comparing trail mapping approaches
DESCRIPTION
This is a presentation completed in the GIST program at USC. Three students compared the precision of three different approaches to trail mapping. Methods used included Google Earth, Trimble Juno 3B, and the iOS MotionX app. The presentation outlines the methods and the pros and cons of each device.TRANSCRIPT
1 1
Amy Anderson
Katie Lima
Melissa Pierce
August 4, 2013
Comparing Trail Mapping
Approaches
2 2
Content
Proposal review
Adjustments to project
Data dictionary
Methodology flow charts
Precision comparison maps
Advantages and disadvantages of technology
Comparison table
Assessment of project
Lessons learned
Sources
3
What are the advantages and disadvantages of using
different technology for deriving trail maps?
Recapitulate Original Proposal
Figure 1: Study area and trail
USC Wrigley Institute
Pacific Ocean
Catalina Island
Deer Valley Trail
4
- Order of project
- Digitization interface
- Adjusted data focus
Adjustments to Original Proposal
Figure 2: iOS data collection at trail head
5
Google Earth Trimble Juno 3B iOS MotionX app
create/test data dictionary
send data dictionary to device
set parameters set parameters set parameters
digitize path collect data (x,y, not z) collect data (x,y, not z)
send field data file to pathfinder
differential correct
export as kml export .cor to ArcGis shape file share gpx file via email
convert gpx to features
convert KML to layer import to ArcMap convert points to line
2 Maps: 3 lines + 1 polygon 2 Maps: 3 lines + 1 polygon 2 Maps: 3 lines + 1 polygon
Lin
es
Feat
ure
to
Po
lygo
n
1. Assess study area
2. Collect data 3 times for each method described below
3. Compare and analyze data created:
Pre
-Co
lle
ctio
nD
evi
ce W
ork
Arc
Map
SHP SHP
⌂ ⌂ ⌂
SHP SHP SHP SHPlyr lyr lyr
KML KML KML GPX GPX GPX
Each gray box represents 1 map
M
E
T
H
O
D
O
L
O
G
Y
Figure 3: Methodology chart
6
Google Earth Trimble Juno 3B iOS MotionX app
create/test data dictionary
send data dictionary to device
set parameters set parameters set parameters
digitize path collect data (x,y, not z) collect data (x,y, not z)
send field data file to pathfinder
differential correct
export as kml export .cor to ArcGis shape file share gpx file via email
convert gpx to features
convert KML to layer import to ArcMap convert points to line
2 Maps: 3 lines + 1 polygon 2 Maps: 3 lines + 1 polygon 2 Maps: 3 lines + 1 polygon
Lin
es
Feat
ure
to
Po
lygo
n
1. Assess study area
2. Collect data 3 times for each method described below
3. Compare and analyze data created:
Pre
-Co
lle
ctio
nD
evi
ce W
ork
Arc
Map
SHP SHP
⌂ ⌂ ⌂
SHP SHP SHP SHPlyr lyr lyr
KML KML KML GPX GPX GPX
Each gray box represents 1 map
M
E
T
H
O
D
O
L
O
G
Y
Feature to polygon example
7
Results: Google Earth Digitization
Polygon area: 73,628.93 sq. ft. Figure 4: GE precision comparison
8
Advantages of GE Digitization
- Inexpensive
- Can be used by an inexperienced data collector
- Little preparation and processing
- Does not require ground truth
- Not time consuming
Disadvantages of GE Digitization
- Not as precise as other technology
- Digitization accuracy will depend date of imagery
- Minimal attribute editing ability
- Accuracy unknown
9
Google Earth Trimble Juno 3B iOS MotionX app
create/test data dictionary
send data dictionary to device
set parameters set parameters set parameters
digitize path collect data (x,y, not z) collect data (x,y, not z)
send field data file to pathfinder
differential correct
export as kml export .cor to ArcGis shape file share gpx file via email
convert gpx to features
convert KML to layer import to ArcMap convert points to line
2 Maps: 3 lines + 1 polygon 2 Maps: 3 lines + 1 polygon 2 Maps: 3 lines + 1 polygon
Lin
es
Feat
ure
to
Po
lygo
n
1. Assess study area
2. Collect data 3 times for each method described below
3. Compare and analyze data created:
Pre
-Co
lle
ctio
nD
evi
ce W
ork
Arc
Map
SHP SHP
⌂ ⌂ ⌂
SHP SHP SHP SHPlyr lyr lyr
KML KML KML GPX GPX GPX
Each gray box represents 1 map
M
E
T
H
O
D
O
L
O
G
Y
10
Data Dictionary
Trail (Line) Log Interval: 1 Second Offset: 0
Comment Length 100
Date of Collection MDY format Auto Generate on Creation
Time of Collection 24 hour format Auto Generate on Creation
Hazard (Point)
Type of Hazard Rock Cactus Tree Branch Tree Root Other
Photo
Action Needed? Yes No
Comment Length 100
Date of Collection MDY format Auto Generate on Creation
Time of Collection MDY format Auto Generate on Creation
Trail Sign (Point)
Sign Subject Length 100
Photo
Comment Length 100
Date of Collection MDY format Auto Generate on Creation
Time of Collection 24 hour format Auto Generate on Creation
If Yes…
Comment Length 100
Figure 5: Trimble Juno 3B
11
Parameters
WHAT IS A HAZARD? • Blocks 1/3 of the trail
• Sticks up jagged out of ground any items that could easily trip a person
• Any part of a cactus over any part of the trail
• Anything hanging six feet or lower over the top of the trail
• ‘Other’ is up to your discretion
Figures 6-10: Root, multiple hazards, rock, cactus, tree branch
12
Results: Trimble Juno 3B
Polygon area: 11,598.87 sq. ft.
Figure 11: Trimble Juno precision comparison
13
- Highly accurate and precise
- Reliable in field
- Files can be manipulated
- Attributes of features easily collected
- Relatively lengthy set-up processing time
- Requires several components
- Must upload imagery
- Not intuitive
- Expensive
Advantages of Trimble Juno 3B
Disadvantages of Trimble Juno 3B
14
Google Earth Trimble Juno 3B iOS MotionX app
create/test data dictionary
send data dictionary to device
set parameters set parameters set parameters
digitize path collect data (x,y, not z) collect data (x,y, not z)
send field data file to pathfinder
differential correct
export as kml export .cor to ArcGis shape file share gpx file via email
convert gpx to features
convert KML to layer import to ArcMap convert points to line
2 Maps: 3 lines + 1 polygon 2 Maps: 3 lines + 1 polygon 2 Maps: 3 lines + 1 polygon
Lin
es
Feat
ure
to
Po
lygo
n
1. Assess study area
2. Collect data 3 times for each method described below
3. Compare and analyze data created:
Pre
-Co
lle
ctio
nD
evi
ce W
ork
Arc
Map
SHP SHP
⌂ ⌂ ⌂
SHP SHP SHP SHPlyr lyr lyr
KML KML KML GPX GPX GPX
Each gray box represents 1 map
M
E
T
H
O
D
O
L
O
G
Y
15
Results: iOS
Polygon area: 66,520.12 sq. ft.
Figure 12: iOS precision comparison
16
- Limited attribute collection and manipulation
- Temperamental application
- Unreliable if cellphone coverage is spotty
- Not intuitive
- Wide range of accuracy
- Storage problem
Advantages of iOS
Disadvantages of iOS
- Relatively inexpensive
- Minimal processing time
- Yields clearer photos
17
Results Map: Three Technical Devices
Figure 13: polygon comparison of three technologies
GE 73,628.93 sq. ft. Trimble 11,598.87 sq. ft. iOS 66,520.12 sq. ft.
18
Google Earth Trimble Juno
3B
iOS MotionX
appSetup time L K
Time to digitize / collect data L K
Postprocessing time L K
Total Time (in hours) K L
Equipment / software needed L K
Accuracy of device n/a K
Field Reliability n/a L
File Manipulability L K
Precision (based on calculated area) L K
Access of imagery base maps L K
Photo capabilities n/a K
Ground level data attribute collection capabilities L K
Skill to use (Novice vs. Expert) L L
CO
ST
Associated costs L K
5 5 3
K 1 2 9
L 4 6 1
n/a 3 - -
TIM
ETE
CH
NO
LOG
YU
SAB
ILIT
Y
Table: Advantages/Disadvantages of Technology
Figure 14: comparison of three technologies
19
What worked well?
- Team cohesion
- Completed data collection with two days to spare
- Lack of tree coverage, favorable terrain and weather
- Used other teams as a resource
- Conducted pilot tests of the trail and devices
What did not work well?
- Initial interface for digitization
- Importing, differential correcting, projecting
- MotionX GPS service
20
- Each method has merit in certain situations
- Visualization tools can easily illustrate precision
without complicated formulas
- Planning and pilots are key
Take Always
21
Sources
Brown, Kevin. “GPS/GIS Workshop.” USC GPS/GIS Field Exercise. USC Wrigley Institute, Catalina Island,
CA. 30 July 2013. Workshop.
Esri. ArcGIS Resources. “Feature to Polygon” and “Projection.” help.arcgis.com/en/arcgisonline/help/. 7 July
2013. Web. 1 August 2013.
Esri, DeLorme, NAVTEQ © 2013. ArcMap Service Credit Layers. Web. 2 August 2013.
Fullpower Technologies, Inc. 2013. MotionX-GPS. http://www.motionx.com/.
Google Earth. Google Earth application. http://www.google.com/earth/index.html. Web. 31 July 2013.
Trimble. “Juno 3 Series Handhelds.” http://www.trimble.com/mappingGIS/juno3.aspx?dtID=applications&.
30 July 2010. Web. 2 August 2013.
22
Conclusion
QUESTIONS?
Melissa Pierce: [email protected] Amy Anderson: [email protected] Katie Lima: [email protected]