The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
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data is small enough, each segment can be considered as the 
approximate cylindrical or truncated cones. However, Its 
disadvantage is that there are some difficulties in the data 
collection of trees’ changing point and inevitably lose some 
volume data. 
Fig. 1 Calculate exterior area and volume of trunk by trunk 
simulation based on column and frustum of a cone 
2.1.2 Collecting the point clouds of the tree stem to produce the 
surface of the stem to calculate volumes 
This method is suitable for the trees with straight trunk and less 
turning or with small angle, which is easily for choosing the 
projection plane (See below in Fig. 6 and Fig. 7) 
Fig. 2 Trunk simulation by data of point clouds 
2.1.3 Traditional method of subsection integration to estimate 
the tree volume 
This method, which is the traditional method in forestry, is to 
divide the trunk into several segments according to the forestry 
regulation. Through the manipulation of rotation, translation, 
zooming and angle changing, the segment diameters and 
height can be measured. Then, the tree volume can be 
calculated through the equation (See below in Fig.8) 
Fig.4 Measure the volume by mid-area 
2.2 Stand crown measurement 
In the measurement of stand crown volume, there are much 
differences with the tree stem measurement. As the crown is 
not a stationary solid form like the stem, there are many 
vacuity in the crown. The laser beam may penetrate the crown 
and form the reflection in it. So, the point cloud data we get 
can not totally reflect the spatial features of the outer crown. 
There are two methods to get the 3D models of the crown. 
The first is to do some pre-process to the data acquired. We 
use Cyclone software to rotate and zoom the point cloud data, 
and then, manual interpretation is used to interprete the points 
that are not on the surface of crown and remove them. Next, 
we use the surplus data to set up a spatial Irregular Triangular 
Network (TIN) net, and calculate the surface area and volume 
of the TIN model according to the space geometry, 
approximate to the surface area and volume of the crown. 
The other method is to take the whole crown of the single tree 
as the components of the single small truncated cones. Then, 
we measure part of the point data of the crown to calculate the 
surface area and volume of each small truncated cone. Next, 
all the results are added up and the surface area and volume of 
whole crown in the space are calculated. (See below in Fig5) 
Stand crown calculation by height differences hj of each cross 
section: 
Fig.3 Measure the volume by Mesh of trunk