What Can UAV(S) Do That Cheap Satellites (And Field Scientists) Can’t?

1. What Can UAV(S) Do That Cheap
Satellites (And Field Scientists)
Can’t?
Lyndon Estes
Princeton University

2. What is a UAS?
Large
Medium
Small
Micro
Anderson & Gaston, 2013
Fixed Wing
Rotary
Buoyant

3. 3

4. Extent
Error/Bias
Our Current Observing Methods

5. The Mountain Bongo Antelope
Tragelaphus eurycerus isaaci
Why I Got Interested in UAVs

6. Prob.
occurrenc
e
Estes
et
al,
2012,
Animal
Conservati

8. Bongo
presence
observations
w/o
field
data
Bongo
presence
observations
w/field
data
Non-­‐presence
observations

9. Initial analysis of Bongo Habitat Selection
Understorey structure – 400 m2
-> Field data
Patch structure – 20 ha
-> ASTER + Spectral Mixture
Analysis
~450 m
Estes et al, 2008, Remote Sensing of Environment

10. 10
20
30
40
50
60
70
80
10 20 30 40 50 60 70 80 90
Observed
SCI
score
Predicted
SCI
score
X
o
Non-­‐presence
obs
(training)
+
Bongo
obs
(test)
Mean
of
non-­‐presence
obs
Mean
of
bongo
obs
Model
–
5
ASTER-­‐derived
predictors
3
Spectral
Mixture
Analysis
2
texture
variables
R2
=
0.46
RMSE:
Training
=
17%
Test
=
19%
Estes
et
al,
2010
(Remote
Sensing
Environment)
Mapping
Structural
Complexity
Indices

11. Structural
Complexity
Index
Canopy
“Middlestorey”
Herbaceous
understorey
?
✓

12. ~450
m
Hand
launch
a
small
UAV…
…And
collect
high
quality
data
in
transects,
rather
than
slogging
it
• Understorey
+
canopy
• 3
dimensions
• Micro
–
landscape
scale
• Every
few
weeks

13. Estes, Chaney, Herrera-Estrada, Sheffield, Caylor, Wood, 2014, ERL
Bringing the Satellite Closer to The Field
Beat down error in remotely sensed yield estimates
Crop-specific NDVI signature
Estes et al, 2013, Glob Ecol Biogeog, Glob Change Biol

14. Calibrate/Validate Crop Models
Generalized Additive Model of Maize Yield

15. Process-­‐based
Model
accuracy
at
400
km2
DSSAT

16. Accuracy
at
Provincial
Scale

17. UAVs
over
agricultural
landscapes
• Crop
type
• Sowing
date
• Flowering
• NDVI/LAI
–
weekly
to
bi-­‐weekly
• Microtopography
• Surface
soil
moisture?

18. 18
Crop model -> yield + LAI

19. MODIS
Landsat
Crop
Fields
in
Eastern
Province,
Zambia
Daily
Every
16
days

21. 21

22. Extent
Error/Bias
Environment Observing Methods

23. For effective use of UAS
Need:
1. Geometrically
2. Optically
3. Automated
Rectification
of
collected
data
in
space
&
time
domains
23

24. Course Goals
By end of week:
1. Understand what can (and probably cannot) be done
with UAS
2. Learn how to plan and fly mission
3. Successfully post-process imagery, and understand
key factors to correct
4. Basic analysis of results