ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
c. Transformation of the intersection nodes 
d. Transformation of terminal points and text strings 
e. Transformation of arcs 
Step a makes use of conventional TIN generation methods. In 
our experiments we have used the source code provide by 
Shewchuk[2], 
The details of step b to e are as follows. 
(1) Classification of intersection nodes 
With the specified corresponding points of maps and real world 
coordinates, uniformed distorted maps can be rectified by 
triangulating the corresponding points and transform the points 
with the affine parameter obtain from corresponding triangular. In 
the case of cadastral map, the collinear relationship must be 
maintained even during the TIN transformation. Obviously this 
condition can not be satisfied with the above method. 
In order to maintain the collinear relationship, the transformation 
method of intersection points must be chosen according to their 
types. Fig.2 shows some of the intersection types and their 
corresponding transform methods. 
Here, transform methods T1, T2 and T3 are defined as follows: 
T1: Affine transform with the parameter defined by the TIN 
triangle that the node belongs to. 
T2: Helmet transform with parameter defined by the two 
terminals of a transformed collinear group. 
T3: Replacement by the intersection point between collinear 
groups 
(2) . Transformation of intersection points 
The intersection points are transformed in the order of T1, T2 and 
T3 according to their types. 
(3) Transformation of terminal points and text strings 
Since the topology of terminal points must be maintained after 
transformation of intersection points, terminal points are 
transformed by the following procedures: 
(a) Intersection of two line segments 
(b) Intersection of three line segments 
Fig.2 Examples of intersection of various number of line segments and their transformation methods 
a. TIN generation with all the intersection nodes 
b. Find the TIN triangle that includes the terminal point 
c. Calculate the affine transform parameter and transform the 
point 
The origin of text strings will also be transformed in the same 
method. 
(4) Transformation of arcs 
Since in our system, arc is defined by its center, radius, rotation 
matrix, starting angle and sweeping angle, the start point and end 
must be first calculated and transformed. Then the transformed 
arc’s center, radius, rotation matrix, start angle and sweeping 
angle will be reconstructed.