The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008
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Natural river profile statistics
Figure 1. Natural river’s profiles sampled on different sections
Artificai river profile statistics
Figure 2. Artificial river’s profile sampled on different sections
(the sampling points with a certain distance)
Sampling points
Figure 3. Highway’s profile sampled on different sections
(the sampling points with a certain distance)
sophisticated computation. This paper suggests using the logical
relationship of the locations for different height sections on the
profile, which can simplify the judgement process.
The following consideration about establishing the concrete
judgement functions takes the skeleton as the initial reference,
and ranges 2 times the distance from central line to the
extracted edge. Based on the sum up about the typical forms of
the profile distribution in the upper three figures, the logical
relationship between initial position, end position, highest
position and lowest position can be determined and be used for
making sure of different profiles. Then the discrimination
function can be summed up.
The profile factor logical function of natural river, highway and
artificial river can be summed up as formula (5), (6) and (7)
individually. If the real profile fits one of the conditions, then
the object can be determined as the related terrain catogery.
The profile morphological factors can be expressed as shape
functions forjudging. Highways are commonly with gutters and
the road surface is higher than the fields both sides, so its
profile can be united into “W” shape. Natural rivers are like
“U” without banks, while artificial water-bodys have riverbanks
and its profile can be simplified as “M” figure. Then
corresponding profile factor functions can be established for
calculation and judgment accordingly.
P = P
max lnit
P = P
max End
P < P < P
1 lnit min 1 End
(5)
(6)
2.3 Profile functions
For automatic identification, the distribution of rivers’ profiles
should be summarized into functions for logical judgement.
Natural rivers, artificial rivers and highways are individually
deduced as the shapes shown in figure 4. For highway and
artificial river, the upper shapes are more common, but the
lower ones still exist.
The concrete mathematical expression can assume sine function,
which distinguishes by the fitting range in different phase and
amplitude. The shape deployment also can be characterized by
different degree polynomial functions with various coefficients
as detection parameters. But these kinds of method above need
P = P
min lnit
P = P
mm 1 End
P <P <P
1 lnit 1 max 1 End
(7)
where P init = height of the point on the centreline
Pend = height of the point at the end of the profile
Pmax = height of the point with largest elevation
P min = height of the point with least elevation
The above discrimination functions need some pre-processes to
ensure the reliability of the practical judgement. Firstly, the data
for implementation should assume the average result of
