JP2011065571A - Graphic display method and graphic display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the amount of data for graphic display corresponding to a plurality of scales, to suppress computational complexity in displaying a rough graphic, and to display the rough graphic whose shape is not so different from a detail graphic. <P>SOLUTION: A recording part 110 records one or more pieces of display graphic data including: a coordinate data string composed by continuously arranging coordinate data of a plurality of vertexes to be required for drawing the detailed shape of the graphic at a first scale that is the maximum scale; and coordinate reference data for specifying the coordinate data of the plurality of vertexes to be required for drawing the rough shapes of the graphics by one or more scales that are less than the maximum scale, from the coordinate data string in accordance with the second scale. A conversion part 130 generates a rough coordinate data group where the coordinate values of the coordinate data group, which are constituted of only the second coordinate data specified from the coordinate data string in the display graphic data in accordance with the designated scale, are corrected into the coordinate system of the designated scale through the use of the coordinate reference data in the display graphic data read from the recording part 110. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a graphic display method and a graphic display device, and more particularly to a graphic display method and a graphic display device for displaying a graphic such as a map on a screen.

  In a graphic display device such as a car navigation system that displays graphic data to be regarded as a map on the screen, when a graphic showing the same road or area is displayed in a wide range according to the scale, the user can display a schematic graphic. It is necessary to display in a shape different from the original detailed figure for easy viewing.

  In order to satisfy this requirement, the following two methods are usually conceivable when displaying a schematic figure.

  As a first method, prepare only the coordinate data string necessary for drawing the most detailed figure, and coordinate value division, coordinate decimation and interpolation coordinates for the coordinate data string according to the specified display scale. A method is conceivable in which calculation / correction processing such as addition is performed and a coordinate data string for a schematic graphic is generated each time. However, in this method, when a relatively simple calculation / correction process is performed, there are cases where the shape of the detailed figure and the outline figure are greatly different (a shape that is close to a circle in the detailed figure becomes a triangle in the outline figure). This misleads the user who sees this display screen.

  In order to solve this problem, a map data generation method is known in which a coordinate data string for a rough graphic is generated from a coordinate data string for a detailed graphic based on various thinning conditions (for example, see Patent Document 1). ). In the map data generation method described in Patent Document 1, a target vertex is selected from vertices constituting a detailed polygon that can display a detailed shape prepared for an enlarged view, and the target vertex and the relative adjacent vertex are relative to each other. When a predetermined parameter representing the positional relationship satisfies a predetermined thinning condition, a target polygon is generated by deleting the target vertex to generate a schematic polygon.

  Next, as a second method, a method of preparing a coordinate data string necessary for drawing a graphic for each scale, and selecting and displaying a coordinate data string to be used according to a designated display scale can be considered.

JP 2007-256402 A

  However, the method described in Patent Document 1 requires a complicated calculation / correction process, which increases the amount of calculation, thereby reducing the display processing speed.

  On the other hand, the second method solves the problem caused by the first method, but a plurality of coordinate data strings necessary for drawing a figure for each scale must be prepared for each scale. There is a problem of becoming enormous.

  The present invention has been made in view of the above points, and suppresses the data amount of graphic display data corresponding to a plurality of scale displays, and also suppresses the calculation amount of the schematic graphic display, and the detailed graphic and the shape are different from each other. An object of the present invention is to provide a graphic display method and a graphic display device for displaying a schematic graphic that is not performed.

In order to achieve the above object, a graphic display method of the present invention includes a first step of designating a display scale of a graphic to be displayed from a plurality of predetermined display scales, and a first display scale that is maximum. The coordinate data string in which the first coordinate data, which is the coordinate data of a plurality of vertices necessary for drawing the detailed shape of the display scale figure, is continuously arranged, and one or more first scale data whose display scale is less than the maximum. The second coordinate data, which is coordinate data of one or more vertices necessary for drawing the approximate shape of the figure of the display scale of 2, and which is included in the first coordinate data, is 1 From the recording unit in which one or more pieces of display graphic data having coordinate reference data for specifying from the coordinate data string corresponding to each of two or more second display scales are recorded, an arbitrary 1 One second display scale is designated display scale The display graphic data is read out when specified as, and only the second coordinate data corresponding to the specified display scale is selected from the coordinate data string in the display graphic data by the coordinate reference data corresponding to the specified display scale in the display graphic data. A second step of specifying a coordinate data group to be configured; and a second step of generating a rough coordinate data group in which each coordinate value of the coordinate data group specified in the second step is corrected to a coordinate system of a designated display scale. Step 3 and the generated approximate coordinate data group are stored in the storage unit, and then, based on the approximate coordinate data group acquired from the storage unit, the schematic shape of the figure is drawn and displayed on the display unit at the designated display scale. And a fourth step.

  In order to achieve the above object, the graphic display device of the present invention includes an input means for designating a display scale of a graphic to be displayed from a plurality of predetermined display scales, and a first display scale that is the maximum. The coordinate data string in which the first coordinate data, which is the coordinate data of a plurality of vertices necessary for drawing the detailed shape of the display scale figure, is continuously arranged, and one or more first scale data whose display scale is less than the maximum. The second coordinate data, which is coordinate data of one or more vertices necessary for drawing the approximate shape of the figure of the display scale of 2, and which is included in the first coordinate data, is 1 Recording means in which one or more display graphic data having coordinate reference data for specifying from the coordinate data string corresponding to each of two or more second display scales are recorded, and any one first 2 display scale is designated display scale The second coordinate data specified from the coordinate data string in the display graphic data according to the specified display scale by the coordinate reference data corresponding to the specified display scale in the display graphic data read from the recording means when specified. Conversion means for generating approximate coordinate data groups obtained by correcting each coordinate value of the coordinate data group consisting of only the coordinate system of the designated display scale, storage means for storing the approximate coordinate data group, and an outline from the storage means The image processing apparatus includes a drawing unit that acquires a coordinate data group and draws and displays a schematic shape of the figure on a display unit at a specified display scale.

  Here, the coordinate reference data is a bit flag corresponding to the arrangement order of the first coordinate data from one or more first coordinate data constituting the coordinate data string for each second display scale. In this case, the second coordinate data may be constituted by a flag string that specifies the second coordinate data.

  Further, the coordinate reference data is designated and displayed by a bit flag corresponding to the arrangement order of the coordinate data from the coordinate data of the first or second display scale having a one-step display scale larger than the designated display scale. You may make it comprise the flag row | line | column which specifies the 2nd coordinate data of a reduced scale.

  According to the present invention, the data amount of graphic display data corresponding to a plurality of scale displays is suppressed, the calculation amount of the schematic graphic display is also suppressed, and the schematic graphic whose shape does not deviate from the detailed graphic is displayed. Can do.

It is a block diagram of one embodiment of a graphic display device of the present invention. It is a figure which shows an example regarding the level structure and block structure of the display figure data in this invention. It is a figure which shows explanatory drawing of an example of the coordinate calculation of the same position between levels in this invention. It is a figure which shows an example of the level management table, block management table, and figure table in the figure display data used by this invention. It is a figure which shows an example of the correspondence of the figure record in the figure display data used by this invention, the coordinate data sequence table corresponding to this, and a flag sequence table. It is a figure which shows explanatory drawing of an example of the figure drawing using the coordinate data row | line | column and flag row | line | column in embodiment of this invention. It is a flowchart for operation | movement description of one Embodiment of the figure display apparatus and figure display method of this invention.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a block diagram of an embodiment of a graphic display device according to the present invention. In the figure, the graphic display device 100 according to the present embodiment includes a recording unit 110, a reading unit 120, a conversion unit 130, an input unit 140, a storage unit 150, a drawing unit 160, and a display unit 170.

  The recording unit 110 stores display graphic data having information on one or more display graphics. The reading unit 120 reads display graphic data from the recording unit 110 in response to a request from the conversion unit 130 and temporarily stores the display graphic data.

  Based on the content notified from the input unit 140, the conversion unit 130 specifies a graphic to be displayed from the display graphic data held by the reading unit 120, and outputs coordinate data for one or more graphics to the storage unit 150. To do. At this time, the conversion unit 130 issues a drawing start command to the drawing unit 160 when the coordinate data for all the display target graphics is output to the storage unit 150.

  The input unit 140 designates a display scale and a display range to the conversion unit 130 from the outside of the graphic display device 100. The storage unit 150 temporarily stores one or more coordinate data output from the conversion unit 130. The drawing unit 160 draws a display target graphic on the display unit 170 using one or more coordinate data stored in the storage unit 150 simultaneously with the reception of the drawing start command notified from the conversion unit 130. The display unit 170 displays the graphic drawn by the drawing unit 160.

  Next, display graphic data recorded in the recording unit 110 will be described.

  The display graphic data recorded in the recording unit 110 has a hierarchical structure for each scale. Hereinafter, this hierarchy is referred to as a level. The maximum scale (maximum expansion) is level 0, and the level value is increased by “1” as the scale is reduced, such as level 1 and level 2. The lower the level is, the lower the level is. The further away from the level, level 0, the higher level is called. Therefore, the lowest level is level 0.

  In the display graphic data, each graphic is managed for each divided area called a block obtained by dividing the display range with the same coordinate size.

  For example, consider a case where a map is displayed at a plurality of scales on the display unit 170 with a certain fixed resolution (coordinate size). In general, the higher the level, the smaller the drawing scale of buildings, roads, etc., and a wide geographical area is displayed. On the other hand, the lower the level, the larger the figure drawing scale of buildings, passages, etc., and geographically narrow range is displayed.

  However, the geographical range (display range) of the upper level and the lower level is the same. However, since it is necessary to draw the detailed shape of the graphic as the lower level, the lower level requires a larger coordinate width than the upper level with respect to the same geographical range, and as a result, the data amount increases as the lower level.

  Considering the cache memory capacity limitation of the graphic display device 100, it is necessary to limit the amount of data read from the recording unit 110 to a certain size regardless of the level. Therefore, a divided area unit called a block is used.

  FIG. 2 shows an example regarding the level structure and block structure of the display graphic data. FIG. 2A shows the relationship between the display range of level 0 and the coordinate size of each block, and one display range is composed of 16 blocks. FIG. 2B shows the relationship between the display range of level 1 and the coordinate size of each block, and one display range is composed of four blocks. The level 1 figure is a figure obtained by reducing the level 0 figure by half. FIG. 2C shows the relationship between the display range of level 2 and the coordinate size of each block, and one display range is composed of one block. The level 2 figure is a figure obtained by reducing the level 1 figure to 1/2.

  As shown in FIGS. 2A to 2C, the size of one block is the same regardless of the level, with the horizontal size being X and the vertical size being Y. Further, the total display range of each block is the same regardless of the level.

  That is, in the display graphic data, the display area of the block of level L (L is an integer of 0 or more) is divided into N blocks of 1 block of level L + 1 in the vertical and horizontal directions (N is an integer of 2 or more). Corresponds to the divided area. Therefore, the display area of the block is subdivided as the lower level. In FIG. 2, for simplicity of explanation, the number of levels is “3”, the number of divided blocks N of each level is “2”, and the horizontal and vertical coordinate sizes of each block are (X, Y). It is said. However, there is no problem even if the number of block divisions N and the coordinate size of one block differ between the levels.

  In order to uniquely identify a block at each level, each block is assigned a sequential block number that increases by 1 from 0. This block number is indicated by a numerical value in each block in FIG. 2, and is given priority in the horizontal direction from the lower leftmost block to the uppermost right block, and the N × N level L constituting the same area as one block of level L + 1. A serial number is assigned to a block group.

  When the block number allocation rule as described above is applied, the block number group {BIDs (L)} of the level L block group constituting the same area as the level L + 1 block (block number BID (L + 1)) is expressed by the following equation: Can be derived.

For example, the block number group {BIDs (0)} of the block of level 0 constituting the same area as the block of block number 3 of level 1 (BID (L + 1) = 3) can be specified by the following equation from equation A: .

{BIDs (0)} = {3 * (2 * 2), 3 * (2 * 2) +1, ..., (3 + 1) * (2 * 2) -1)}
= {12,13,14,15}
Further, when the display scale is changed on a map or the like, it is necessary to convert the vertex coordinate value of each display figure in accordance with the display scale and to display the figure shape in an enlarged or reduced manner. That is, it is necessary to calculate the block number of the level L + 1 where the same position as the in-block coordinates of the block with the level L exists and the coordinates in the block.

  In the level structure / block structure described above, the block number BID (L + 1) of the second block of level L + 1 corresponding to the first block indicated by the block number BID (L) of level L and the first block The in-block coordinates (px0, qy0) of the second block corresponding to the left lowermost coordinates (0,0) are derived by the following equation.

BID (L + 1) = BID (L) / (N * N) (Formula B)
(px0, qy0) = ((BID (L)% N) * X / N, (BID (L + 1) / N) * (Y / N)) (Formula C)
However, in the formulas B and C, “A * B” is a multiplication of A and B, “A / B” is a value obtained by dividing A by B (an integer rounded down after the decimal point), and “A% B” is A Represents a remainder (integer) obtained by dividing B by B.

  Furthermore, the intra-block coordinates (px, qy) of the block number BID (L + 1) of the level L + 1 corresponding to the intra-block coordinates (x, y) of the block number BID (L) of level L are given by Calculated.

(Px, qy) = (px0 + (x / N), qy0 + (y / N)) (Formula D)
FIG. 3 is an explanatory diagram illustrating an example of calculating coordinates at the same position between levels. FIG. 3 is an example based on the level structure and block structure shown in FIG. 2, and the level 1 block number BID corresponding to the in-block coordinates (x, y) at the level 0 block number BID (0) = 15. An example of calculating the in-block coordinates (px, qy) of (1) is shown.

  First, the level 1 block number BID (1) corresponding to the level 0 block number BID (0) = 15 is calculated as “3” based on the equation (B).

  Next, the in-block coordinates (px0, qy0) of the block number BID (1) = 3 of the level 1 corresponding to the lower leftmost coordinate (0,0) of the block of the level 0 block number BID (0) = 15 Based on the formula C, the following is calculated.

(px0, qy0) = ((BID (0)% 2) * X / 2, (BID (1) / 2) * (Y / 2)) = (X / 2, Y / 2)
Finally, by using the formula D, the block in the block of the level 1 block number BID (1) corresponding to the in-block coordinates (x, y) of the block of the level 0 block number BID (0) = 15 The coordinates (px, qy) are calculated as follows.

(px, qy) = (px0 + (x / 2), qy0 + (y / 2))
By repeating this calculation, it is possible to specify higher level blocks and in-block coordinates.

  As described above, in the level structure / block structure employed in the present embodiment, it is possible to display the enlarged / reduced figure according to an arbitrary scale by using Expressions A to D.

  Next, an example of the logical structure of graphic display data used in the graphic display device according to the present invention will be described with reference to FIGS.

  The display graphic data recorded in the recording unit 110 includes a level management table, a block management table, a graphic table, a coordinate data string table, and a flag string table. FIG. 4 shows an example of the level management table, block management table, and graphic table.

  As shown in FIG. 4, the level management table 201 has information for managing the level configuration and the block configuration of each level, and includes level management records 211 corresponding to the number of levels. The level management record 211 has a scale ratio between each level and the lowest level, and the number of blocks in each level. Further, although the level management table 201 or the level management record 211 is not shown in FIG. 4, the block management table 202, the graphic table 203, and the coordinate data string table 204 and flag string shown in FIG. Information that can specify the recording area of the table 205 is held.

  Also, as shown in FIG. 4, the block management table 202 stores block management records 212 corresponding to the number N0 of blocks at the lowest level (level 0) in ascending order of block numbers. The block management record 212 holds reference information (graphic record start position and number of graphic records) to the graphic record 213 corresponding to the graphic displayed in each block at the lowest level (level 0) for each display highest level. Here, the “display top level” indicates the top level at which a graphic is displayed.

  The “graphics at the highest display level L” is a graphic that needs to be drawn for display at each level from level L to level 0 (lowest level). Specifically, when a map is displayed in a reduced scale (displayed at a higher level), a facility with a large area such as a large park is displayed, but a facility with a small area such as a house is not displayed. In this case, the graphic display of a facility with a larger area has a higher display top level, and the graphic display of a facility with a smaller area has a lower display minimum level.

  Further, as shown in FIG. 4, the graphic table 203 continuously stores graphic records 213 having a one-to-one relationship with each display graphic. The graphic table 203 continuously stores graphic records 213 in descending order of display top level (in order from the upper level to the lower level) for each block at the lowest level.

  FIG. 5 shows an example of the correspondence relationship between the graphic record, the corresponding coordinate data string table, and the flag string table. In FIG. 5, a graphic record 213 is the graphic record 213 shown in FIG. 4, and a coordinate data string and a flag string used for displaying a schematic graphic at each level are obtained from the coordinate data string table 204 and the flag string table 205. Has information to identify. As this information, the head coordinate data position PP indicated by 214 in FIG. 5, the number of coordinate data NXY (F) referred to by this graphic record indicated by 215, the flag string start position PB 2 (PB 1) for each display level indicated by 216, and There are a number of flags NFLG (a, b) and the like. The number of flags NFLG (a, b) is the number of flags of display level b referred to by the graphic record a. Note that the graphic record 213 shown in FIG.

  The coordinate data string table 204 stores coordinate data of one or more vertices used for detailed graphic display, that is, display at the lowest level, as a coordinate data string for each graphic and successively in the drawing order of each graphic. To do.

  The flag string table 205 stores one or more flag strings of flag FLG that specifies vertex coordinate data necessary for displaying (drawing) a schematic graphic at each display level of a certain graphic from the coordinate data string. Here, as shown in FIG. 5, a coordinate data string referred to by a certain graphic record F is expressed as XYs [F]. Further, the number of coordinate data of XYs [F] is expressed as NXY (F), and the constituent coordinate data group is expressed as XY (F, 0) to XY (F, NXY (F) -1).

  Further, a flag string used for a schematic graphic of level L specified by the graphic record F is expressed as FLGs [F, L] as shown in FIG. The number of flags in the flag row FLGs [F, L] is the number of coordinate data, that is, NXY (F), and the configuration flag group is FLG (F, L, 0),..., FLG (F, L, NXY). (F) -1). As described above, the flag string FLGs [F, L] is coordinate reference data for specifying the coordinate data of the vertices necessary for drawing the schematic shape of the level L graphic.

  Next, an example of graphic drawing using the coordinate data string and the flag string in the present embodiment will be described with reference to FIG. FIG. 6 is an explanatory diagram illustrating an example of drawing a figure using the coordinate data string and the flag string in the present embodiment. The example of FIG. 6 is an example based on the level structure and the block structure shown in FIG.

  It is assumed that a certain figure F is displayed in a block 301 having a block number BID (0) = 15 at level 0 as shown in FIG. As shown in FIG. 6, in block 301, this figure F is coordinate data XY (F, 0) (= 5 vertices) which is all coordinate data of the coordinate data string XYs (F) of figure F at level 0. (X0, y0)), XY (F, 1) (= (x1, y1)), XY (F, 2) (= (x2, y2)), XY (F, 3) (= (x3, y3) ), XY (F, 4) (= (x4, y4)) are sequentially drawn and connected.

  At the time of drawing the figure F at the level 1, drawing is performed using only the coordinate data determined to be necessary by the flag string FLGs (F, 1) of the level 1 in the coordinate data string XYs (F). That is, for example, when the flag FLG (F, 1, i) in the flag string FLGs (F, 1) is “1”, the coordinate data XY (F, i) is determined as the coordinate data necessary for drawing, When the flag FLG (F, 1, i) is “0”, the coordinate data XY (F, i) is determined as coordinate data not used for drawing (where i is 0 to NXY (F) −1). integer). Then, only the coordinate data group determined to be necessary is converted into coordinate values using the formulas B, C, and D, and a schematic figure corresponding to the level 1 is drawn.

  Here, as shown in FIG. 6, the level 1 figure F has four flags FLG (F, 1, 0) whose value is “1” in the block 302 of the level 1 block number BID (1) = 3. ), FLG (F, 1,1), FLG (F, 1,3), and coordinate data corresponding to FLG (F, 1,4), respectively, obtained by converting the coordinate values using Equations B to D In this figure, the coordinate data (p1, q1), (p2, q2), (p3, q3), and (p4, q4) of the following four vertices are drawn and connected in order.

(p1, q1) = ((x0 / 2) + px, (y0 / 2) + qy)
(p2, q2) = ((x1 / 2) + px, (y1 / 2) + qy)
(p3, q3) = ((x3 / 2) + px, (y3 / 2) + qy)
(p4, q4) = ((x4 / 2) + px, (y4 / 2) + qy)
However, in the above four formulas, px and qy are the x coordinates in the block of the block with the block number BID (1) = 3 which is the same position as the lower left position of the block with the block number BID (0) = 15, The y coordinate is shown.

  At the time of drawing the figure F at the level 2, the coordinate data determined to be necessary by the flag string FLGs (F, 2) of the level 2 in the coordinate data string XYs (F) as in the determination operation at the level 1. Drawing is performed using only. Here, as shown in FIG. 6, the level F figure F has a value “1” in the flag string FLGs (F, 2) in the block 303 of the level 2 block number BID (2) = 0. The following two vertices obtained by converting the coordinate values corresponding to the two flags FLG (F, 2,0) and FLG (F, 2,4), respectively, using Equations B to D The coordinate data (a1, b1) and (a2, b2) are sequentially drawn and connected.

(a1, b1) = ((p1 / 4) + ap, (q1 / 4) + bq)
(a2, b2) = ((p4 / 4) + ap, (q4 / 4) + bq)
However, in the above two formulas, ap and bq are in the block of the block of level 2 block number BID (2) = 0 which is the same position as the lower left position of the block of block number BID (1) = 3. The x and y coordinates are shown.

  The flag strings FLGs (F, 1) and FLGs (F, 2) are coordinate data necessary for drawing a rough graphic at each level from the graphic coordinate data string when generating graphic display data to be recorded in the recording unit 110. Decide. Further, when drawing the figure F at each level, if it is determined that the coordinate data XY (F, i) is necessary, the flag of that level is “1”, and if it is determined that it is not necessary, “0” is set. Is generated and recorded in the recording unit 110.

  As another form of the flag sequence, the number of bits of the display level L + 1 flag sequence for a certain figure is set to the number of bits (1b) of the value “1” in the display level L flag sequence, and the display level L The i-th bit flag of the flag string may be a flag string that determines whether or not the coordinate data indicated by the i-th bit flag that is 1b from the top in the flag string of the display level L-1 is valid. It is done. When the flag string is in this format, the amount of graphic display data can be further suppressed as compared to the former format.

  The method for determining the coordinate data required for drawing the schematic figure for generating the flag string is well known, and therefore detailed description thereof is omitted here. For example, the thinning-out conditions described in Patent Document 1, etc. As described above, it is determined in consideration of the scale ratio between level 0 and other levels and the shape difference between the detailed figures.

  Next, the processing operation of the graphic display device 100 of the present embodiment will be described with reference to FIG.

  FIG. 7 is a flowchart for explaining the operation of the graphic display device and graphic display method according to the embodiment of the present invention. At the start of the processing operation, the reading unit 120 reads the level management table 201 and the block management table 202 in the graphic display data from the recording unit 110 and stores them in a memory (not shown) in the reading unit 120 in advance. Also, an external device or user who designates the display level and block number from the input unit 140 corresponds to the number of levels of graphic display data recorded in the recording unit 110, the scale ratio between each level and the lowest level, and each block. It is assumed that the area range to be known is known.

  First, the input unit 140 designates the level L of the graphic to be displayed on the display unit 170 and the display target block number BID (L) in the conversion unit 130 (step S1). Then, the conversion unit 130 specifies the designated display target block number BID (L) and the block number group BIDs (0) of the lowest-level block (level 0) constituting the same area range (step S2). ). In the specifying process of the block number group BIDs (0), the number of blocks NBs of the block number group BIDs (0) is specified from the content of the level management record 201 corresponding to the level L and the block number BID (L), The block number BID (0) [0] to BID (0) [NBs-1] constituting BIDs (0) is calculated by calculating Formula A every time one level advances from level L to level 0. Is identified.

  Subsequently, the conversion unit 130 initializes the value of the variable i to “0”, and then determines whether the variable i is less than the block number NBs (step S3). The variable i is an integer of 0 or more and less than NBs, but the variable i is initially initialized to “0” as described above and is less than the block number NBs. In this case, the conversion unit 130 subsequently sets the variable lv to the highest level Lmax, and then determines whether or not the variable lv is equal to or higher than the level L (step S4).

  The variable lv is an integer between L and Lmax. Usually, in the first stage, the variable lv set to the highest level Lmax is equal to or higher than the level L. In this case, the conversion unit 130 sends the BID (0) [ The graphic record group Fs (BID (0), [i], lv) at the display highest level lv of i] is read and temporarily stored in the memory in the reading unit 120 (step S5). Hereinafter, the number of figure records constituting the figure record group Fs (BID (0), [i], lv) specified in step S5 is NF, the figure records are F [0],..., F [NF-1]. Is written.

  Subsequently, the conversion unit 130 initializes the value of the variable j to “0”, and then determines whether or not the variable j is less than the figure record number NF (step S6). The variable j is an integer of 0 or more and less than NF. Initially, the variable j is “0” as described above, and is less than the figure record number NF. In this case, the conversion unit 130 sends the coordinate data string XYs (F [j]) corresponding to the graphic record F (j) and the flag string FLGs (F of display level L as coordinate reference data) to the reading unit 120. [j], L) are read out and stored in a memory (not shown) in the conversion unit 130 (step S7).

  In step S7, the conversion unit 130 calculates the coordinate data string XYs from the coordinate data string head position 214, the coordinate data number 215, the flag line head position of the display level L, and the flag number of the graphic record 213 shown in FIG. The coordinate data number NXY of (F [j]), the coordinate data XY [0], ..., XY [NXY-1] constituting the coordinate data string XYs (F [j]), and the flag string FLGs (F Flags FLG [0],..., FLG [NXY-1] constituting [j], L) are specified.

  Subsequently, the conversion unit 130 initializes the value of the variable k to “0”, and then determines whether the variable k is less than the coordinate data number NXY (step S8). The variable k is an integer between 0 and NXY. Initially, the variable k is initialized to “0” as described above and is less than the number of coordinate data NXY. In this case, the conversion unit 130 determines whether or not the value of the flag FLG [k] specified in step S7 is “1” (step S9).

  If the value of the flag FLG [k] is not “1” (that is, “0”), the conversion unit 130 determines that the coordinate data XY [k] is unnecessary coordinate data for displaying the display level L. Then, the value of the variable k is incremented by “1” and the processes of steps S8 and S9 are repeated again. On the other hand, when the conversion unit 130 determines in step S9 that the value of the flag FLG [k] is “1”, the conversion unit 130 determines that the coordinate data XY [k] is coordinate data necessary for display of the display level L. The coordinate data XY [k] is stored in the storage unit 150 (step S10). In this way, the conversion unit 130 repeats the processing of steps S8 to S10 until the value of the variable k becomes equal to the coordinate data number NXY, and is necessary for displaying the display level L among all coordinate data of the coordinate data number NXY. Only coordinate data is stored in the storage unit 150. Note that the storage unit 150 manages the number of coordinate data stored for each graphic.

  When the value of the variable k becomes equal to the coordinate data number NXY, the conversion unit 130 increments the value of the variable j by “1” from step S8, and then proceeds to step S6, where the value of the variable j is again less than the figure record number NF. Determine if it exists. Then, the conversion unit 130 repeats the processes in steps S6 to S10 until it is determined in step S6 that the value of the variable j is equal to the number of graphic records.

  If it is determined in step S6 that the value of variable j is equal to the number of graphic records NF, conversion unit 130 decrements the value of variable lv by “1”, returns to step S4, and variable lv is again greater than or equal to level Lmax. Determine whether or not.

  When the processing in steps S5 to S10 is performed on the block BID (0) [i], it is determined in step S4 that the variable lv is equal to or higher than the level Lmax. Thereby, the conversion unit 130 converts the coordinate values of all the coordinate data XY [0] to XY [NXY-1] constituting the coordinate data string XYs (F [j]) stored in the storage unit 150 in step S10. Then, it is divided by the scale ratio Rm (L) between level L and level 0 (step S11). The scale ratio Rm (L) in step S11 is described in the level management record 211 regarding the level L.

  Then, the converting unit 130 uses the block number BID (L) of the level L corresponding to the lower left end of the block of the block number group BIDs (0) as each coordinate value of the coordinate data group obtained by dividing in step S11. The coordinates in the block are calculated and added (step S12). Here, the coordinate value of the in-block coordinate to be added can be calculated using Expression B and Expression C.

  Following the addition process of step S12, the conversion unit 130 increments the value of the variable i by “1”, returns to step S3, and determines again whether the value of the variable i is less than the block number NBs. Thus, until it is determined in step S3 that the value of the variable i is equal to the block number NBs of the block number group BIDs (0), the processing in steps S4 to S12 is performed from the highest level Lmax of the graphic display data to the display level. Up to L is repeated for each display level.

  In step S3, when it is determined that the value of the variable i is equal to the number of blocks NBs of the block number group BIDs (0), the storage unit 150 stores the display target block number BID (L) of the block number group BIDs (0). The coordinate data string of the schematic figure necessary for drawing the block is stored. For this reason, when it is determined in step S3 that the value of the variable i is equal to the block number NBs of the block number group BIDs (0), the conversion unit 130 notifies the drawing unit 160 of a drawing start command (step S3). S13).

  Upon receiving this drawing start command, the drawing unit 160 reads a coordinate data string related to the schematic graphic from the storage unit 150 and starts drawing on the display unit 170.

  By performing the above processing, the graphic display device 100 can perform graphic display of the display target level and block designated from the input unit 140.

  As described above, according to the present embodiment, the coordinate data string table 204 that stores one or more pieces of coordinate data used for detailed display of a figure for each figure and sequentially in the drawing order of each figure, and 1 A flag column table 205 that stores a flag column that specifies coordinate data necessary for a schematic graphic at each display level for each graphic display level from a coordinate data column, with at least one flag, and the most detailed graphic display Sometimes display is performed using all coordinate data in the coordinate data string, and when displaying the rough graphic, only the coordinate data necessary for displaying the rough graphic is used out of the total coordinate data, and the required coordinate data is displayed. Drawing is performed by converting the coordinate values based on a predetermined expression. For this reason, according to the present embodiment, the shape of the detailed graphic and the schematic graphic are not significantly different from those of the first method described above, and for the schematic graphic as in the method described in Patent Document 1. A complicated calculation / correction process for generating a coordinate data string is unnecessary, and the data amount of the present embodiment is smaller than that of the second method described above for the following reason.

  The reason why the amount of data is smaller in the present embodiment than in the second method is as follows. In general, coordinate data for displaying a figure is expressed by about 8 to 32 bits in both the X and Y directions. For example, when the figure F shown in FIG. 6 is displayed on the assumption that the coordinate data is expressed in 8 bits in both the X and Y directions, the second conventional method uses coordinate data strings used for display at all levels. Since the number of coordinate points at level 0 is “5”, the number of coordinate points at level 1 is “4”, and the number of coordinate points at level 2 is “2” in FIG. The number is 176 (= {(5 + 4 + 2) * (8 * 2)}) bits.

  In contrast, in this embodiment, the coordinate data string other than the lowest level in the conventional method is replaced with a flag, so that the number of coordinate points of level 0 is “5”, the number of flags of level 1 is “5”, level Since the number of flags of 2 is “5”, the number of bits necessary for displaying the graphic F is 90 (= {5 * (8 * 2) + 5 + 5} bits. As described above, the amount of data can be reduced by using a flag instead of coordinate data of all levels as compared with the conventional second method.

110 Recording unit 120 Reading unit 130 Conversion unit 140 Input unit 150 Storage unit 160 Drawing unit 170 Display unit

Claims (4)

A first step of designating a display scale of a figure to be displayed from a plurality of predetermined display scales;
A coordinate data string in which the first coordinate data, which is coordinate data of a plurality of vertices required for drawing the detailed shape of the graphic of the first display scale having the maximum display scale, are arranged, and the display scale Is the coordinate data of one or more vertices required for drawing the approximate shape of the graphic at one or more second display scales, and is included in the first coordinate data One or more pieces of display graphic data having coordinate reference data for specifying the second coordinate data as coordinate data from the coordinate data string corresponding to each of the one or more second display scales are recorded. The display graphic data is read from the recording unit when any one of the second display scales is designated as the designated display scale by the first step, and the designated display scale in the display graphic data is read. Before A second step of identifying a configured group of coordinate data only in the second coordinate data corresponding to the specified display scale from the coordinate data string in said display figure data by coordinate reference data,
A third step of generating a rough coordinate data group obtained by correcting each coordinate value of the coordinate data group specified in the second step in the coordinate system of the designated display scale;
After storing the generated approximate coordinate data group in the storage unit, based on the approximate coordinate data group acquired from the storage unit, the approximate shape of the figure is drawn and displayed on the display unit at the designated display scale. A graphic display method comprising: a fourth step. An input means for designating a display scale of a graphic to be displayed from a plurality of predetermined display scales;
A coordinate data string in which the first coordinate data, which is coordinate data of a plurality of vertices required for drawing the detailed shape of the graphic of the first display scale having the maximum display scale, are arranged, and the display scale Is the coordinate data of one or more vertices required for drawing the approximate shape of the graphic at one or more second display scales, and is included in the first coordinate data One or more pieces of display graphic data having coordinate reference data for specifying the second coordinate data as coordinate data from the coordinate data string corresponding to each of the one or more second display scales are recorded. Recording means, and
When any one of the second display scales is designated as the designated display scale by the input means, the coordinate reference data corresponding to the designated display scale in the display graphic data read from the recording means, Each coordinate value of the coordinate data group composed only of the second coordinate data specified from the coordinate data string in the display graphic data according to the designated display scale is set in the coordinate system of the designated display scale. Conversion means for generating a corrected approximate coordinate data group;
Storage means for storing the approximate coordinate data group;
A graphic display device, comprising: a drawing unit that acquires the approximate coordinate data group from the storage unit and draws and displays the schematic shape of the graphic on the display unit at the designated display scale.   The coordinate reference data is a bit flag corresponding to the arrangement order of the first coordinate data from one or more first coordinate data constituting the coordinate data string for each second display scale. 3. The graphic display device according to claim 2, wherein the graphic display device comprises a flag string for specifying the second coordinate data.   The coordinate reference data is the designated display with a bit flag corresponding to the arrangement order of the coordinate data from the coordinate data of the first or second display scale having a one-stage display scale larger than the designated display scale. 3. The graphic display device according to claim 2, wherein a flag string for specifying the second coordinate data of a reduced scale is configured.