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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004 tM
: 2 al, s - overshoot
point and first point is less than the predefined Start Active Pen eec
: b
tolerance, then LineString will be closed and, all Command Ao outs
points of LineString will be drawn from DGN buffer < : jeter ie
. N p > /€
and control will go to s 4; :
: Seo ol M go o step | tied anno Get first Data _| Close DGN > Set another extension
iL. If user sends a RESET by P-Cursor, then LineString S Point from P- buffer Search area to wing.
point list will be closed and all of its points from Cursor range box ONG
DGN buffer will be drawn in file and on screen; a a
12. The assigned buffer of DGN will be free now; ^Y Rls
13. Another search area will be defined according to Set search iM
area(R- Tol) objects.
range box of the newly drawn LineString and program
will search in this new criterion area to find
environm
intersected linear features. For each linear feature in re
cs ; LOOP Yes Error T
the new search criteria, program will do these steps:
a. Finds the intersection point(s) between this ^v
(new) element and founded feature and Generate new —
store these points in an array; node(s) on new Duplicat
b. Generates node at each intersection points element objects
of array on the newly created element and
founded linear feature and splits these | No
elements to two elements; Generate new I — ———
14. Program will automatically call the Active Command node(s) on found Short
again, and control will go to step 1 (while user does element objects
not close the program, and while user doesn’t change | ——
the Active Command). Generate new node » Crossing
Figure 2 illustrates flowchart of cleanup module. on found element v objects
3.2 Errors and IPCBS's Solutions Cdi eec Unde
In IPCBS, an errorless automatic cleanup method has organized Snap to vou found sas Oversho
to cover data editing tasks categorized in table 1. element search area(R- Tol
IPCBS program doesn't cover the following errors, because »
some of them just can be corrected after digitization and other « à
ones are optimization tasks rather than critical errors: Y /
I. Converting features with complex geometry (i.e. B- Store in LinString
Spline) to simple one (i.e. LineString); paints list
2. Editing of hydrographical features (editing =~ Clustere
streamlines and ridgelines according to ridges of Y / nodes
contour line); Request another point
3. Best fitting curves (replacing sharp polylines by from P-Cursor Sliver
smooth one); polygon
4. Squaring Angles that are near quadrant angle;
5. Height-point editing according to elevation of its RN Yes
adjacent contours; RESET?
6. Alignment editing (e.g. building features alignment Polygon
error). closure
[Neto, 2
Draw dynamic Pseudo
4. QUALITY OF IPCBS’S OUTPUTS AND ITS Sa line nodes
EFFICIENCY
4.1 Test of IPCBS's Output lg Ignore Danglin
elevation? this point objects
Several tests were carried out on simulated and real data (aerial
photographs) for examining outputs of IPCBS (under Zeiss N | Comple
Planicomp-P33 analytical plotter). After debugging and testing linear
the operation of IPCBS with simulated data, program was objects
installed to be checked by real data. In the main test, two weedin:
photographs were used with the following specifications: S
Camera: WILD 15/4 UAGA-F (Nr 13180)
Focal length: 153.4 mm
Time of imaging: Feb 1994 ‘Table
Region: Tehran Snap to first
Scale: 1:3000
Output file after data reduction using IPCBS was tested in two
famous GIS software, ArcInfo 8.0 and ArcView 3.1. The results
were completely satisfactory. No geometric error (ic.
vertex Cm ST
Figure 2. Flowchart of Cleanup module
394
