International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
  
orthophoto. The result of measurement is given in untitled 
message box in the left image. 
  
Jes. Sie ied : 
TOLL ee 
Pr Aad 
  
  
Figure. 9. Manual mode measurements 
The precision of manual measurements is higher then obtained 
by automated procedure, but manual mode is sufficiently slower 
and can include operator’s errors. 
3.2.8 Stereo pair measurement technique: For circles 
detection in this method the above described algorithm is used. 
After circles detection their stereo matching is performed using 
epipolar geometry and determined image size of detected circle. 
For candidates with similar parameters the choice is performed 
on condition that spatial circle has to lie near middle plane of all 
reliable circles. The comparison of results for two different area 
estimation techniques show that both methods give adequate 
estimation for cuts area but method based on 
orthotransformation technique is more robust and fast. 
4. LOG VOLUME MEASUREMENTS 
Another important task is volume measurement of a log moving 
on a conveyor belt. The real conveyor of log processing is 
shown in Fig. 10. The workspace does not allow sceing the 
whole surface of the log. So for volume estimation the 
following technique is proposed. A log is lighted by stripe line 
during its movement along the conveyor and images of the log 
in this light are acquired with camera frame rate. It allows real- 
time calculating a set of log’s profiles with frame rate frequency 
and to generate a 3D model of the log which is used for volume 
estimation. 
  
  
  
Figure 10. Log processing conveyor 
The laboratory model of conveyor is used for the technique 
development. The result of log surface reconstruction using one 
camera is presented in Fig.11. Fig. 1a demonstrates that one 
camera allows to reconstruct approximately 30-40% of the log 
surface. This information can be used for circle approximation 
of the log sections and its volume estimation. Fig. 11b shows 
several reconstructed sections of the log. 
  
Figure 11. Log 3D model 
The results of log volume estimation by described technique for 
a set of 50 logs were compared with independent measurements. 
The precision of non-contact measurements was at the level of 
9%. 
5. CONCLUSIONS 
Automated non-contact photogrammetric techniques are 
proposed for measurements in woodworking industry. Two 
methods for logs package area measurements are proposed 
based on image processing for circles detection. The precision 
of both methods are similar, orthotransformation technique 
being more robust and productive. 
In automated mode the performance of 3D measurements is 
about 8 seconds per package, the accuracy of measurements is 
at the designed level of | mm for the described laboratory 
system configuration. These characteristics are quite enough for 
today needs of wood industry. All measurements can be 
performed by “one-button-click”. 
The system for cut area measurements can be applied in off-line 
mode acquiring images and saving them for further processing 
in automated or semi- automated mode. On the current stage of 
system development semi-automated mode is more reliable and 
precise due to operator control of circles extraction. The 
accuracy of measurements in off-line mode is at the level of 0.1 
    
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