International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004 
  
  
  
  
  
  
  
  
  
  
  
The results of the derivation processes are compared with the (i.e. numbers, locations and lengths of skeleton lines, and 
valley lines of the terrain produced by the operator from the coherent relationships between the contours and the skeleton TRI/ 
stereo models of the area, because the operator has drawn the lines) are used. 
valley lines only as it is usual. However, the methods are able 
to derive both valley and ridge lines. In comparison with the valley lines drawn by the operator, the 
valley lines derived from the DEM are quite different. All 
+ valley lines to be expected are not derived. However, an 
sus M unexpected valley line appears. Lengths of some valley lines 
tyres are shorter. The relationships between the contours and the 
T valley lines are not good, i.e. the valley lines do not cross the 
e [ar re contours at right angle. On the other hand, the valley lines KEY \ 
/ derived from the contours are quite similar to that are drawn by 
/ Ty the operator from the same aspects. Number of valley lines is 
ee A ne almost same except three small branches. They appear in the 
Ted Fs X same regions. Their lengths are almost equal. They are also ABSTI 
I. PN 6 y N | satisfactory with respect to the relationships between them and We prc 
= a V X the contours. triangle 
= / Y { is intro 
ee Y x the groi 
des % 5. CONCLUSIONS TPM s 
b p X \ I i En related 
r F 1 [n this study, two methods developed for deriving skeleton lines sorting, 
of terrain from contours and DEMs are compared in accordance The vis 
Figure 14. Valley lines drawn by the operator in the stereo with the results obtained from the same data set. The results of aerial it 
model the first method developed by Aumann et al. (1991) are more can be 
satisfactory than the second method developed by Chang et al. orthoim 
T S (1998) from several aspects such as numbers, lengths and 
zeit A locations of the skeleton lines and the relationships between the 
€ y \ contours and the skeleton lines. However, it should be noted 
et that this evaluation is not true for every case; because the 
——— A second method has a parameter (i.e. length of profile) and thus Many c 
e different results can be obtained if different values are assigned facilitat 
N to it. Buildin 
ilt SN simplif 
Ness. A E parts © 
A NU \ | REFERENCES occlusi 
x 7” à types | 
Teg / \ Y Aumann, G., Ebner, H., and Tang, L., 1991. Automatic orthoin 
M Jf \ Derivation of Skeleton Lines from Digitized Contours. /SPRS Our me 
opr” X Journal of Photogrammetry and Remote Sensing, 46, pp. 259- buildin; 
r e D ( y IN 268. betwee 
> f x m x nes ; = limitati 
Aumann, G., 1994. Aufbau Qualitativ Hochwertiger Digitaler triangle 
: : : ; Geleandemodelle aus Höhenlinien. Dissertation, Technischen planar 
Figure 15. Valley lines derived from the contours Universiteat München. S Mi 
: TPM si 
Chang, Y. C., Song, G. S., and Hsu, S. K., 1998. Automatic model: 
Extraction of Ridge and Valley Axes Using the Profile related 
À Recognition and Polygon - Breaking Algorithm. Computers & project 
\ Geosciences, 24(1), pp. 83-93. introdu 
be Chang, Y. C. and Frigeri, A., 2002. Implementing the inea 
| N Automatic Extraction of Ridge and Valley Axes Using the PPA Where 
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Tm L EN Conference 2002, 11-13 September 2002, Trento, Italy. NOLO 
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SC MA THT { Gokgoz, T., 1999. A New Approach for Simplification of explain 
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D \ Giilgen, F., 2003. Automatic Derivation of Skeleton Lines of The pr 
Mice \ Terrain from Digital Elevation Models. M.Sc. Thesis, Yildiz 
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T f \ 
E Finsterwalder, R., 1986. Zur Bestimmung von Tal- und 2.1 De 
Figure 16. Valley lines derived from the DEM an Zeitschrift fiir Vermessungwesen, 111, pp. 184 Trang 
For comparison, some measurements related to cartographic finite n 
and geomorphologic properties of contours and skeleton lines 
622