CN102254480A - Method for correctly displaying coordinates of map with due north direction offsetting from directly-overhead direction in geographic information system (GIS) - Google Patents

Abstract

The invention discloses a method for correctly displaying coordinates of a map with a due north direction offsetting from a directly-overhead direction in a geographic information system (GIS), which is characterized by comprising the following steps of: taking the origin of the coordinates as a rotation center point by using the actual coordinate value of the map, registering the map by rotating the map to a coordinate value by the numerical value of an included angle between the due north direction of the map and the directly-overhead direction of the map, and after a map engineering file is opened in the GIS, reading the numerical value of the included angle between the due north direction of the map and the directly-overhead direction of the map, which corresponds to the map engineering file; and calculating by using a coordinate system rotation formula to convert the coordinates in the due north direction of the map, which is not the directly-overhead direction into the coordinates in the due north direction of the map, which is the directly-overhead direction, wherein in the converting process, the origin of the coordinates of the map before conversion is taken as the rotation center point. The coordinates in the due north direction of the map, which is not the directly-overhead direction, can be correctly displayed by the method, points are generated and the positions of the points are modified according to actual coordinate values, and the method is suitable to solve the problem that the due north direction of the map is not the directly-overhead direction in the development of various GISs and GSI-based secondary development.

Description

The method of the correct displaing coordinate in GIS of the map directly over a kind of direct north departs from

Technical field

The present invention relates to application of GIS, more specifically say so a kind of be used for realizing the positive north orientation of GIS map depart from directly over during the position, correctly show the method for its coordinate.

Background technology

Directly over generally all adopting, common map is direct north, i.e. " up north and down south left west and right east ".But, because the restriction of regional extent, reasons such as the needs of map printing and staff's use habit, some mappings be directly over non-direct north, be individual angle to be arranged between directly over positive north orientation of map and the map, as certain coal mine excavation scope is the elongate area of northwest to southeastern direction, the positive north orientation of map is plotted as directly over the map to taking back 20.456 °, so that four frames of map are level is vertical, label character in the map is parallel with the frame horizontal direction, thereby make things convenient for printing, the output of map, and the use of map.But, projection plane coordinates system commonly used is direct north directly over being in the GIS software, therefore, above-mentioned map is directly to read its actual coordinate figure in GIS software, also can't directly generate point in the GIS map according to the actual coordinate value, above-mentioned map uses comparatively inconvenience in actual GIS engineering project.

Summary of the invention

The present invention is for avoiding above-mentioned existing in prior technology problem, the method of the map of a kind of direct north directly over departing from correct displaing coordinate in GIS is proposed, so that directly over depart from the map of direct north actual coordinate can access correct demonstration, and according to an actual coordinate value generation point and a modification point position, thereby make things convenient for engineering to use.

Technical solution problem of the present invention adopts following technical scheme:

The method of the correct displaing coordinate in GIS of the map directly over direct north of the present invention departs from is characterized in that carrying out as follows:

1, in GIS to map to display registration in advance; The actual coordinate value is a rotary middle point with true origin O (0,0) according to the map, and rotation map direct north coordinate figure behind the angle numerical value directly over the map carries out registration, and the rotation computing formula adopts following formula:

$\left\{\begin{array}{c}x=x^{\′}\×\cos \mathrm{\α}+y^{\′}\×\sin \mathrm{\α}\\ y=y^{\′}\×\sin \mathrm{\α}+x^{\′}\×\cos \mathrm{\α}\end{array}\right.$

In the formula: (x y) is the coordinate of conversion back point, and (x ', y ') is the coordinate of point before the conversion, and the angle between α is the map direct north directly over the map is negative clockwise, is positive number counterclockwise;

2, when opening above-mentioned map with the newly-built map of GIS or the first time, to the angle between the positive north orientation, if the positive north orientation of map is directly over the map, then using default setting is 0 ° directly over the input map; Carry out despining by the coordinate system rotation formula then and calculate, in GIS, directly show correct coordinate;

When 3, GIS preserves map, preserve described angle parameter simultaneously, described angle parameter preserving type can for: be stored in the computing machine or be stored in the GIS map project file or be kept in the registration table with the individual files form;

4, GIS is for the second time and when opening this map afterwards, automatically the map correspondence of being preserved in the read step (3) directly over to the angle between the positive north orientation; Utilize the coordinate system rotation formula to carry out despining again and calculate, realize the positive north orientation of map non-directly under the situation coordinate with north orientation just be directly over the conversion between the coordinate under the situation, thereby show correct coordinate; During conversion, be the central point of rotation with the map reference initial point O before changing equally.

Compared with the prior art, beneficial effect of the present invention is embodied in:

1, the inventive method can make the actual coordinate of the map of direct north directly over departing from be shown correctly that in GIS its principle is simple, and slewing rate is fast and accurately, thereby greatly makes things convenient for engineering to use.

2, the inventive method also can be used for the map of direct north directly over departing from, and generates the point of tram in GIS according to the actual coordinate value, and revises some position etc. according to the actual coordinate value.

3, the described angle preserving type among the present invention is various, can be stored in the computing machine or is stored in the GIS map project file or is kept in the registration table with the individual files form.

Description of drawings

Fig. 1 is map the coordinate system synoptic diagram in common GIS software of positive north orientation directly over non-.

Fig. 2 is the map coordinates system postrotational synoptic diagram of positive north orientation directly over non-.

Embodiment

The method of the correct displaing coordinate in GIS of the map directly over direct north departs from the present embodiment is to carry out as follows:

1, in GIS to map to display registration in advance.The actual coordinate value is a rotary middle point with true origin O (0,0) according to the map, and rotation map direct north coordinate figure behind the angle numerical value directly over the map carries out registration.The rotation computing formula adopts following formula:

$\left\{\begin{array}{c}x=x^{\′}\×\cos \mathrm{\α}+y^{\′}\×\sin \mathrm{\α}\\ y=y^{\′}\×\sin \mathrm{\α}+x^{\′}\×\cos \mathrm{\α}\end{array}\right.$

In the formula: (x y) is the coordinate of conversion back point, and (x ', y ') is the coordinate of point before the conversion, and the angle between α is the map direct north directly over the map is negative clockwise, is positive number counterclockwise.

2, when with the newly-built map of GIS or when for the first time opening above-mentioned map, need this map of input directly over to the angle between the positive north orientation (if the positive north orientation of map is directly over the map, then use default setting, promptly 0 °, can import).Carry out despining by the coordinate system rotation formula then and calculate, in GIS, directly show correct coordinate.

When 3, GIS preserves map, preserve described angle parameter simultaneously, described angle parameter preserving type can for: be stored in the computing machine or be stored in the GIS map project file or be kept in the registration table with the individual files form.

4, GIS is for the second time and when opening this map afterwards, read automatically the map correspondence of being preserved in (3) directly over to the angle between the positive north orientation; Utilize the coordinate system rotation formula to carry out despining again and calculate, realize the positive north orientation of map non-directly under the situation coordinate with north orientation just be directly over the conversion between the coordinate under the situation, thereby show correct coordinate; During conversion, be the central point of rotation with the map reference initial point O before changing equally.

Embodiment: utilize the inventive method a generalized information system.

The employed map of system is certain mine, and its digging scope is the elongate area of northwest to southeastern direction, prints for convenience and publishes picture and use habit, and the drawing personnel are plotted as directly over the map the positive north orientation of map to taking back 20.456 °.This generalized information system is before using the inventive method, and its coordinate can not correctly show.Utilize the present invention successfully to solve this coordinate problem as follows.Concrete grammar is as follows:

1, to map registration in advance.The actual coordinate value is a rotary middle point with true origin O (0,0) according to the map, and rotation map direct north coordinate figure behind the angle numerical value directly over the map carries out registration.Since the positive north orientation of this map be directly over the map to taking back 20.456 °, so map direct north angle number (clockwise direction) directly over the map is-20.456.

The rotation computing formula adopts following formula:

$\left\{\begin{array}{c}x=x^{\′}\×\cos \mathrm{\α}+y^{\′}\×\sin \mathrm{\α}\\ y=y^{\′}\×\sin \mathrm{\α}+x^{\′}\×\cos \mathrm{\α}\end{array}\right.$

In the formula: (x y) is the coordinate of conversion back point, and (x ', y ') is the coordinate of point before the conversion, and the angle between α is the map direct north directly over the map is negative clockwise, is positive number counterclockwise.

The registration of present embodiment adopts four coordinates right, and its actual coordinate figure is respectively (480500,3634500), (490500,3631000), (488500,3627500), (479500,3631500), with these four coordinates to respectively as (x ', y '), α is-20.456, bring above-mentioned formula into and calculate, result of calculation is respectively (820013.9306,3573240.4976), (809421.3142,3573456.0843), (810071.9880,3569477.8153), (819902.4076,3570080.1871).With four coordinates after calculating to former figure is carried out registration.

2, when utilizing this generalized information system to open above-mentioned map for the first time, need this map of input directly over to the angle 20.456 between the positive north orientation (°).Then the map that this generalized information system is read arbitrarily the coordinate put before as conversion of some coordinate figures (x ', y '), α is+20.456, carries out despining by the coordinate system rotation formula and calculates, thereby obtain the actual coordinate value, and the coordinate figure after will calculating shows directly in this generalized information system.As first point (820013.9306,3573240.4976) despining is calculated actual coordinate value (480500,3634500).

When 3, generalized information system is preserved map, preserve the angle parameter simultaneously, the angle parameter is stored in the computing machine with individual files form (* .ini).* .ini file storage path is identical with the map file path, and title is defined as: " " adds name map, adds " ", and it thes contents are as follows:

[coordinate display parameter]

RotateAngle＝20.456

4, generalized information system is for the second time and when opening this map afterwards, automatically the value of RotateAngle correspondence in the * .ini file of being preserved in the read step 3; Utilize the coordinate system rotation formula to carry out despining again and calculate, realize the positive north orientation of map non-directly under the situation coordinate with north orientation just be directly over the conversion between the coordinate under the situation, thereby show correct coordinate; During conversion, be the central point of rotation with the map reference initial point O before changing equally.

The precision of the inventive method depends on the decimal digits of reservation, does not have other errors; Slewing rate is very fast, and directly reads mouse position and compares, and does not have delay substantially.

Claims (1)

1. the method for the correct displaing coordinate in GIS of the map directly over a direct north departs from is characterized in that carrying out as follows:

(1), in GIS to map to display registration in advance; The actual coordinate value is a rotary middle point with true origin O (0,0) according to the map, and rotation map direct north coordinate figure behind the angle numerical value directly over the map carries out registration, and the rotation computing formula adopts following formula:

$\left\{\begin{array}{c}x=x^{\′}\×\cos \mathrm{\α}+y^{\′}\×\sin \mathrm{\α}\\ y=y^{\′}\×\sin \mathrm{\α}+x^{\′}\×\cos \mathrm{\α}\end{array}\right.$

In the formula: (x y) is the coordinate of conversion back point, and (x ', y ') is the coordinate of point before the conversion, and the angle between α is the map direct north directly over the map is negative clockwise, is positive number counterclockwise;

(2), when with the newly-built map of GIS or when for the first time opening above-mentioned map, to the angle between the positive north orientation, if the positive north orientation of map is directly over the map, then using default setting is 0 ° directly over the input map; Carry out despining by the coordinate system rotation formula then and calculate, in GIS, directly show correct coordinate;

(3), when GIS preserves map, preserve described angle parameter simultaneously, described angle parameter preserving type can for: be stored in the computing machine or be stored in the GIS map project file or be kept in the registration table with the individual files form;

(4), GIS is for the second time and when opening this map afterwards, automatically the map correspondence of being preserved in the read step (3) directly over to the angle between the positive north orientation; Utilize the coordinate system rotation formula to carry out despining again and calculate, realize the positive north orientation of map non-directly under the situation coordinate with north orientation just be directly over the conversion between the coordinate under the situation, thereby show correct coordinate; During conversion, be the central point of rotation with the map reference initial point O before changing equally.

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