ral wood samples at 
ed after felling. 
point spacing of 2mm 
»cedure) as well as a 
ts like traffic signs, 
eS. 
S 
f the voxel structure 
) this voxel domain. 
d in the subsequent 
suitable voxel size 
f the terrestrial laser 
est branches to be 
ver voxel should be 
of lcm like in this 
S of 3-Amm about 20 
can be subsequently 
noise or so-called 
in of terrestrial laser 
pecific approach was 
zontal layers of one 
are carried out: (i) 
1ation of voxels with 
st case those voxels 
ted to the tree, i.e. 
a). Based on a N26- 
'ourhood in 2D) ora 
is eliminated if all 
es that there is a gap 
cular points. 
applied to eliminate 
points, i.e. voxels 
hreshold. For rough 
ined by experience, 
iis threshold varies 
Ist be determined by 
Voxel) 
or determination of 
surfaces, i.e. voxels 
h contain no laser 
count for volume 
ation, closing) may 
r, 2004a), but the 
nsion of the hollow 
branches leading to 
reversed (e.g. by 
:hosen based on the 
d vision from four 
oes not need prior 
anches and stems. 
atical morphology) 
  
  
  
1 
1 
1 
1 
1 
1 
1 
1 
-—]—]—]—1-—]—]—1— 
e) 
  
ll af al nal tal nl 
  
1 
1 
1 
1 
1 
1 
1 
1 
—b | ree | ee | ie | eds | ie | eee 
reais | weeds | vite | eee | vis | weeds | ede | ite 
—]—1—]—1—1—1—1—- 
ildHiHiittuiiltiti 
f 
  
     
   
   
    
   
  
  
  
  
  
  
  
  
  
   
   
   
  
   
   
   
  
  
  
   
    
   
    
  
    
      
  
— 
—]—1]—]—1—1]—1—1—1—- 
  
Figure 1. Principle of filling process, a) Original surface voxels of a horizontal layer, b) — e) Marking of voxels of obstructed vision 
in four orthogonal directions, f) Intersection result of the four areas of obstructed vision, only voxels containing value v-4 are filled 
voxels for volume estimation