin = 44 44 45
Grid Scale Factor
at Central Meridian = 1.000039836799
State Plane Zone = 4326
Other Coordinate System's Definition N/A

Section 5 Entity and Attribute Information Top of full metadata Top of page
Entity and Attribute Overview The Contour and Spot Elevation Data exists in two software formats, AutoCAD and Arc/Info. Planimetric Data and Digital Terrain Model Data, (DTM), is available in AutoCAD format only.

The Arc/Info coverages are contained in directories unique to each section tile. These directories are named with the letter “w” followed by 7 characters representing the Public Land Survey System (Section, Township, and Range). Each section tile has two Arc/Info coverages associated with it. An arc (line) coverage called “TOPO” represents contours with attached attribute data. A point coverage called “SPOT” contains point locations with attached elevation attribute data.

Each section tile has 3 AutoCAD drawing files associated with it. The first drawing file contains Contour and Spot Elevation data. Contours are depicted by unbroken polylines annotated with elevation text on all 10-foot contour intervals. Spot elevations are represented by point entities labeled with the point’s elevation. The second drawing file contains Digital Terrain Model, (DTM), data. This data includes both “hard” and “soft” breaklines represented by polylines. Mass points on a 50’ grid are also shown. The third drawing file contains basic planimetric features located from aerial photography. This data includes hydrologic features, transportation features, major culverts, and additional miscellaneous features. (See Layer Lists below).

The file naming convention indicates the section tile and type of data contained in the drawing. The first 7 characters of the drawing name represents the Public Land Survey System section: Township and Range followed by one of the following 3 letters:

“c” indicates that the drawing file contains contour-related data.

“d” indicates that the drawing file contains DTM data.

“p” indicates that the drawing file contains planimetric data.
Entity and Attribute Detailed Citation The two Arc/Info coverages and their associated attribute item names and values are listed below:

Coverage Name: TOPO

Feature Type: Arc

Starting Item

Column Name Width Output Type Decimal

1 FNODE# 4 5 B -

5 TNODE# 4 5 B -

9 LPOLY# 4 5 B -

13 RPOLY# 4 5 B -

17 LENGTH 8 18 F 5

25 TOPO# 4 5 B - -

29 TOPO-ID 4 5 B -

33 SYMBOL 3 3 I -

36 ELEV 4 4 I - -



Item name: SYMBOL

Value Description

0 Not yet coded

24 Index contour

25 Questionable index contour

26 Index depression contour

28 Intermediate contour

29 Questionable intermediate contour

30 Intermediate depression contour
31 Questionable intermediate depression contour
32 Index questionable depression

33 Index hidden questionable
34 Index hidden depression
126 Hidden for contour labels
127 Hidden contour

Item name: ELEV Contour Elevations

Coverage Name: SPOT

Feature Type: Point

Starting Item

Column Name Width Output Type Decimal

1 AREA 8 18 F 5 -

5 PERIMETER 8 18 F 5

9 SPOT# 4 5 B - -

13 SPOT-ID 4 5 B -

33 SYMBOL 3 3 I -

36 ELEV 4 12 F 1 -



Item name: SYMBOL

Value Description

23 Spot Elevation


Item name: ELEV Spot Elevations


The AutoCAD format files contain project data on unique layers. Below is a list of possible layers to be found on each of the three AutoCAD drawing files associated with a particular section tile.

“???????c”.dwg


Layer Name Feature Description

0

CONTROL Ground Control Points

SURROUND Section Tile Boundary

TO_02_CONT 2' Intermediate Contour

TO_02_DEP 2' Depression Contour

TO_02_QUES 2' Questionable Contour

TO_02_QUES_DEP 2' Questionable Depression Contour

TO_10_CONT 10' Index Contour

TO_10_DEP 10' Depression Contour

TO_10_HID_QUES 10’ Hidden Questionable Contour

TO_10_HIDDEN 10’ Hidden Contour

TO_10_QUES 10' Questionable Contour

TO_10_QUES_DEP 10' Questionable Depression Contour

TO_CON_LABEL Contour Elevation Label Text

TO_SPOT_ELEV Spot Elevation Point and Label Text

TO_LABEL_CONT 10’ Index Contour under Label Text


“???????d”.dwg



Layer Name Feature Description Block Name

0

DTM_SOFT Soft Breaklines

DTM_HARD Hard Breaklines

DTM_POINT DTM Masspoints MP





“???????p”.dwg



Layer Name Feature Description Block Name

0

CONTROL Ground Control Points HVCP

HY_CULVERT Culvert CU

HY_HEADWALL Headwall

HY_LAKE_POND Lake

HY_STREAM Stream or Ditch

SURROUND Section Tile Boundary

TO_WATER_ELEV Water Surface Elevation

TR_BRIDGE Bridge

TR_CURB_ROAD Curbed Road (face of curb)

TR_PAV_ROAD Paved Road (edge of pavement)

TR_RR_CENTER Railroad Centerline

TR_TRAIL Trail Centerline

TR_UNP_ROAD Unpaved Road (edge of gravel)

TX_FEATR_LABEL Feature Label

WATER_TOWER Water Tower W_TOWER

Section 6 Distribution Information Top of full metadata Top of page
Publisher Washington County Survey and Land Management Division
Publication Date 2002
Contact Person Information John Baer
Survey Project Coordinator
Washington County Survey and Land Management Division.
14949 62nd Street North P.O. Box 6
Stillwater, MN 55082
Phone: 651-430-6883
FAX: 651-430-6888
E-mail: John.baer@co.washington.mn.us
Distributor's Data Set Identifier Wash_contours2000.
Distribution Liability See Washington County License Agreement.
Transfer Format Name AutoCAD format. ArcGIS format
Transfer Format Version Number
Transfer Size AutoCAD format: Contour & spot elevation data: approx. 1 Mb per section tile. DTM data: approx. 1.5 Mb per section tile. Planimetric data: approx. 0.25 Mb per section tile AutoCAD format: Contour & spot elevation data: approx. 1 Mb per secti
Ordering Instructions Contact: Washington County Survey and Land Management Division

(651) 430-6875
Online Linkage None available

Section 7 Metadata Reference Information Top of full metadata Top of page
Metadata Date 03/2002
Contact Person Information John Baer, Survey Project Coordinator
Washington County Survey and Land Management Division
14949 62nd Street North P.O. Box 6
Stillwater, MN 55082
Phone: 651-430-6883
FAX: 651-430-6888
E-mail: John.baer@co.washington.mn.us
Metadata Standard Name Minnesota Geographic Metadata Guidelines
Metadata Standard Version 1.2
Metadata Standard Online Linkage http://www.lmic.state.mn.us/gc/stds/metadata.htm


This page last updated: 03/2002