gmt-fork/doc/rst/source/explain_-J_full.rst_

.. _-J_full:

**-J**\ *parameters*

Select map projection. The first character of *parameters* determines the
projection. If the character is upper case then the argument(s) supplied
as scale(s) is interpreted to be the map width (or axis lengths), else
the scale argument(s) is the map scale (see its definition for each
projection). The *measurement unit* (called UNIT below) is cm, inch, or point, depending
on the :term:`PROJ_LENGTH_UNIT` setting in **gmt.conf**, but this can be
overridden on the command line by appending **c**, **i**, or **p** to
the *scale* or *width* values. Append **+dh**, **+du**, or **+dl** to the
given *width* if you instead want to set the map height, the maximum (upper)
dimension, or the minimum (lower) dimension, respectively [Default is **+dw** for width].
In case the central meridian is an optional parameter and it is being
omitted, then the center of the longitude range given by the **-R**
option is used. The default standard parallel is the equator.
The ellipsoid used in map projections is user-definable. 73 commonly used
ellipsoids and spheroids are currently supported, and users may also
specify their own custom ellipsoid parameters [Default is WGS-84].
Several GMT parameters can affect the projection: :term:`PROJ_ELLIPSOID`,
:term:`GMT_INTERPOLANT`, :term:`PROJ_SCALE_FACTOR`, and
:term:`PROJ_LENGTH_UNIT`; see the :doc:`gmt.conf` man page for details.
Choose one of the following projections and append the required parameters
(The **E** or **C** after projection names stands for Equal-Area and Conformal,
respectively):

    **CYLINDRICAL PROJECTIONS:**

.. _-Jc_full:

    **-Jc**\ *lon0/lat0/scale* or **-JC**\ *lon0/lat0/width* (Cassini).

        Give projection center *lon0/lat0* and *scale* (**1:**\ *xxxx* or UNIT/degree).

.. _-Jcyl_stere_full:

    **-Jcyl_stere**/[*lon0/*\ [*lat0/*]]\ *scale* or
    **-JCyl_stere**/[*lon0/*\ [*lat0/*]]\ *width* (Cylindrical Stereographic).

        Give central meridian *lon0* (optional), standard parallel *lat0*
        (optional), and *scale* along parallel (**1:**\ *xxxx* or
        UNIT/degree). The standard parallel is typically one of these (but
        can be any value):

          * 66.159467 - Miller's modified Gall
          * 55 - Kamenetskiy's First
          * 45 - Gall's Stereographic
          * 30 - Bolshoi Sovietskii Atlas Mira or Kamenetskiy's Second
          * 0 - Braun's Cylindrical

.. _-Jj_full:

    **-Jj**\ [*lon0/*]\ *scale* or **-JJ**\ [*lon0/*]\ *width* (Miller Cylindrical Projection).

        Give the central meridian *lon0* (optional) and *scale*
        (**1:**\ *xxxx* or UNIT/degree).

.. _-Jm_full:

    **-Jm**\ [*lon0/*\ [*lat0/*]]\ *scale* or **-JM**\ [*lon0/*\ [*lat0/*]]\ *width* (Mercator **[C]**)

        Give central meridian *lon0* (optional), standard parallel *lat0*
        (optional), and *scale* along parallel (**1:**\ *xxxx* or UNIT/degree).

.. _-Jo_full:

    **-Jo**\ *parameters*\ [**+v**] (Oblique Mercator **[C]**).

        Typically used with **-R**\ *LLx/LLy/URx/URy*\ **+r** or with projected coordinates.  Specify one of:

        **-Jo**\ [**a**\|\ **A**]\ *lon0/lat0/azimuth/scale* or **-JO**\ [**a**\|\ **A**]\ *lon0/lat0/azimuth/width*
            Set projection center *lon0/lat0*, *azimuth* of oblique equator, and *scale*.
        **-Jo**\ [**b**\|\ **B**]\ *lon0/lat0/lon1/lat1/scale* or **-JO**\ [**b**\|\ **B**]\ *lon0/lat0/lon1/lat1/width*
            Set projection center *lon0/lat0*, another point on the oblique
            equator *lon1/lat1*, and *scale*.
        **-Joc**\|\ **C**\ *lon0/lat0/lonp/latp/scale* or **-JOc**\|\ **C**\ *lon0/lat0/lonp/latp/width*
            Set projection center *lon0/lat0*, pole of oblique projection
            *lonp/latp*, and *scale*.
            Give *scale* along oblique equator (**1:**\ *xxxx* or UNIT/degree).

        Use upper-case **A**\|\ **B**\|\ **C** to remove enforcement of a northern hemisphere pole.
        Append **+v** to let the oblique Equator align with the *y*-axis [*x*-axis].

.. _-Jq_full:

    **-Jq**\ [*lon0/*\ [*lat0/*]]\ *scale* or
    **-JQ**\ [*lon0/*\ [*lat0/*]]\ *width* (Cylindrical Equidistant).

        Give the central meridian *lon0* (optional), standard parallel
        *lat0* (optional), and *scale* (**1:**\ *xxxx* or UNIT/degree). The
        standard parallel is typically one of these (but can be any value):

          * 61.7 - Grafarend and Niermann, minimum linear distortion
          * 50.5 - Ronald Miller Equirectangular
          * 43.5 - Ronald Miller, minimum continental distortion
          * 42 - Grafarend and Niermann
          * 37.5 - Ronald Miller, minimum overall distortion
          * 0 - Plate Carree, Simple Cylindrical, Plain/Plane Chart

.. _-Jt_full:

    **-Jt**\ *lon0/*\ [*lat0/*]\ *scale* or
    **-JT**\ *lon0/*\ [*lat0/*]\ *width* (Transverse Mercator **[C]**)

        Give the central meridian *lon0*, central parallel *lat0*
        (optional), and *scale* (**1:**\ *xxxx* or UNIT/degree).

.. _-Ju_full:

    **-Ju**\ *zone/scale* or **-JU**\ *zone/width* (UTM - Universal Transverse Mercator **[C]**).

        Give the UTM zone (A,B,1-60[C-X],Y,Z)) and *scale* (**1:**\ *xxxx* or UNIT/degree).
        Zones: If C-X not given, prepend - or + to enforce southern or
        northern hemisphere conventions [northern if south > 0].

.. _-Jy_full:

    **-Jy**\ [*lon0/*\ [*lat0/*]]\ *scale* or **-JY**\ [*lon0/*\ [*lat0/*]]\ *width* (Cylindrical Equal-Area **[E]**).

        Give the central meridian *lon0* (optional), standard parallel
        *lat0* (optional), and *scale* (**1:**\ *xxxx* or UNIT/degree). The
        standard parallel is typically one of these (but can be any value):

          * 50 - Balthasart
          * 45 - Gall
          * 37.0666 - Caster
          * 37.4 - Trystan Edwards
          * 37.5 - Hobo-Dyer
          * 30 - Behrman
          * 0 - Lambert (default)

    **CONIC PROJECTIONS:**

.. _-Jb_full:

    **-Jb**\ *lon0/lat0/lat1/lat2/scale* or **-JB**\ *lon0/lat0/lat1/lat2/width* (Albers **[E]**).
        Give projection center *lon0/lat0*, two standard parallels
        *lat1/lat2*, and *scale* (**1:**\ *xxxx* or UNIT/degree).

.. _-Jd_full:

    **-Jd**\ *lon0/lat0/lat1/lat2/scale* or **-JD**\ *lon0/lat0/lat1/lat2/width* (Conic Equidistant)
        Give projection center *lon0/lat0*, two standard parallels
        *lat1/lat2*, and *scale* (**1:**\ *xxxx* or UNIT/degree).

.. _-Jl_full:

    **-Jl**\ *lon0/lat0/lat1/lat2/scale* or **-JL**\ *lon0/lat0/lat1/lat2/width* (Lambert **[C]**)
        Give origin *lon0/lat0*, two standard parallels *lat1/lat2*, and
        *scale* along these (**1:**\ *xxxx* or UNIT/degree).

.. _-Jpoly_full:

    **-Jpoly**/[*lon0/*\ [*lat0/*]]\ *scale* or **-JPoly**/[*lon0/*\ [*lat0/*]]\ *width* ((American) Polyconic).
        Give the central meridian *lon0* (optional), reference parallel
        *lat0* (optional, default = equator), and *scale* along central
        meridian (**1:**\ *xxxx* or UNIT/degree).

    **AZIMUTHAL PROJECTIONS:**

    Except for polar aspects, **-R**\ w/e/s/n will be reset to **-Rg**.
    Use **-R**\ <...>\ **+r** for smaller regions.


.. _-Ja_full:

    **-Ja**\ *lon0/lat0*\ [*/horizon*]\ */scale* or **-JA**\ *lon0/lat0*\ [*/horizon*]\ */width* (Lambert **[E]**).
        *lon0/lat0* specifies the projection center. *horizon* specifies
        the max distance from projection center (in degrees, <= 180,
        default 90). Give *scale* as **1:**\ *xxxx* or *radius/lat*,
        where *radius* is distance in UNIT from origin to the oblique
        latitude *lat*.

.. _-Je_full:

    **-Je**\ *lon0/lat0*\ [*/horizon*]\ */scale* or **-JE**\ *lon0/lat0*\ [*/horizon*]\ */width* (Azimuthal Equidistant).
        *lon0/lat0* specifies the projection center. *horizon* specifies
        the max distance from projection center (in degrees, <= 180,
        default 180). Give *scale* as **1:**\ *xxxx* or *radius/lat*,
        where *radius* is distance in UNIT from origin to the oblique
        latitude *lat*.

.. _-Jf_full:

    **-Jf**\ *lon0/lat0*\ [*/horizon*]\ */scale* or **-JF**\ *lon0/lat0*\ [*/horizon*]\ */width* (Gnomonic).
        *lon0/lat0* specifies the projection center. *horizon* specifies
        the max distance from projection center (in degrees, < 90,
        default 60). Give *scale* as **1:**\ *xxxx* or *radius/lat*,
        where *radius* is distance in UNIT from origin to the oblique
        latitude *lat*.

.. _-Jg_full:

    **-Jg**\ *lon0/lat0*\ [*/horizon*]\ */scale* or **-JG**\ *lon0/lat0*\ [*/horizon*]\ */width* (Orthographic).
        *lon0/lat0* specifies the projection center. *horizon* specifies
        the max distance from projection center (in degrees, <= 90,
        default 90). Give *scale* as **1:**\ *xxxx* or *radius/lat*,
        where *radius* is distance in UNIT from origin to the oblique
        latitude *lat*.
    **-Jg**\ *lon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale* or **-JG**\ *lon0/lat0/altitude/azimuth/tilt/twist/Width/Height/width* (General Perspective).
        *lon0/lat0* specifies the projection center. *altitude* is the
        height (in km) of the viewpoint above local sea level. If
        *altitude* is less than 10, then it is the distance from the
        center of the earth to the viewpoint in earth radii. If
        *altitude* has a suffix **r** then it is the radius from the
        center of the earth in kilometers. *azimuth* is measured to the
        east of north of view. *tilt* is the upward tilt of the plane of
        projection. If *tilt* is negative, then the viewpoint is
        centered on the horizon. Further, specify the clockwise *twist*,
        *Width*, and *Height* of the viewpoint in degrees. Give *scale*
        as **1:**\ *xxxx* or *radius/lat*, where *radius* is distance in
        UNIT from origin to the oblique latitude *lat*.

.. _-Js_full:

    **-Js**\ *lon0/lat0*\ [*/horizon*]\ */scale* or **-JS**\ *lon0/lat0*\ [*/horizon*]\ */width* (General Stereographic **[C]**).
        *lon0/lat0* specifies the projection center. *horizon* specifies
        the max distance from projection center (in degrees, < 180,
        default 90). Give *scale* as **1:**\ *xxxx* (true at pole) or
        *lat0*/**1:**\ *xxxx* (true at standard parallel *lat*) or
        *radius/lat* (*radius* in UNIT from origin to the oblique
        latitude *lat*). Note if **1:**\ *xxxx* is used then to specify
        *horizon* you must also specify the *lat* as +-90 to avoid
        ambiguity.

    **MISCELLANEOUS PROJECTIONS:**

.. _-Jh_full:

    **-Jh**\ [*lon0/*]\ *scale* or **-JH**\ [*lon0/*]\ *width* (Hammer **[E]**).
        Give the central meridian *lon0* (optional) and *scale* along
        equator (**1:**\ *xxxx* or UNIT/degree).

.. _-Ji_full:

    **-Ji**\ [*lon0/*]\ *scale* or **-JI**\ [*lon0/*]\ *width* (Sinusoidal **[E]**).
        Give the central meridian *lon0* (optional) and *scale* along
        equator (**1:**\ *xxxx* or UNIT/degree).

.. _-Jk_full:

    **-Jkf**\ [*lon0/*]\ *scale* or **-JKf**\ [*lon0/*]\ *width* (Eckert IV) **[E]**).
        Give the central meridian *lon0* (optional) and *scale* along
        equator (**1:**\ *xxxx* or UNIT/degree).
    **-Jk**\ [**s**][*lon0/*]\ *scale* or **-JK**\ [**s**][*lon0/*]\ *width* (Eckert VI) **[E]**).
        Give the central meridian *lon0* (optional) and *scale* along
        equator (**1:**\ *xxxx* or UNIT/degree).

.. _-Jn_full:

    **-Jn**\ [*lon0/*]\ *scale* or **-JN**\ [*lon0/*]\ *width* (Robinson).
        Give the central meridian *lon0* (optional) and *scale* along
        equator (**1:**\ *xxxx* or UNIT/degree).

.. _-Jr_full:

    **-Jr**\ [*lon0/*]\ *scale* **-JR**\ [*lon0/*]\ *width* (Winkel Tripel).
        Give the central meridian *lon0* (optional) and *scale* along
        equator (**1:**\ *xxxx* or UNIT/degree).

.. _-Jv_full:

    **-Jv**\ [*lon0/*]\ *scale* or **-JV**\ [*lon0/*]\ *width* (Van der Grinten).
        Give the central meridian *lon0* (optional) and *scale* along
        equator (**1:**\ *xxxx* or UNIT/degree).

.. _-Jw_full:

    **-Jw**\ [*lon0/*]\ *scale* or **-JW**\ [*lon0/*]\ *width* (Mollweide **[E]**).
        Give the central meridian *lon0* (optional) and *scale* along
        equator (**1:**\ *xxxx* or UNIT/degree).

    **NON-GEOGRAPHICAL PROJECTIONS:**

.. _-Jp_full:

    **-Jp**\ *scale*\ [**+a**]\ [**+f**\ [**e**\|\ **p**\|\ *radius*]][**+r**\ *offset*][**+t**\ *origin*][**+z**\ [**p**\|\ *radius*]]] or **-JP**\ *width*\ [**+a**]\ [**+f**\ [**e**\|\ **p**\|\ *radius*]][**+r**\ *offset*][**+t**\ *origin*][**+z**\ [**p**\|\ *radius*]]
    (Polar coordinates (*theta*, *r*))

    Give *scale* in UNIT/r-unit.  Optionally add **+a** if *theta* is azimuth CW
    from North instead of direction CCW from East [Default].
    Append **+f** to flip the radial direction to point inwards, and append **e** to indicate
    that *r* represents *elevations* in degrees (requires *south* >= 0 and *north* <= 90),
    **p** to select current planetary radius (determined by :term:`PROJ_ELLIPSOID`) as maximum radius [*north*], or *radius*
    to specify a custom radius.
    Append **+r**\ *offset* to include a radial offset in measurement units [0].
    Append **+t**\ *origin* in degrees so that this angular value is aligned with the positive *x*-axis
    (or the azimuth to be aligned with the positive *y*-axis if **+a**) [0].
    Finally, append **+z** if you want to annotate depth rather than radius [Default].
    Alternatively, if your *r* data are actually depths then you can append **p** or *radius* to get
    radial annotations (*r = radius - z*) instead.

.. _-Jx_full:

    **-Jx**\ *x-scale*\ [*/y-scale*] or **-JX**\ *width*\ [*/height*] (Linear, log, and power scaling)

    Give *x-scale* (**1:**\ *xxxx* or UNIT/x-unit) and/or *y-scale*
    (**1:**\ *xxxx* or UNIT/y-unit); or specify *width* and/or *height*
    in UNIT. *y-scale*\ =\ *x-scale* if not specified separately and
    using **1:**\ *xxxx* implies that x-unit and y-unit are in meters.
    Use negative scale(s) to reverse the direction of an axis (e.g., to
    have y be positive down). Set *height* or *width* to 0 to have it
    recomputed based on the implied scale of the other axis. Optionally,
    append to *x-scale*, *y-scale*, *width* or *height* one of the
    following:

        **d**
           Data are geographical coordinates (in degrees).
        **l**
           Take log10 of values before scaling.
        **p**\ *power*
           Raise values to *power* before scaling.
        **t**
           Input coordinates are time relative to :term:`TIME_EPOCH`.
        **T**
           Input coordinates are absolute time.

	For mixed axes with only one geographic axis you may need to set **-f** as well.

When **-J** is used without any further arguments, or just with the
projection type, the arguments of the last used **-J**, or the last used
**-J** with that projection type, will be used.