National Urban Forest Conference

1
Wireless Forestry A Data Collection Model

• Presented by
• Chris Daniel
• Montgomery County Government
• Department of Information Systems and
  Telecommunications
• 110 N. Washington St, Suite 501
• Rockville, MD 20850
• chris.daniel_at_co.mo.md.us
• http//gis.co.mo.md.us

2
Acknowledgements

• Montgomery County, MD Government
• Lonnie Darr (Dept. of Environmental Protection)
• Jim Himel (Forester)
• Apollo Teng (GIS Manager, Dept. of Info. Systems
  and Telecommunications - Geographic Information
  Systems or DIST-GIS)
• Andrew Greene (GIS Intern, DIST-GIS)
• American Forests
• Gary Moll (Vice President of Urban Forestry)
• Ken Gorton (GIS Specialist)
• United States Forest Service (Northeast Forest
  Exp. Station)
• Dr. Wayne Zipperer
• Dr. David Nowak

3
Purpose

• Develop and test field survey methods for
  collecting and validating data using traditional
  data collection methods and wireless Geographic
  Information System (GIS) and Global Positioning
  System (GPS) technologies

4
Objectives

• Develop a Study Plan
• Obtain Approval
• Implement Study Plan
• Present or Publish Findings

5
Study Plan

• Select the study site
• Determine data collection methods
• Determine method evaluation criteria
• Identify data requirements
• Evaluate and obtain survey equipment, hardware,
  and software
• Hire contractor or train staff
• Prepare for field survey
• Conduct field survey
• Perform post-processing and quality assurance
• Analyze data
• Present Findings

6
Study Site Bethesda Neighborhood
7
Data Collection Methods

• Traditional
• Hard-copy field inventory Sheets and Maps
• ArcView GIS software
• Hand-held GIS
• Compaq IPAQ 3670 with Windows CE Version 3.0
• ESRIs ArcPAD 5.0.1 and ArcView GIS software
• Data downloaded locally and via the Web through
  Internet Map Services
• GPS
• Trimble GPS Pathfinder Pro XR Receiver with TSC1
  Data Collector
• Pathfinder Office Software included
• Pre-planning
• Data dictionary

8
Traditional Method
9
Hand-held GISCompaq IPAQ with ArcPAD and
Merlin Wireless Modem
10
Trimble Pathfinder Pro XR GPS
Antenna
TSC 1 Data Collector
Pathfinder Office
11
Evaluation Criteria

• Spatial Accuracy
• Proximity Analysis conducted using ArcView GIS
• Time
• Field Preparation
• Field Survey
• Post-processing
• Analysis
• Costs
• Staff
• Training
• Materials/Expenses
• Desktop computer, Compaq IPAQ, ArcPAD ArcView
  software, printer, travel,etc..
• GIS Data

12
Data Requirements

• Montgomery County Department of Environmental
  Protection
• Focus on Street Trees initially then progress to
  residential or privately owned trees
• Tree ID , Species, DBH, Height, Height to Crown,
  Crown Diameter, Health, Comments
• Spatial data to be in ArcView shape file
  compatible format
• Projection Maryland State Plane
• Datum NAD 83
• Map units Feet
• American Forests CITYgreen Model
• Tree ID , Ownership (Public or Private), Species
  Code, DBH, Height to top of Tree, Reduced in
  Height, Health, Conflicts (overhead wires,
  structure, sidewalk, other trees), Ground Cover
  under canopy (shrubs, grass, pavement, exposed
  soil, mulch)
• Height Class and Diameter Class were calculated
• United States Forest Service Urban Forest Effects
  (UFORE) Model
• Tree ID , Street Tree (Y/N), Species Code, DBH,
  Height to top of Tree, Height to Base of Crown,
  Health, Crown Width, Foliage Density, Percent
  Dieback, of Sides receiveing Sunlight (0
  below 5 above canopy)

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Equipment, Hardware, and Software

• All Methods
• Tree measurement tools
• Measuring chain or stick, clinometer, DBH tape,
  or equivalent
• Clipboards and pencils
• Camera
• Olympus Digital Camera (3 mega-pixel)
• Desktop PC and printer used to create and print
  data sheets and maps and to run analysis or
  planning software
• Dell Precision 330 1.5ghz with 512mb RAM with 20
  gb hard-drive
• HP 2000 C color printer
• ArcView GIS Software

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Equipment, Hardware, and Software

• Hand-held Computer
• Compaq IPAQ 206 mhz pentium
• Windows CE operating system
• 16 mb ROM (Flash) . Could expand up to at least
  128 mb
• 64 mb RAM
• Color display (240 x 320)
• ArcPAD 5.0.1 and ArcView 3.2 software
• Desktop PC (Dell Precision 330 1500 mhz with 500
  Kb RAM and 20 GBs hard drive) with Windows
  2000
• Merlin Cellular Digital Packet Data (CDPD)
  Wireless Modem - 19.2 kbps (Optional)
• Voice recognition software (Optional)
• Naturally Speaking by Dragon Systems
• Voice Insight (ArcPAD 6)

15
Equipment, Hardware, and Software

• Trimble Pro XR/Beacon with TSC1 GPS Unit
• Backpack unit with a hand-held TSC1 data
  collector
• Capable of Real-Time Differential GPS Corrections
  (DGPS) through the US Coast Guard Beacon system
  or a private satellite subscription service
• Spatial accuracy to 50 cm
• Pathfinder Office Desktop Software
• Desktop PC - (Dell Precision 330 1500 mhz with
  500 Kb RAM and 20 GBs hard drive) with
  Windows 2000

16
Hire or Train Staff

• Hired a Qualified Professional Forester to assist
  with the tree survey
• Obtained Trimble GPS training from Sam Walker
  Scinnovations Inc.

17
Field Survey Preparation Traditional

• Developed an inventory sheet to satisfy data
  requirements
• Generated hard-copy maps using ArcView GIS
  software
• Plotted street trees on maps for validation
• Maps were laminated for protection
• Covered clipboard used to protect data sheets
• Coordinated field visits with Contractor

18
Field Survey Preparation Hand-held GIS

• Install and configure ArcPAD 5.0.1 and ArcView
  GIS software on Dell Precision 330 Desktop PC and
  Compaq IPAQ 3760
• Created a new tree file and digital inventory
  sheet using ArcView 3.2 and ArcViews Dialog
  Designer Extension
• Digital inventory sheets reduce error by
  enforcing field validation and incorporating
  pre-determined list boxes or choices specified in
  the data requirements
• Downloaded data file, digital inventory sheet,
  GIS shape files (roads and street trees), and a
  color digital ortho-photo (one-foot pixel
  resolution) of the study area to Compaq IPAQ
  mobile mapping device with ArcPAD 5.0.1
• Set up the ArcPAD project file on the IPAQ using
  the downloaded data and digital inventory sheet
• Incorporate voice recognition (Optional)
• Voice Insight for ArcPAD 6 soon available
• Configured the wireless Merlin modem and the
  wireless Internet service for the PDA from
  Verizon Wireless, Inc

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ArcPAD Digital Inventory Sheet
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Field Survey Preparation GPS

• Installed the Trimble Pathfinder software onto a
  Desktop PC and prepared the GPS unit for field
  work (charge batteries and check cables)
• Created a Data Dictionary in accordance with the
  data requirements using the Pathfinder Office
  software and transferred it to theTSC1 data
  collection unit
• The data dictionary reduces error by enforcing
  field validation and incorporating pre-determined
  list boxes or choices specified in the data
  requirements
• Downloaded the latest Almanac Information from
  the local GPS base station (within 300 miles for
  sub-meter) using the Pathfinder software
• Created a Mission Plan to determine the number of
  available GPS satellites as well as the
  anticipated Position Dilution of Precision (PDOP)
  using the Pathfinder software
• PDOP is an index used by the GPS device that
  measures satellite geometry and predicts
  positional accuracy. If the PDOP is low, then the
  GPS satellite constellation is spread out, which
  yields a more accurate position.
• The PDOP mask was set to 6, the number of
  positions mask was set to 1 position per second
  for 30 seconds, and the elevation mask was set to
  15 degrees
• A new point file was created using the GPS TSC1
  Data Collector. The data dictionary was
  incorporated, so that each time a tree was
  located the surveyor could enter the attribute
  data required

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Field Survey

• All Methods
• Street trees were inventoried initially
• Consent letters, created to notify local
  residents for permission to inventory trees on
  private property, had not been delivered the
  survey was started
• The tree location (point) and attribute
  information were recorded in the field
• A team of at least two collected data
• One person recorded the tree location, attribute
  information, and measured tree height while the
  other person conducted the other tree
  measurements
• Photos were taken with digital cameras for
  presentation and web publication
• Traditional Method
• Tree location and identification number were
  recorded on a hard-copy map
• Tree attribute information, including tree
  identification number, were recorded on a data
  sheet
• A crew of two were able to complete about 30 to
  40 trees per hour during a typical humid
  sub-tropical summer day (90 degrees F with 95
  humidity)

22
Field Survey Traditional Method
23
Field Survey Hand-held GIS

• Tree location and attribute information,
  including tree identification number, were
  recorded using the Compaq IPAQ/ArcPAD 5.0.1
• The tree location was eye-balled using
  landmarks identified in the field that could be
  distinguished on the downloaded digital
  ortho-photo
• The IPAQ color display screen (240 x 320) was
  clearly visible in the field
• As a tree was added to the database, the digital
  inventory sheet popped up and enabled the
  operator to enter the attribute information
  quickly and easily
• A crew of two were able to complete about 20
  trees per hour during a typical humid
  sub-tropical summer day (90 degrees F with 95
  humidity)
• One person recorded the tree location, attribute
  information, while the other person conducted the
  other tree measurements
• The IPAQs LiPolymer battery-power lasted about 2
  hours and 15 minutes. You can recharge the
  battery using an automobile A/C adapter. However,
  be careful not to plug it in when you start-up
  the car
• The wireless data connection (19.2 kbps) from the
  County GIS Internet Map Server (IMS) did not work
  in the Study Area
• When a connection was established (outside of the
  study area), it took about 1 minute to refresh
  the IMS photo (19.2kpbs) while it took lt 5
  seconds to bring up the photo stored on the
  IPAQs Flash ROM
• The downloaded photos were used in the field to
  map the trees

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Field Survey Hand-held GIS
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Look for Wireless Redwoods near you!
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(No Transcript)
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Field Survey GPS

• Tree location and attribute information,
  including tree identification number, were
  recorded using the Trimble Pathfinder Pro XR GPS
  receiver and TSC1 Data Collection unit
• The tree position was recorded in the GPS data
  receiver/logger for at least 30 seconds. This
  would yield sub-meter positional accuracy
  required
• The Trimble LCD screen (240 x 200) was clearly
  visible in the field
• As a tree position was added to the GPS database,
  the data dictionary popped up and enabled the
  operator to enter the attribute information
  quickly and easily
• A crew of two were able to complete about 20
  trees per hour during a typical humid
  sub-tropical summer day (90 degrees F with 95
  humidity)
• One person recorded the tree location, attribute
  information, while the other person conducted the
  other tree measurements
• Tree positions were recorded when PDOPs lt 6.
  When a structure or heavy tree canopy/biomass
  blocked the satellite feed, then the surveyor
  conducted an off-set. This occurred on lt 10 trees
  measured
• The GPS batteries lasted all day (at least 8
  hours), provided that they are charged the night
  before conducting the field survey

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Field Survey GPS Method
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Post-processing and Quality Assurance

• Traditional Method
• Attribute information from the field data sheets
  were entered into a Microsoft Access database
• Tree points were interpolated from the maps and
  digitized into a GIS shape file using ArcView
• Property lines, building foot-prints, and roads
  were used to interpolate the position of the
  trees
• Reviewed attribute data for data entry mistakes
• Spelling mistakes
• Incorrect Species Codes
• Examine the Comments field
• Placed tree points over the digital ortho-photo
  using ArcView and visually reviewed the spatial
  accuracy to ensure that the data points were in
  the correct map projection

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Post-processing and Quality Assurance

• Hand-Held GIS Method
• Download GIS shape file or data file to Desktop
  PC
• Reviewed attribute table for data entry mistakes
• Overlayed GIS data on digital ortho-photo and
  visually reviewed spatial accuracy
• Wrote ArcView script to Grow Trees based on
  crown diameter for CITYgreen model
• Trimble Pro XR GPS Method
• Transferred data to Desktop PC
• Downloaded base-station differential correction
  files
• Performed differential correction using
  Pathfinder Office software
• Converted to GIS shape files with the correct map
  projection parameters
• Reviewed attribute table data entry mistakes
• Overlayed GIS data on digital ortho-photo and
  visually review spatial accuracy
• Check the off-sets

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Analysis

• Sample Size 31 trees
• Used GPS points as the Control
• Conducted Proximity Analysis using ArcView 3.2 to
  estimate spatial accuracy of the Hand-held GIS
  and Traditional methods
• Wrote a script to compute distances from GPS
  points to Hand-held GIS and Traditional method
  points
• Calculated average, minimum, and maximum distance
  to each corresponding tree based on unique
  identifier field (Tree_id)
• Recorded time and costs for each method

32
Proximity Analysis
Blue Traditional Green Hand-held GIS
Red GPS
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Findings Traditional

• Spatial Accuracy (Hand drawn on map and
  digitized)
• Average 13 feet off
• Minimum 2.5 feet off
• Maximum 50 feet off
• Time
• Field Preparation 2 hours
• Field Survey 30 to 40 trees per hour for 2
  hours
• Post-processing 3 hours
• Data Conversion (entry) is necessary
• Analysis 1 hour
• Total 8 hours
• Costs (Prices are subject to change)
• Staff 240 x 2
• Training 0 per hour
• Materials/Expenses 4,850
• Desktop computer (3,500), ArcView (900),
  printer (400), travelfood (30), other (20)
• GIS Data 425
• Total Cost 5,755

34
Findings Hand-held GIS

• Spatial Accuracy
• Average 7 feet off
• Minimum 2 feet off
• Maximum 22 feet off
• Time
• Field Preparation 3 hours (On-the-Job-Training)
• Field Survey 20 trees per hour for 2 hours
• Post-processing 1 hour
• Analysis 1 hour
• Total 7 hours
• Costs (Prices are subject to change)
• Staff 210 x 2
• Training 0 per hour
• Materials/Expenses 5,845
• Desktop computer (3,500), IPAQ (500), ArcPAD
  (495) ArcView (900) software, printer (400),
  travel food (30), other (20)
• Wireless service (300) modem (150) or IMS
  Server (22,000) not included in the price
• GIS Data 425
• Total Cost 6,690

35
Findings GPS

• Spatial Accuracy (Used as the Control)
• lt 3 feet off or sub-meter accuracy after
  Differential Correction
• Time
• Field Preparation 1 hour
• Field Survey 20 trees per hour for 2 hours
• Post-processing 1 hour
• Analysis 1 hour
• Total 5 hours
• Costs (Prices are subject to change)
• Staff 150 x 2
• Training 495
• Materials/Expenses 15,850
• GPS Unit (11,000), Desktop computer (3,500),
  ArcView 3.2 (900), printer (400), travel
  food(30), other (20)
• GIS Data 425
• Total Cost 17,070

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Summary

• Traditional Method
• Low cost solution
• Spatial accuracy is generally unacceptable for
  County base-mapping
• Need large scale field maps with planimetric data
• Accuracy could be improved if tree locations were
  measured from landmarks in the field, however,
  this would slow field survey speed
• Able to survey 30 to 40 trees in the field per
  hour
• Post-processing takes time
• Data entry is required
• Chances of data error are higher
• Requires little computer training
• Most popular method

37
Summary

• Hand-held GIS (Most Scalable Solution for Urban
  Areas)
• Affordable solution for County Government
• Easy to use in the Field
• Portable (fits in your shirt pocket), screen
  resolution is acceptable
• Voice recognition will be available in ArcPAD 6
  through Voice Insight, Inc.
• Spatial accuracy is border-line acceptable for
  County base-mapping
• Landmarks in the field can be interpreted on the
  ortho-photos to enable users to place the tree
  point locations within 7 feet of its exact
  location without measuring. Accuracy could be
  improved if tree locations were measured from
  landmarks in the field, however, this would slow
  field survey speed
• Able to survey a good average rate of trees per
  hour (20)
• Very little post-processing required
• Attribute data stored on IPAQ in the field
• Reduces post-processing error
• Enables access GIS data sets and ortho-photos
• Data downloaded onto IPAQ Flash ROM is currently
  the best solution
• ArcIMS Internet Map Services provide data to
  wireless IPAQ units and ArcPAD enables users to
  use the map services. Existing cellular modem
  technology is very slow (19.2 kbps) and you may
  have difficulties establishing a connection with
  the service provider, especially if you are in a
  low area. Modem technology is improving though
  (i.e. Ricochet, Merlin GT100).
• Provides connectivity to a GPS device for
  navigation and mapping
• Good for rural areas
• Requires hand-held computer and GIS training

38
Summary

• GPS
• Somewhat expensive solution
• If you need engineering or survey quality
  accuracy, this solution works great!
• Spatial accuracy is excellent for County
  base-mapping
• Minimal field preparation time
• Charge batteries, check cables, create data
  dictionary, download Almanacs from base station,
  quick plan, download dictionary to TSC1 data
  collector and go!
• Able to survey a good average rate of trees per
  hour (20)
• Occasionally had to wait for the PDOP to drop
  below 6
• If youre in a deep swale or next to large
  structures, you may have difficulty obtaining a
  good PDOP value (lt6). Heavy tree canopy/biomass
  may also some connection difficulties
• Backpack could be cumbersome for a smaller framed
  person
• Very little post-processing required
• Attribute data stored on data collector in the
  field
• Reduces data post-processing errors
• Recommend GPS and GIS Training

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Useful Web Sites

• Montgomery County GIS http//gis.co.mo.md.us
• Montgomery County DEP http//www.co.mo.md.us/servi
  ces/dep/
• USDA Forest Service, Urban and Community Forest
  Ecosystem Research http//www.fs.fed.us/ne/syracu
  se/
• American Forests http//www.americanforests.org
• Trimble GPS http//www.trimble.com/mappinggis.htm
  l
• ESRIs ArcPAD http//www.esri.com/software/arcpad
  
• Compaq IPAQnet Mobility Solutions
  http//www.compaq.com/products/wireless/wwan/index
  .shtml
• Novatel Wireless http//www.novatelwireless.com/p
  cproducts/merlin.html
• Verizon Wireless Service http//www.app.airtouch.
  com/mobile_ip/internet_access/pocketpc.html
• Dragon Systems http//www.dragonsys.com (Voice
  Recognition)