カスタム空間参照システム
Custom Coordinate Reference System
If QGIS does not provide the coordinate reference system you need, you can define a custom CRS. To define a CRS, select mIconNewCustom CRS from the Edit (Gnome, OSX) or Settings (KDE, Windows) menu. Custom CRS are stored in your QGIS user database. In addition to your custom CRS, this database also contains your spatial bookmarks and other custom data. <P>
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[clip=true, width=12cm]customProjectionDialog
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<P> Defining a custom CRS in QGIS requires a good understanding of the Proj.4 projection library. To begin, refer to the Cartographic Projection Procedures for the UNIX Environment - A User's Manual by Gerald I. Evenden, U.S. Geological Survey Open-File Report 90-284, 1990 (available at ftp://ftp.remotesensing.org/proj/OF90-284.pdf). This manual describes the use of the proj.4 and related command line utilities. The cartographic parameters used with proj.4 are described in the user manual, and are the same as those used by QGIS.
<P> The Custom Coordinate Reference System Definition dialog requires only two parameters to define a user CRS:
- a descriptive name and
- the cartographic parameters in PROJ.4 format.
To create a new CRS, click the mIconNewNew button and enter a descriptive name and the CRS parameters. After that you can save your CRS by clicking the button mActionFileSaveSave.
<P> Note that the Parameters must begin with a +proj=-block, to represent the new coordinate reference system.
<P> You can test your CRS parameters to see if they give sane results by clicking on the Calculate button inside the Test block and pasting your CRS parameters into the Parameters field. Then enter known WGS 84 latitude and longitude values in North and East fields respectively. Click on Calculate and compare the results with the known values in
your coordinate reference system.
