International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
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Computation of circuity is firstly definition of desired road
graph network in the form of fully connected one, d(i,j), and
then compare it with actual road graph network, e(i,j), in a
certain analysis zone. As the result in the case of figure 5, v,
and v, is nodes showing large level of circuity. Level of
accessibility is also related to the circuity computation process.
[nter- connected nodes in the same road graph are assigned to
unit value, and this result can be represented to square matrix
form, C'. This result can be directly utilized to obtain
accessibility level in the form of matrix. It represents easiness
of access among nodes in a given zone.
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Figure 6. Input data for computation of Circuity and
Accessibility: road graph layer and base
imagery
Figure 6 shows input data for circuity and accessibility matrix
computation. While, figure 7 is user interface of application
program and processing steps: <Step 1> ~ <Step 4>. In this
environment, first three steps are same to connectivity measure
on road network. Through <Step 4-1> and <Step 4-2> are for
calculation of circuity value at a node, each point, in the
analysis zone and calculation of circuity, connectivity, and
accessibility of the whole nodes in the analysis zone and their
representation in the matrix form, respectively.
The result of <Step 4-2 > is represented at figure 8, in the
normalized matrix form with maximum value of 1. Figure 9
shows network connectivity and accessibility matrix with figure
7.
3. CONCLUSION
It is known that high-resolution imagery 1s more
advantageous than coarse and medium resolution imagery. In
this study, GIS-based extraction application program for road
characteristics is implemented and tested in the viewpoint of
practical uses of thosé imageries. .
Select admin layer | Admin, nam, au.shp
«Step 2» Select Zone
C Using admin area | $s
C Using user rectangle | "3
(* Using user polygon
i<Step 3» Extract n Delete Node
«Step 4-1» Find route and e line between two node
Circuity [234803 i
«Step 4-2» T-Zone Process
Calculate Circuity z]
Show Circuity Matrix | Show Circuity Resut |
Show Network Connectivity Matrix
Show Network Accessibility Matrix |
{
Figure 7. User interface of application program and
processing steps: <Step 1> Input layers of road
centerline and administrative boundary, <Step
2> Selection of analysis zone, <Step 3>
Automatic extraction of nodes within the
analysis zone, <Step 4-1> Calculation of
circuity value at a node in the analysis zone,
<Step 4-2> Calculation of circuity, connectivity,
and accessibility of the whole nodes in the
analysis zone and their representation in the
matrix form
@ Result Matrix
9 10 11 12 sum circuity ^
0.01997389 000005828 0.00000000 0.63723279 0.74391406 0.06762855
001232630 001744990. 0.00043406 0.60128515 070849000 0.06440818
000505501 0010832892 0.03529893 0.73416899 0.83107586 007555235
001027441 0.01402302 000423306 072902473 0.76498138 0.06954376
0.00000000 000529661 0.02038859 0723586665 (0892428287 0.07493481
0.00723497 0.00000001 0.00031508 0.73739551 0.81738464 0.07430763
000000000 0.00000000 0.03413389 0096914521 1.06417437 0.09674312
Sii 0.00000000 0.00263435 0.92164409 0.96298555 0.08754414 -
4 | "
Figure 8. Processing results of «Step 4-27 in Fig. 7:
Normalized circuity matrix
£1 Network Accessibility matrix A = C1+C
& Circuity Result
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Figure 9. Processing results of «Step 4-2» in Fig. 7:
(Left) Network connectivity matrix for (Ci
(Right) Network accessibility matrix for [A] with
respect to the whole nodes in the analysis zone
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