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I claim:
1. A method of processing data in different maps in order to display a
designated region of interest for editing, said different maps carrying
different kinds of information of an area, said area being the same area
for each map, each map being sectioned into pages with boundaries between
adjacent pages, comprising the steps of:
establishing positional correspondence between said different maps;
storing data of said different maps into a file memory in the form of
layers wherein each layer comprises the complete data of a different map
and wherein each layer is sectioned into pages;
displaying on a display means a general map of said area, said general map
includes information of said different maps;
designating a region of interest on said general map, said region of
interest may include a plurality of pages for at least one of said
different maps;
transferring data within said designated region of interest on said
different maps stored in said file memory from said file memory to a
temporary memory;
erasing said boundaries between each pair of adjacent pages in said
temporary memory; and
displaying without boundaries a map of said designated region of interest
on said display means for editing.
2. A method according to claim 1, wherein said storing step includes making
tables representing elements corresponding to said data of said different
maps as positioned within each page, said elements including line elements
corresponding to lines between said elements.
3. A method according to claim 2, wherein said erasing step includes
unifying tables of gathered pages and connecting lines defining line
elements disposed adjacent to each other.
4. A method according to claim 1, wherein said designating step includes
designating said region of interest in the display means with a
designating means.
5. A method according to claim 1, wherein said designating step includes
designating said region of interest by inputting numerical data defining
said region of interest.
6. A method according to claim 1, wherein said erasing step includes
gathering data on said each pair of adjacent pages and joining data
related with the same points on the boundaries of the adjacent pages.
7. A method according to claim 1, further comprising the step of editing
data in said map of said designated region of interest.
8. A method according to claim 7, further comprising the steps of dividing
the edited map according to said page boundaries of said different maps,
and storing the edited data on a page-by-page basis.
9. A method of claim 1, further comprising the steps of collecting data in
different layers within said region of interest and displaying the
collected data superposedly on the same map.
10. A method according to claim 7, wherein said data in the file memory are
designated with predetermined priority values, further comprising the step
of displaying data of the same priority level successively in the order of
large to small value.
11. A method of editing maps with the aid of file storage means for storing
different maps carrying different kinds of information of an area, said
area being the same area for each map, each map being arbitrarily
sectioned into pages which constitute a continuous map when adjacent pages
are connected, data for each map being stored on a page-by-page basis,
correlation storage means for storing coordinate correcting values for
rearranging said pages in a continuous manner, and temporary storage means
for storing said data for executing editing processes of the maps,
comprising the steps of:
transferring all map data of the pages successively from said file storage
means, and said coordinate correcting values from said correlation storage
means to said temporary storage means;
obtaining a continuous map by joining together said pages along boundaries
thereof on the basis of said map data and said coordinate correcting
values transferred; and
performing graphic editing processes including displacement, joining, and
separation.
12. A map editing method according to claim 11, wherein said step of
obtaining a continuous map includes erasing lines at the boundaries in the
original pages between two adjacent pages.
13. A map editing method according to claim 11, wherein said step of
obtaining a continuous map includes erasing end points of line segments
located on a boundary of pages when a straight line is produced by joining
said line segments, while when said line segments form an inflection on
the boundary upon being joined, integrating the end points of said line
segments into data of one point defining said inflection.
14. A map editing method according to claim 11, further comprising the step
of dividing said continuous map drawing into sub-areas after having
undergone said edition processing step.
15. A map editing method according to claim 11, further including steps of
inputting a region of interest, and extracting those of said pages of said
map which overlap said region of interest, before said transferring step.
16. A map editing method according to claim 15, wherein plural sets of map
data are available for a map to be retrieved, further including the steps
of extracting the data for these pages overlapping said region of interest
from said data sets; performing coordinate translation for the pages as
read out to allow all relevant data to be displayed in a single coordinate
system.
17. A map editing method according to claim 16, wherein said plural data
sets being previously assigned with predetermined priority levels, further
comprising the step of displaying the relevant data in the order of said
priority levels.
18. A drawing data managing system, comprising;
file storage means for storing data on different maps carrying different
kinds of information of an area, said area being the same area for each
map, each map having an arbitrary selected coordinate system and being
sectioned into a plurality of numbered polygonal shaped pages which
constitute a continuous map when adjacent pages are connected at
boundaries between the pages, the data being stored on a page-by-page
basis;
temporary storage means for temporarily storing data of at least part of
said maps to enable processing of said maps;
processing unit means for executing processing on the data stored in said
temporary storage means;
storage means for storing data servicing for correlating identification
number of each page with its page boundary polygon, relative rotation of
the associated coordinate system and coordinate offset values represented
in a standard coordinate system;
means for extracting data of a first page of a first map from said
extracted file storage means and transferring said data to said temporary
storage means;
means for extracting data of a second page of a second map located in said
area to be at least partially overlapping on said first page of said first
map and determining relative rotation and offset between coordinate
systems of said first and second pages; and
means for compensating the positions of data in said second page so that
correspondence relation can be established between contents of said first
and second pages.
19. A drawing data management system according to claim 18, wherein the map
data of a same region is divided into a plurality of pages of different
varieties having different boundaries, different coordinate systems and
coordinate offset values, and said file storage means also stores such
information on page configurations that correspondence can be established
among a plurality of pages of different varieties concerning said same
region.
20. A drawing data management system according to claim 18, wherein said
compensating means performs correcting processing of map data once
transferred to the temporary storage means to prepare the pages having
predetermined page boundaries, coordinate systems and coordinate offsets
so that correspondence among said pages can be established.
21. A drawing data management system, comprising:
file storage means for storing data of a plurality of maps carrying
different kinds of information about an area, said area being the same for
each map, each map being arbitrarily divided into sub-areas the data being
stored on a sub-area-basis;
input means for inputting map data to be stored in said file storage means;
display means for displaying a map including map data retrieved from said
file storage means;
operation input means for inputting editorial processing of the map data;
coordinate input means for designating coordinates in said map to be
subjected to editorial processing;
temporary storage means for temporarily storing drawing data to enable
processing of the map data;
processor unit means for executing the editorial processing at said
coordinates designated by said coordinate input means; and
means for displaying marks indicating availability of stored data for each
of said sub-areas, in superposition on said map displayed by said display
means.
22. A drawing data management system according to claim 21, further
comprising means for transferring available map data for sub-areas
relating to at least partially overlapping a designated area through said
coordinate input means from said file storage means to said temporary
storage means, for executing information processing.
23. A drawing data management system according to claim 22, wherein in case
data is unavailable in said file storage means for the sub-area relating
to the designated coverage and pattern element, said processor unit means
commands to transfer data from said file storage means to said temporary
storage means for a corresponding sub-area relating to the same pattern
element and having different reduced scale, if available, for said
unavailable data.
24. A drawing display system, comprising:
file storage means for storing data of different maps of an area, assigned
with priority levels, the maps including maps carrying different kinds of
information, each map being arbitrarily sectioned into a plurality of
pages which would constitute a continuous map when adjacent pages are
connected at boundaries;
display means for displaying said data of said different maps;
operation input means for inputting requests for the display of said data
of different maps;
temporary storage means for temporarily storing said data of said different
maps to enable processing of the data of said maps; and
processing unit means for executing the processing, wherein said maps are
displayed on said display means in the order of said priority levels.
25. A drawing display system according to claim 24, wherein said processing
unit means discriminates and allows display of only map data having
respective priority levels exceeding a predetermined value.
26. A drawing display system according to claim 24, wherein said processing
unit means has criteria for discriminating whether said map data displayed
are widely distributed over an area which includes said map data being
displayed and making decisions as to whether said criteria is exceeded or
not and whether the amount of displayed map data has exceeded a
predetermined level at the end of each stage of displaying map data having
a certain priority level, to thereby stop subsequent display of map data
having lower priority levels. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention generally relates to graphic data processing. More
particularly, the invention concerns an improvement on or relating to a
method and system for processing wide varieties of graphic or pattern data
which are divided into pages.
DESCRIPTION OF THE PRIOR ART
As a method of preparing a data base of map data which cover intrinsically
extensive space, it has heretofore been known to divide the map data into
pages for storage and management. This known system is advantageous in
that only the data regions required for retrieval, display, edition or the
like may be extracted and loaded into a memory of a computer system.
Also, reading of broken lines or superposed lines has been proposed in U.S.
Pat. Nos. 4,428,077 and 4,550,434.
However, no proposal has been made for a system which is capable of
executing various functions such as retrieval, display, editing and the
like on the graphic or map data stored over and across a large number of
pages without regard to the page boundaries.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a graphic data processing
system which is capable of utilizing, preparing and editing map and/or
drawing data stored among a large number of pages in the divided state.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view illustrating pictorically a
structure of a data base in which a plurality of map data having different
characteristics are stored and divided into pages;
FIG. 2a is a schematic block diagram showing a general arrangement of a
system for processing map data;
FIG. 2b is a flow chart for illustrating briefly a whole procedure of
edition according to an embodiment of the invention;
FIGS. 3a1 to 3a4 are views illustrating pages of a map, FIGS. 3b1 to 3b4
show face tables, FIGS. 3c1 to 3c4 show line tables, and FIGS. 3d1 to 3d4
show point tables, which data tables are stored in a file equipment;
FIG. 4 is a view showing a table of data for establishing correspondences
between pages and a standard or reference coordinate system;
FIG. 5 is a view showing a map for illustrating a procedure for
establishing correspondence between pages having different boundaries and
coordinate systems;
FIG. 6 is a flow chart illustrating the procedure for finding overlapping
relation;
FIGS. 7a to 7c are views showing examples of map display indicating
availability status of various map data;
FIG. 8 is a view showing a management table for indicating varieties and
availability of data concerning various subject matters, scales and
others;
FIG. 9 is a view showing a page shape or geometry storage table in which
page identification numbers are listed together with coordinate values
defining the page geometry or shape;
FIG. 10 is a view showing a display mark management table indicating
contents or instructions, display textures and display colors of
designating marks;
FIG. 11 is a view showing a flow chart illustrating a procedure for
preparing the available data status management table shown in FIG. 8;
FIG. 12 is a view similar to FIGS. 7a to 7c except that the page boundary
shape is of an irregular polygon;
FIG. 13 is a view similar to FIGS. 7a to 7c for illustrating a procedure
for transferring map data from a file equipment to a temporary memory
shown in FIG. 2a;
FIG. 14 is a schematic diagram for illustrating relation between two
coordinate systems of overlapping pages;
FIG. 15 is a view for illustrating a procedure for extracting only those
data belonging to a designated or requested page;
FIG. 16 is a view for illustrating correspondence between page boundaries
between different topographical map layers;
FIG. 17 is a view showing a data table which can be consulted for
controlling the order of display according to which map data are
displayed;
FIGS. 18a, 18b and 18c are views for illustrating a display procedure for
generating display in an ordered manner;
FIG. 19 is a view for illustrating control of image quality or density of
display in a map to be displayed;
FIGS. 20 and 21 are views showing a subject component management table and
a display attributes table consulted in executing the display procedure
illustrated in FIG. 18;
FIG. 22 is a view for illustrating the order in which data are retrieved in
executing the display procedure;
FIG. 23 is a view for illustrating an editing procedure;
FIG. 24 is a view showing a page offset management table which is consulted
in executing the editing procedure;
FIG. 25 is a view for illustrating an area subjected to editing;
FIGS. 26a, 26b, 26c and 26d are views for illustrating a procedure for
interconnecting four pages to constitute a single drawing together with
associated data;
FIGS. 27a to 27d are views for illustrating an integrated drawing resulting
from the page-connecting procedure together with relevant graphic data;
FIG. 28 is a view for illustrating the editing step 103 shown in FIG. 23;
FIGS. 29a, 29b1 to 29b3 are views for illustrating procedure of re-division
of an edited drawing into four pages together with associated data tables;
FIGS. 30a, 30b1 to 30b4 are views showing graphic data table employed in
the re-division procedure; and
FIG. 31a1 to 31a4 are views showing face data table for the pages resulting
from the re-division procedure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, exemplary embodiments of the invention will be described
by referring to the accompanying drawings.
A system structure for executing various processes is illustrated in FIG.
2a. In the figure, a reference numeral 200 denotes a central processing
unit or CPU, a numeral 201 denotes a file equipment for storing drawing or
map data as well as graphic (or pattern) and character data which are
divided into pages and classified in dependence on characteristic features
of the map data such as reduced scale, varieties of subject matters and
the like thereof, a numeral 202 denotes a temporary memory for allowing
executing of processings such as edition or the like to the map or drawing
data, a numeral 203 denotes a CRT (cathode ray tube) display for
displaying drawing or map data as well as the other data, a numeral 204
denotes a keyboard, numerals 205 and 206 denote, respectively, a tablet
and a stylus for designating locations subjected to editing, and a numeral
207 denotes a drawing data input device for fetching the drawing or map
data in terms of image data for vector analysis to derive coordinate data.
For more particulars of the system shown in FIG. 2a, reference is made to
an article entitled "Automatic Recognition of Design Drawings and Maps" by
Ejiri et al, IEEE 7th International Conference on Pattern Recognition
(1984) Montreal Canada (p.p. 1296-1305). Reading and editing drawing data
are also proposed by Shimada et al in U.S. Pat. No. 4,428,077 and U.S.
Pat. No. 4,550,434, which are hereby incorporated by reference. Procedures
as well as operations described below are performed with the aid of the
system outlined above.
Before entering into detailed description, the basic concept of the
invention will be first outlined by referring to a flow chart shown in
FIG. 2b. It is known that one and the same district may have a number of
maps which differ from one another in respect to the scale, the subject
matter (e.g. geomorphological map, piping diagram, power transmission and
utilization system diagram, etc.) and others. Accordingly, in order to
store the map data in a file equipment in correlated state, alignment of
coordinate systems, determination of offset values relative to a reference
coordinate system, establishment of correspondences among various
parameters and the like processings are first performed (step 1010). Next,
it is checked whether data for a region which is subjected to editing is
available or not. To this end, a general map covering the region of
concern is displayed on a CRT, which is followed by superposed display of
marks indicative of data availability at a designated scale and subject
matter (step 1020). A portion in the region for which desired data is
found available and which is to be extracted for editing is indicated by
using a tablet and a stylus, whereby data for that portion is extracted
from the file equipment and transferred to a temporary memory (step 1030).
The content of the temporary memory is displayed on the CRT to determine
whether the data extracted from the file is relevant to the portion
subjected to the editing. To this end, data elements are assigned with
priority values and the elements are displayed in the order of high to low
priority levels (step 1040). The series of processing steps described
above is repeated until the display coincide with the contents requested
for editing (step 1050). Since the data base transferred to the temporary
memory is divided along the page boundaries, joining processing is
executed to make linear portions continuous (step 1060). Then, processing
for editing such as addition, deletion, displacement and the like are
performed on the continuously joined data (step 1070). After the editing
processes have been completed, the data present in the temporary memory is
again divided along the page boundaries to be stored in the file equipment
(step 1080).
Now, referring to FIG. 1, description will be made on a data structure in
which drawing or map data can be stored on the page basis (i.e. data are
divided into pages to be stored). FIG. 1 shows conceptionally an
inter-page relationship in the case where each of drawings differing one
another in respect to the reduction scale, map components or the like are
divided into parts referred to as page for the purpose of facilitating
data management. In the figure, x and y represent coordinate axes for
indicating a two dimensional extent of a drawing or map. It will further
be noted that the map is classified into a plurality of component map
layers A, B, C and D in dependence on the subject matters and other
factors. By way of example, the map layer A corresponds to a topographical
or geomorphological map of a reduced scale of 1/10000, the layer B
corresponds to the topographical map the reduced scale of which is 1/2500,
the layer C corresponds to a map showing institutes, facilities and the
like (hereinafter referred to as the facilities map), and the layer D
corresponds to a partition map showing a block, section, boundaries or the
like. The component maps are separately arrayed along the Z-axis. In
conjunction with the map data structure shown in FIG. 1, a map reference
position varies in dependence on the layers even in the case of the
topographical maps concerning an identical region or district if the
scales thereof differs from each other, as is the case with the map layers
A and B. As a consequence, the page boundaries of one topographical map
(e.g. map layer A) does not always coincide with those of another
component map (e.g. map layer B) even when the ratio of scales between
both of the maps A and B can be represented by an integer. Further, when
the contents of a component map differ from those of others (as is the
case with the facilities map C with respect to maps A and B), the page
boundaries thereof do not always extend in parallel with those of other
maps, since the map C is provided with a coordinate system dedicated
thereto for the purpose of facilitating the facilities data management,
which coordinate system differs from those of the map layers A and B.
Besides, the page boundary profile do not necessarily assume a rectangular
form but may take an irregular polygonal form, as is the case of the map
layer D.
The graphic or map data in each page is stored in a manner mentioned below.
The map data for every page which are illustrated in FIGS. 3a1, 3a2, 3a3
and 3a4 are transformed through the map data input device 207 shown in
FIG. 2a or through manipulation of the stylus 206 relative to the tablet
205 into face tables as shown in FIGS. 3b1, 3b2, 3b3 and 3b4, line tables
as shown in FIGS. 3c1, 3c2, 3c3 and 3c4 and point tables as shown in FIGS.
3d1, 3d2, 3d3 and 3d4 with the aid of the coordinate systems (x.sub.1,
O.sub.1, y.sub.1), (x.sub.2, O.sub.2, y.sub.2), (x.sub.3, O.sub.3,
y.sub.3) and (x.sub.4, O.sub.4, y.sub.4) dedicated to the maps, as
illustrated in FIGS. 3a1, 3a2, 3a3 and 3a4, respectively, wherein O.sub.1,
O.sub.2, O.sub.3 and O.sub.4 represent the origins, respectively. The
resulting various tables are then stored in the file equipment 201. By way
of example, let's consider the drawing or map on a page P01 (FIG. 3a1). It
will be seen that the drawing includes two line elements LN0101 and LN0102
and a single area or face element FC0101. It will further be seen from the
face table of FIG. 3b1, "FACE-TABLE-01", that the face FC0101 is defined
by a pair of lines LN0103 and LN0104. In conjunction with the contents of
the face table "FACE-TABLE-01", it should be mentioned that data listed in
the column L-ORDER give the order or sequence to the lines defining the
face, while data "DIRECTION" represents an index designating the direction
of line so that the face can be defined by following the lines clockwise.
More specifically, when the index assumes a value "0", P-ORDER in the line
table of FIG. 3c1 follows the points in the order of small to large
values. On the other hand, when the index is "1", the P-ORDER in the line
table of FIG. 3c1 follows the points in the order of large to small
values. The line table of FIG. 3c1, "LINE-TABLE 01", defines relations
between the points "POINT" constituting each line and the values P-ORDER
which impart the order of sequence to the corresponding points in defining
a line. Finally, the point table of FIG. 3d1, "POINT-TABLE-01", correlate
the points "POINT" with the positional coordinates (X, Y). It should be
noted that the values of X and Y in the point table "POINT-TABLE-01" are
determined with reference to the coordinate system (x, 0, y) independent
of those of the other pages P02, P03 and P04.
With a view to systematically managing the various page boundaries and
coordinate systems, there is prepared a table representing correspondences
between the page boundaries and the coordinate systems, respectively, as
is illustrated in FIG. 4. More specifically, the table of FIG. 4 lists up
relations among the coordinate series defining the page boundary polygons
with reference to a standard coordinate system, relative rotational angles
(also referred to as relative rotations) between the coordinate axes of
the individual pages and those of the standard or reference coordinate
system, and the reference positions of the individual pages in association
with the respective page labels.
For preparing the table shown in FIG. 4, the series of coordinates of the
page boundary polygons can be determined by inputting a drawing indicating
the shape or configuration of the page boundary (also referred to as page
profile) through the drawing input device 207 or by following sequentially
boundaries of a page boundary map placed on the tablet 205 with the stylus
206. On the other hand, the relative rotational angle of each page
coordinate system and the value for correcting the offset of the reference
position on each page relative to the standard coordinate system can be
obtained by displaying on the CRT 203 the axes of the page coordinate
system, positioning the stylus at the page reference position and then
moving the stylus on the page coordinate axes, wherein the coordinate
value requested to be inputted is supplied to the CPU 200 through the
keyboard 204 to read the position of the stylus at that instant. This
procedure is repeated a number of times corresponding to that of pages to
be managed. The resulting data are associated with the corresponding page
labels, respectively, to be subsequently stored in the file equipment 201
in the table format shown in FIG. 4.
Next, description will be made on a method of establishing correspondences
between the pages having boundaries and the coordinate systems differing
from each other with the aid of the table as shown in FIG. 4. For
convenience of description, let's consider a drawing or map illustrated in
FIG. 5. Assuming that correspondences are to be established between the
page boundaries P01, P02, . . . , P12 indicated by solid lines in the map
on one hand and page boundaries VP01, VP02, . . . , VP12 indicated by
dotted broken lines, respectively. It is further assumed that the polygons
representative of the page boundaries are classified into groups in
dependence on the types of the respective maps as indicated by groups a
and b in the table shown in FIG. 4 and stored in a page shape storing
table. On these assumptions, consideration will then be made on
establishing correspondence to the hatched rectangular page VP06 shown in
FIG. 5. It will be seen that the page boundaries P02, P04, P05 and P07 lie
in partially overlapping or superposing relation with the page VP06. At
this point, a procedure for examining the interpage overlapping relation
will be described. The procedure starts from the fact that each side of a
polygon defining a boundary of a page can be defined by the positions of
adjacent apexes in two-coordinate system and the overlapping relation can
be examined by finding whether the sides of the polygons to be checked as
to the partially overlapping relation intersect each other or not. By way
of example, the overlapping relation between the pages VP06 and P05 can be
ascertained by examining the overlapping relation between the polygon
(R.sub.1, R.sub.2, R.sub.3, R.sub.4) defining the page VP06 and the
polygon (V.sub.1, V.sub.2 . . . , V.sub.10) defining the page P05. To this
end, among all the possible combinations of individual sides R.sub.i
R.sub.j (i, j=1-4) and V.sub.m V.sub.n (m, n=1-10) of both the polygons
having the sides (R.sub.1 R.sub.2, R.sub.2 R.sub.3, . . . , R.sub.4
R.sub.1 and (V.sub.1 V.sub.2, V.sub.2 V.sub.3, . . . , V.sub.1 V.sub.10),
respectively, the intersecting relation between both sides R.sub.i R.sub.j
and V.sub.m V.sub.n can be determined through a procedure illustrated in a
flow chart of FIG. 6. Referring to this figure, at a step 100, a flag CF
indicating possibility of intersection is initialized to "0"(CF=0), being
followed by a step 101 where ranges of the coordinate values belonging to
the sides are determined as follows:
(XR.sub.min, XR.sub.max), (YR.sub.min, YR.sub.max) and
(XV.sub.min, XV.sub.max), (YV.sub.min, YV.sub.max).
Then, at step 102, it is examined whether XR.sub.min or XR.sub.max is
located within the range (XV.sub.min, XV.sub.max), or whether YR.sub.min
or YR.sub.max lies within the range (YV.sub.min, YV.sub.max), and also is
examined whether XV.sub.min or XV.sub.max is located within the range
(XR.sub.min, XR.sub.max) or whether YV.sub.min or YV.sub.max lies within
the range (YR.sub.min, YR.sub.max). When the above condition is satisfied,
the possibility flag CF is set to "1"(step 102). Here, the range includes
the end points. In that case, the coordinates of the cross point or
intersection between straight lines R.sub.i R.sub.j and V.sub.m V.sub.n
are determined as (X.sub.c, Y.sub.c) through steps 103 to 105.
Furthermore, when and only when the coordinate value of X.sub.c is located
within the range defined by (XV.sub.min, XV.sub.max) and (XR.sub.min,
XR.sub.max) and also the coordinate value of Y.sub.c is located within the
range defined by (YV.sub.min, YV.sub.max) and (YR.sub.min, YR.sub.max),
then an intersection flag is set. Otherwise non-intersection flag is set
(steps 105-107). The pages enclosed in the overlapping pages may then be
regarded as totally overlapping pages.
Next, description will be directed to a method of indicating definitely the
data availability status to a plurality of system users starting from the
data base management status described above so that the user can know to
what extent the data is available. In general, the procedure resides in
that a general map (also referred to as a frame map) covering the whole
range subjected to management or supervision or edition is displayed on a
CRT together with the page boundaries constituting the managing or
supervising units of the data base, wherein a region which is designated
and data of which is available is displayed in superposition with a
predetermined mark. FIGS. 7a-7c illustrate examples of map frame
structures for examining the availability status of a map data base of a
city A. In the right hand column, there is listed a menu including items
to be checked with regards to the desired matters of the map, while in the
remaining space, a general view of the city A is schematically shown. Now,
description will be made in more detail by referring to FIG. 7a. The
righthand column is allocated to the menu. More specifically, rows 101
indicates varieties or types of subject matter of the map to be checked
such as "Topographical Map", "Power Transmission Lines aod Utilization
System Diagram" or the like. A row 102 indicates the scale of the map, and
rows 103 indicate the type of examination to be made. On the other hand,
the general view of the city A located on the lefthand side indicates that
the city A covers North 1st quarter, North 2nd quarter, East quarter, and
Old Town quarter and others. Broken lines 104 represent page boundaries
when sub-areas or sub-regions are defined as pages in dependence on the
subject matter or the scale. Dotted broken lines 105 represent the
boundary of the city and the boundaries between the quarters or towns.
Reference numeral 106 denote displays of geographical designations on the
general view of the city A. A reference numeral 107 denotes a marker which
indicates a range of the items which are designated by the user and for
which data are available from the data base. The marker 107 is constituted
by a hatched rectangle in the case of the illustrated example. Reference
numerals 108 indicate markers for indicating the items in the menu as
designated or requested. Each marker 108 is also constituted by a hatched
rectangle. With the map frame structure described above, there is shown in
FIG. 7a the range of available data with which the topographical map can
be displayed at the reduced scale of 1/2500, wherein the range in concern
is indicated on the map of the city A by the markers 106 (hatched areas).
Similarly, in FIG. 7b, the markers 106 indicates the range of available
data with which the topographical map can be displayed at the reduced
scale of 1/1000. In order to indicate the page boundaries and the range
which can be displayed at the designated or requested scale even for the
identical topographical map, there is prepared a page list (TM25006,
TM25007, . . . , TM25027) which satisfies the conditions that the reduced
scale is "1/2500", the subject matter is "topographical map" and that the
content or sort of examination to be made is "display" on the basis of an
available data management table shown in FIG. 8. Subsequently, a list of
coordinate values corresponding to the page numbers, respectively, is
prepared for each of the elements of the page list on the basis of a page
shape storage table shown in FIG. 9. It should be mentioned that the table
shown in FIG. 9 can be prepared through partial extraction of the data
listed in the columns labelled "Page" and "Apexes of Page Boundary
Polygon" n the table shown in FIG. 4. The inner space of a polygon defined
by given coordinate values of apexes as shown in FIG. 9 is applied wit | | |
