Applications of Spherical Photos for
Estimating Forest Attributes
Faculty of Forestry and Environment Management
Haozhou WANG
Supervisor: John A. Kershaw

Forest Introduction
Dominant Terrestrial Ecosystem• 75% biosphere gross primaryServiceproductivity• 80% of plant biomass

ForestSpecies

Complex ForestConditions• Watershed protection
Densities

How?

• Soil maintenance• Carbon Storage

SimpleAttributes

2

Tree Attributes Field Measurement
Trunk Info.

Clinometer

HeightMeasuring tapeSingle Tree
Attributes

Diameter
Diameter tape

Basal Area

Stand-level
Attributes

Angel gauge
Or “Plant Fraction” (PF)

Crown Info.

Gap Fraction

Fisheye camera

3Current problems
Trunk Info.
Time consuming

Clinometer

HeightMeasuring tape

Labor intensive

Diameter
Diameter tape

Revisit Validation

Basal Area
Angel gauge
Or “Plant Fraction” (PF)

Crown Info.

Unfriendly Price

Gap Fraction

Fisheye camera

4Integrate Tool
Trunk Info.

Clinometer

HeightMeasuring tape

Diameter
Diameter tape

Basal Area
Angel gauge
Or “Plant Fraction” (PF)

Crown Info.

Gap Fraction

Fisheye camera

5Spherical Camera
Trunk Info.
HeightDiameter

Basal Area

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

6

Spherical Camera: Height&Diameter
Trunk Info.
HeightDiameter

1. Take images at 2 different
elevations (E, E’)
2. Pair two spherical imagesby 3 control points
3. Mark the base and top of
the same tree in bothimages (α1, α2, β1, β2)

Basal Area

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

7

Spherical Camera: Height&Diameter
Trunk Info.
HeightDiameterθBasal Area

Lean EffectSlight lean(-5° to 5°)

IdeallyActual

Spherical camera

360° Information

Crown Info.
Plant FractionFriendly price ($400)
Light and Portable

8

Spherical Camera: Height
Trunk Info.
HeightDiameter𝑡𝑡𝑡𝑡𝑡𝑡 𝛽𝛽1 � 𝐸𝐸 − 𝑡𝑡𝑡𝑡𝑡𝑡 𝛼𝛼1 � 𝐸𝐸′
Height Dev. 𝛥𝛥𝛥 =𝑡𝑡𝑡𝑡𝑡𝑡 𝛼𝛼1 − 𝑡𝑡𝑡𝑡𝑡𝑡(𝛽𝛽1 )Distance tree2camera

𝐸𝐸 + ∆ℎ
𝑅𝑅 =𝑡𝑡𝑡𝑡𝑡𝑡(𝛼𝛼1)𝑅𝑅 � tan 𝛽𝛽2 + 𝑅𝑅 � tan(𝛽𝛽1)
𝐻𝐻 = 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 �𝑅𝑅 � tan 𝛼𝛼2 + 𝑅𝑅 � tan(𝛼𝛼1)Basal Area

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

9

Spherical Camera: Diameter
Trunk Info.
1.3 m

Height

1.3 m𝜃𝜃1. Find breast height
2. Mark the left andright edge of a tree
at 1.3m (breastheight)
3. Projected Angle ωDiameter

Basal Area

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

10Spherical Camera: Diameter
Trunk Info.
1.3 mHeight

𝜃𝜃

1.3 m

1. Breast height angle (𝜃𝜃)𝜃𝜃 = arctan(𝐸𝐸 + ∆ℎ − 1.3𝑚𝑚)
𝑅𝑅

2. DBH𝜔𝜔
𝑠𝑠𝑠𝑠𝑠𝑠� 𝑅𝑅
2
D/2 =𝜔𝜔
1 − sin( )2Diameter

Basal Area

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

11Spherical Camera: Basal Area
Trunk Info.
HeightDiameter

Basal Area

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

12

Spherical Camera: Basal Area
Trunk Info.
HeightDiameter

Basal Area

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

13

Spherical Camera: Basal Area?

1. Hidden Tree?
?

How different digital
sample locations helps

Trunk Info.
Heightdecrease its effect
Diameter

Basal Area

1. Three estimates better than one
2. The mean of three has smallest
deviation to on hidden tree effects
3. Target Count better than Edge
Marking

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

14

Spherical Camera: Basal Area?

1. Hidden Tree?
?

How different digital
sample locations helps

Trunk Info.
Heightdecrease its effect

2. Understory Density

Diameter

Trees HT < 1.3m notmeasured in field, but
may be marked in Photo

Basal Area

Spherical camera

360° Information

Understory tree does not have significant
impact on both marking methodologies

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

15

Spherical Camera: Basal Area?

1. Hidden Tree?
?

How different digital
sample locations helps

Trunk Info.
Heightdecrease its effect
Diameter

2. Understory Density
Trees HT < 1.3m notmeasured in field, but

Basal Area

may be marked in Photo

Spherical camera

360° Information

How stable of the novel
method among different

3. Inter-observer Error

users

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

16

Spherical Camera: Basal Area?

1. Hidden Tree?
?

How different digital
sample locations helps

Trunk Info.
Heightdecrease its effect
Diameter

2. Understory Density
Trees HT < 1.3m notmeasured in field, but

Basal Area

may be marked in Photo

Spherical camera

360° Information

How stable of the novel
method among different

3. Inter-observer Error

users

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable

17

Spherical Camera: Plant Fraction
Trunk Info.
HeightDiameter

Calibrate→Classify

Basal Area

Spherical camera

360° Information

Crown Info.
Plant Fraction

Friendly price ($400)
Light and Portable18

Thanks for listening
Questions？
Haozhou WANG
2019.06.24