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<section id="unit-conversion">
<span id="unitconvert"></span><h1>Unit conversion<a class="headerlink" href="#unit-conversion" title="Permalink to this headline">¶</a></h1>
<div class="versionadded">
<p><span class="versionmodified added">New in version 5.0.0.</span></p>
</div>
<p>Convert between various distance, angular and time units.</p>
<table class="docutils align-default">
<colgroup>
<col style="width: 27%" />
<col style="width: 73%" />
</colgroup>
<tbody>
<tr class="row-odd"><td><p><strong>Alias</strong></p></td>
<td><p>unitconvert</p></td>
</tr>
<tr class="row-even"><td><p><strong>Domain</strong></p></td>
<td><p>2D, 3D or 4D</p></td>
</tr>
<tr class="row-odd"><td><p><strong>Input type</strong></p></td>
<td><p>Any</p></td>
</tr>
<tr class="row-even"><td><p><strong>Output type</strong></p></td>
<td><p>Any</p></td>
</tr>
</tbody>
</table>
<p>There are many examples of coordinate reference systems that are expressed in
other units than the meter. There are also many cases where temporal data
has to be translated to different units. The <cite>unitconvert</cite> operation takes care
of that.</p>
<p>Many North American systems are defined with coordinates in feet. For example
in Vermont:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>+proj=pipeline
+step +proj=tmerc +lat_0=42.5 +lon_0=-72.5 +k_0=0.999964286 +x_0=500000.00001016 +y_0=0
+step +proj=unitconvert +xy_in=m +xy_out=us-ft
</pre></div>
</div>
<p>Often when working with GNSS data the timestamps are presented in GPS-weeks,
but when the data transformed with the <cite>helmert</cite> operation timestamps are
expected to be in units of decimalyears. This can be fixed with <cite>unitconvert</cite>:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>+proj=pipeline
+step +proj=unitconvert +t_in=gps_week +t_out=decimalyear
+step +proj=helmert +epoch=2000.0 +t_obs=2017.5 ...
</pre></div>
</div>
<section id="parameters">
<h2>Parameters<a class="headerlink" href="#parameters" title="Permalink to this headline">¶</a></h2>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-arg-xy_in">
<span id="cmdoption-arg-xy-in"></span><span class="sig-name descname"><span class="pre">+xy_in</span></span><span class="sig-prename descclassname"><span class="pre">=<unit></span> <span class="pre">or</span> <span class="pre"><conversion_factor></span></span><a class="headerlink" href="#cmdoption-arg-xy_in" title="Permalink to this definition">¶</a></dt>
<dd><p>Horizontal input units. See <a class="reference internal" href="#distance-units"><span class="std std-ref">Distance units</span></a> and <a class="reference internal" href="#angular-units"><span class="std std-ref">Angular units</span></a>
for a list of available units. <cite><conversion_factor></cite> is the conversion factor
from the input unit to metre for linear units, or to radian for angular
units.</p>
</dd></dl>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-arg-xy_out">
<span id="cmdoption-arg-xy-out"></span><span class="sig-name descname"><span class="pre">+xy_out</span></span><span class="sig-prename descclassname"><span class="pre">=<unit></span> <span class="pre">or</span> <span class="pre"><conversion_factor></span></span><a class="headerlink" href="#cmdoption-arg-xy_out" title="Permalink to this definition">¶</a></dt>
<dd><p>Horizontal output units. See <a class="reference internal" href="#distance-units"><span class="std std-ref">Distance units</span></a> and <a class="reference internal" href="#angular-units"><span class="std std-ref">Angular units</span></a>
for a list of available units. <cite><conversion_factor></cite> is the conversion factor
from the output unit to metre for linear units, or to radian for angular
units.</p>
</dd></dl>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-arg-z_in">
<span id="cmdoption-arg-z-in"></span><span class="sig-name descname"><span class="pre">+z_in</span></span><span class="sig-prename descclassname"><span class="pre">=<unit></span> <span class="pre">or</span> <span class="pre"><conversion_factor></span></span><a class="headerlink" href="#cmdoption-arg-z_in" title="Permalink to this definition">¶</a></dt>
<dd><p>Vertical output units. See <a class="reference internal" href="#distance-units"><span class="std std-ref">Distance units</span></a> and <a class="reference internal" href="#angular-units"><span class="std std-ref">Angular units</span></a>
for a list of available units. <cite><conversion_factor></cite> is the conversion factor
from the input unit to metre for linear units, or to radian for angular
units.</p>
</dd></dl>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-arg-z_out">
<span id="cmdoption-arg-z-out"></span><span class="sig-name descname"><span class="pre">+z_out</span></span><span class="sig-prename descclassname"><span class="pre">=<unit></span> <span class="pre">or</span> <span class="pre"><conversion_factor></span></span><a class="headerlink" href="#cmdoption-arg-z_out" title="Permalink to this definition">¶</a></dt>
<dd><p>Vertical output units. See <a class="reference internal" href="#distance-units"><span class="std std-ref">Distance units</span></a> and <a class="reference internal" href="#angular-units"><span class="std std-ref">Angular units</span></a>
for a list of available units. <cite><conversion_factor></cite> is the conversion factor
from the output unit to metre for linear units, or to radian for angular
units.</p>
</dd></dl>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-arg-t_in">
<span id="cmdoption-arg-t-in"></span><span class="sig-name descname"><span class="pre">+t_in</span></span><span class="sig-prename descclassname"><span class="pre">=<unit></span></span><a class="headerlink" href="#cmdoption-arg-t_in" title="Permalink to this definition">¶</a></dt>
<dd><p>Temporal input units. See <a class="reference internal" href="#time-units"><span class="std std-ref">Time units</span></a> for a list of available units.</p>
</dd></dl>
<dl class="std option">
<dt class="sig sig-object std" id="cmdoption-arg-t_out">
<span id="cmdoption-arg-t-out"></span><span class="sig-name descname"><span class="pre">+t_out</span></span><span class="sig-prename descclassname"><span class="pre">=<unit></span></span><a class="headerlink" href="#cmdoption-arg-t_out" title="Permalink to this definition">¶</a></dt>
<dd><p>Temporal output units. See <a class="reference internal" href="#time-units"><span class="std std-ref">Time units</span></a> for a list of available units.</p>
</dd></dl>
</section>
<section id="distance-units">
<span id="id1"></span><h2>Distance units<a class="headerlink" href="#distance-units" title="Permalink to this headline">¶</a></h2>
<p>In the table below all distance units supported by PROJ are listed.
The same list can also be produced on the command line with <strong class="program">proj</strong> or
<strong class="program">cs2cs</strong>, by adding the <cite>-lu</cite> flag when calling the utility.</p>
<table class="docutils align-default">
<colgroup>
<col style="width: 23%" />
<col style="width: 77%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>Label</p></th>
<th class="head"><p>Name</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p>km</p></td>
<td><p>Kilometer</p></td>
</tr>
<tr class="row-odd"><td><p>m</p></td>
<td><p>Meter</p></td>
</tr>
<tr class="row-even"><td><p>dm</p></td>
<td><p>Decimeter</p></td>
</tr>
<tr class="row-odd"><td><p>cm</p></td>
<td><p>Centimeter</p></td>
</tr>
<tr class="row-even"><td><p>mm</p></td>
<td><p>Millimeter</p></td>
</tr>
<tr class="row-odd"><td><p>kmi</p></td>
<td><p>International Nautical Mile</p></td>
</tr>
<tr class="row-even"><td><p>in</p></td>
<td><p>International Inch</p></td>
</tr>
<tr class="row-odd"><td><p>ft</p></td>
<td><p>International Foot</p></td>
</tr>
<tr class="row-even"><td><p>yd</p></td>
<td><p>International Yard</p></td>
</tr>
<tr class="row-odd"><td><p>mi</p></td>
<td><p>International Statute Mile</p></td>
</tr>
<tr class="row-even"><td><p>fath</p></td>
<td><p>International Fathom</p></td>
</tr>
<tr class="row-odd"><td><p>ch</p></td>
<td><p>International Chain</p></td>
</tr>
<tr class="row-even"><td><p>link</p></td>
<td><p>International Link</p></td>
</tr>
<tr class="row-odd"><td><p>us-in</p></td>
<td><p>U.S. Surveyor’s Inch</p></td>
</tr>
<tr class="row-even"><td><p>us-ft</p></td>
<td><p>U.S. Surveyor’s Foot</p></td>
</tr>
<tr class="row-odd"><td><p>us-yd</p></td>
<td><p>U.S. Surveyor’s Yard</p></td>
</tr>
<tr class="row-even"><td><p>us-ch</p></td>
<td><p>U.S. Surveyor’s Chain</p></td>
</tr>
<tr class="row-odd"><td><p>us-mi</p></td>
<td><p>U.S. Surveyor’s Statute Mile</p></td>
</tr>
<tr class="row-even"><td><p>ind-yd</p></td>
<td><p>Indian Yard</p></td>
</tr>
<tr class="row-odd"><td><p>ind-ft</p></td>
<td><p>Indian Foot</p></td>
</tr>
<tr class="row-even"><td><p>ind-ch</p></td>
<td><p>Indian Chain</p></td>
</tr>
</tbody>
</table>
</section>
<section id="angular-units">
<span id="id2"></span><h2>Angular units<a class="headerlink" href="#angular-units" title="Permalink to this headline">¶</a></h2>
<div class="versionadded">
<p><span class="versionmodified added">New in version 5.2.0.</span></p>
</div>
<p>In the table below all angular units supported by PROJ <cite>unitconvert</cite> are listed.</p>
<table class="docutils align-default">
<colgroup>
<col style="width: 23%" />
<col style="width: 77%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>Label</p></th>
<th class="head"><p>Name</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p>deg</p></td>
<td><p>Degree</p></td>
</tr>
<tr class="row-odd"><td><p>grad</p></td>
<td><p>Grad</p></td>
</tr>
<tr class="row-even"><td><p>rad</p></td>
<td><p>Radian</p></td>
</tr>
</tbody>
</table>
</section>
<section id="time-units">
<span id="id3"></span><h2>Time units<a class="headerlink" href="#time-units" title="Permalink to this headline">¶</a></h2>
<p>In the table below all time units supported by PROJ are listed.</p>
<blockquote>
<div><div class="admonition note">
<p class="admonition-title">Note</p>
<p>When converting time units from a date-only format (<cite>yyyymmdd</cite>), PROJ
assumes a time value of 00:00 midnight. When converting time units
to a date-only format, PROJ rounds to the <em>nearest</em> date at 00:00
midnight. That is, any time values less than 12:00 noon will round to
00:00 on the same day. Time values greater than or equal to 12:00 noon
will round to 00:00 on the following day.</p>
</div>
</div></blockquote>
<table class="docutils align-default">
<colgroup>
<col style="width: 33%" />
<col style="width: 67%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>Label</p></th>
<th class="head"><p>Name</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p>mjd</p></td>
<td><p>Modified Julian date</p></td>
</tr>
<tr class="row-odd"><td><p>decimalyear</p></td>
<td><p>Decimal year</p></td>
</tr>
<tr class="row-even"><td><p>gps_week</p></td>
<td><p>GPS Week</p></td>
</tr>
<tr class="row-odd"><td><p>yyyymmdd</p></td>
<td><p>Date in yyyymmdd format</p></td>
</tr>
</tbody>
</table>
</section>
</section>
</div>
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