Apparatus and method of generating curved baseline for map labeling
View Patent ↗Apparatus and methods of generating a curved baseline for a map labeling include receiving a polyline P={p 1 ,p 2 , . . . ,p n } of n points, generating a supporting polyline Q={q 1 ,q 2 , . . . , q m } (m≧n) of m points at an expected distance d between polyline P and a curved base line L. A predetermined number of B-Spline points is generated based upon supporting polyline Q. The B-Spline points are then connected to form a curved baseline L for displaying a label.
1. A computer-implemented method of generating a curved baseline for a map labeling, comprising:
receiving by a computing device a polyline P of n points, where P={p 1 ,p 2 , . . . ,p n };
generating with the computing device a supporting polyline Q of m points an expected distance d between P curved base line L, where Q={q 1 ,q 2 , . . . ,q m }(m≧n);
generating with the computing device a predetermined number of B-Spline points based upon supporting polyline Q; and
outputting with the computing device the generated B-Spline points.
2. The method of claim 1 , wherein said generating supporting polyline Q further comprises:
generating points {q 1 ,q 2 , . . . ,q m } such that each triangle Δq u q u+1 q u+2 (u=1, 2, . . . ,m−2) is above polyline P and does not touch P.
3. The method of claim 1 , wherein said generating supporting polyline Q further comprises:
generating points {q 1 ,q 2 , . . . ,q m } such that Q satisfies
q
j
q
j
+
1
_
≥
d
·
3
2
(
j
=
1
,
2
,
…
,
m
-
1
)
.
4. The method of claim 2 , wherein said generating supporting polyline Q further comprises:
generating first point q 1 , wherein:
u
=
p
2
-
p
1
p
2
-
p
1
;
vectors w x =d·u y ; w y =−d·u x ; and q 1 =p 1 +w.
5. The method of claim 4 , wherein said generating supporting polyline Q further comprises:
generating last point q m , wherein:
v
=
p
n
-
p
n
-
1
p
n
-
p
n
-
1
;
vectors z x =d·v y , z y =−d·v x ; and q m =p n +z.
6. The method of claim 1 , further comprising connecting the B-Spline points to form a curved baseline L.
7. The method of claim 6 , further comprising using curved baseline L to draw a curved label.
8. At least one processor configured to perform the actions of:
receiving a polyline P of n points, where P={p 1 ,p 2 , . . . ,p n };
generating a supporting polyline Q of m points an expected distance d between P and a curved base line L, where Q={q 1 ,q 2 , . . . ,q m }(m≧n);
generating a predetermined number of B-Spline points based upon supporting polyline Q.
9. A computer-readable medium storing instructions, the instructions causing a computer to perform a method, the method comprising:
receiving a polyline P of n points, where P={p 1 ,p 2 , . . . ,p n };
generating a supporting polyline Q of m points at an expected distance d between P and a curved base line L, where Q={q 1 ,q 2 , . . . ,q m }(m≧n);
generating a predetermined number of B-Spline points based upon supporting polyline Q; and
connecting the B-Spline points in sequence.
10. A portable end user device operable to generate a curved baseline for map labeling, comprising a computer platform further including:
a processor;
a memory executable by the processor, the memory including a curved baseline generator module that includes:
an input of a polyline P of n points, where P={p 1 ,p 2 , . . . ,p n };
logic operable to generate a supporting polyline Q of m points at an expected distance d between P and a curved base line L, where Q={q 1 ,q 2 , . . . ,q m }(m≧n);
logic operable to generate a predetermined number of B-Spline points based upon the generated supporting polyline Q; and
an output comprising the B-Spline points forming the curved baseline L.
11. The device of claim 10 , wherein the portable end user device is a portable GPS device.
12. The device of claim 10 , further comprising a display unit operable to display a label drawn on the curved baseline L.