mapug.html

A mapping package for Matlab:这是一款功能十分强大的地理绘图工具包

in longitude/latitude, then <code>m_contour</code> or <code>m_contourf</code>
can be used to plot that data. </p>
<ol>
  <h3> <a name="p8.1"> <li> <br>
  </li>
  </a> <a href="http://topex.ucsd.edu/marine_topo/text/topo.html">Sandwell
and Smith Bathymetry </a> </h3>
  <p> A recent new bathymetry with approximately 1km resolution in
lower latitude areas is being used by many people. This dataset is
described
at <a href="http://topex.ucsd.edu/marine_topo">
http://topex.ucsd.edu/marine_topo/&nbsp; </a> and is available as a
134Mb binary file at <a
 href="ftp://topex.ucsd.edu/pub/global_topo_2min">
ftp://topex.ucsd.edu/pub/global_topo_2min/ </a> (get the file
topo_X.Y.img where X.Y is the version number). The authors have
included an m-file (<a
 href="ftp://topex.ucsd.edu/pub/global_topo_2min/matlab/mygrid_sand.m">mygrid_sand.m</a>)
which can extract portions of the data (you will have to modiy path
names within the code). Once this database (and the m-file) is
installed on
your computer, you can use it in M_Map very easily. A typical usage is
as follows: </p>
  <pre>% Extract data<br>[elevations,lat,lon]=mygrid_sand([lat_south lat_north long_west long_east]);<br><br>% Use in M_Map command<br>m_contour(lon,lat,elevations);<br></pre>
For some projections, you must make sure that the 'lon' values returned
by <code>mygrid_sand.m</code> fall within the range used in this
projection (i.e. you may have to add/subtract 360). This seems to
happen all the time for areas in the west (i.e. negative longitudes),
if you forget this you often end up with bewildering error messages
about empty vectors!
</ol>
<hr>
<h2><a name="10._Using_TerrainBase_5-minute_global"></a> <a name="p9">10.
Using TerrainBase 5-minute or ETOPO2 2-minute global
bathymetry/topography </a> </h2>
<ol>
<li> <p> For many purposes the elevation database accessed by M_Map
provides
adequate resolution. However, there are also many cases when more
detail
is desired. I have not included a higher-resolution database because it
would greatly increase the size of the package. However, v1.2 includes
m-files to access and plot a popular global 5-minute
bathymetry/topography database, after a few minutes of work. </p>
<p> This section provides instructions on how to download <a
 href="http://dss.ucar.edu/datasets/ds759.2/"> TerrainBase</a>, and
convert it from a 56Mb ASCII file to a 18Mb binary file using <code>
m_tba2b.m</code>. It is then straightforward to access and plot
bathymetry from this file using <code> m_tbase.m</code>, which is in
every way functionally identical to <code>m_elev</code> (see Section <a
 href="#p3.2">3.2</a>). </p>
<p> TerrainBase is also available on CDrom, and is also commonly
stored
in netcdf (or other) binary format somewhere on many academic networks.
If you modify <code> m_tbase.m </code> to access data from one of
these sources, let me know! </p>
<p> How to install TerrainBase: </p>
<ol>
  <li> get and uncompress the tbase.Z file from <a
 href="http://dss.ucar.edu/datasets/ds759.2/">http://dss.ucar.edu/datasets/ds759.2/
    </a> into the m_map directory.
    <p> </p>
  </li>
  <li> Run <code> m_tba2b('PATHNAME') </code> to store the
resulting
18Mb binary file as <code> PATHNAME/tbase.int</code>.
    <p> </p>
  </li>
  <li> Delete the original ASCII file <code>tbase</code>.
    <p> </p>
  </li>
  <li> Edit the <code>PATHNAME</code> setting in <code>m_tbase</code>
to point to the location of this file. </li>
</ol>
That's it! Test things out with this map of the western mediterranean:
<pre>m_proj('lambert','lon',[-10 20],'lat',[33 48]);<br>m_tbase('contourf');<br>m_grid('linestyle','none','tickdir','out','linewidth',3);<br></pre>
<center> <img src="./extbase.gif"> </center>
<br>
</li>
<li> As of Apr 2006, there is a corrected higher-resolution (2 minute) database <a
 href="http://dss.ucar.edu/datasets/ds759.3/"> ETOPO2</a>. Download 
 <a href="http://dss.ucar.edu/datasets/ds759.3/data/etopo2_2006apr/etopo2_2006apr.raw.gz"> 
 http://dss.ucar.edu/datasets/ds759.3/data/etopo2_2006apr/etopo2_2006apr.raw.gz</a> (a gzipped binary),
 gunzip it into a 116Mb file, edit the <code>PATHNAME</code> setting in <code>m_etopo2</code>
to point to the location of this file, and then use it in the same way as <code>m_tbase</code>
and <code>m_elev</code>. UCAR requires users to register and the second link won't work without you doing
this (go to first link and follow instructions). 
</li>
</ol> 

<h2> <a name="p9.5">11. Using GSHHS high-resolution coastline
database </a> </h2>
<p> </p>
<ol>
  <h3> <a name="p9.6"> <li> Installing GSHHS </li>
  </a></h3>
  <a name="p9.6"> </a>
  <p> When drawing maps there is always a tradeoff between the
execution
time of the generating program and the resolution of the resulting map.
Included in M_Map is a 1/4 degree coastline database which can be used
to generate very fast maps, with adequate resolution for many purposes.
  </p>
  <p> However, it is often desirable to be able to make detailed maps
of
limited geographic areas. For this purpose a higher-resolution
coastline
database is necessary. I have not included such a database in M_Map
because
it would greatly increase the size of the package. However, I have
included
m-files to access and use a popular high-resolution database called <a
 href="http://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html"> GSHHS </a>
  </p>
  <p> As distributed, GSHHS consists of a hierarchical set of
databases
at different resolutions. The lowest or "crude" resolution is not as
good
as the M_Map database, although it contains many more inland lakes. The
"high" resolution consists of points about 200m apart. There is also an
even
finer "full" resolution. You can install part or all of the database
(depending on how much disk space you have available). The "full"
resolution occupies 90Mb of disk space, and successively coarser
resolutions are smaller by about 1/4. Thus "high" resolution occupies
21Mb, "intermediate" uses 6Mb, and "low" uses 1.1Mb (one reason for not
always using "high" resolution
is that the entire 90Mb database must be read and processed each call,
which may take some time). </p>
  <p> How to install GSHHS: </p>
  <ol>
    <li> Go to <a
 href="http://www.ngdc.noaa.gov/mgg/shorelines/data/gshhs/">
http://www.ngdc.noaa.gov/mgg/shorelines/data/gshhs/</a>. </li>
    <li> Get and uncompress any or all of the files <code>
gshhs_c.b.gz, gshhs_l.b.gz, gshhs_i.b.gz</code> and/or <code>gshhs_h.b.gz</code>
in a convenient directory. One useful place is in <code>m_map/private</code>.
GSHHS data format has changed between v1.2 and 1.3, but m_map
should be able to figure this out.</li>
    <li> If the database files are not in subdirectory <code>
m_map/private </code>, you must edit the <code>FILNAME</code>
settings in <code>m_gshhs_c.m, m_gshhs_l.m, m_gshhs_i.m, m_gshhs_h.m</code>
and/or <code>m_gshhs_f.m</code> to point to the appropriate files. </li>
  </ol>
  <h3> <a name="p9.7"> <li> Using GSHHS effectively </li>
  </a></h3>
  <a name="p9.7"> </a> The simplest calling mechanism is identical
to
that for <code> m_coast </code> (<a href="#p3"> Section 3 </a>). For
example, to draw a gray-filled high-resolution coastline,
  <pre>m_gshhs_h('patch',[.5 .5 .5]);<br></pre>
is sufficient. However, execution times may be very, very long, as the
entire database must be searched and processed. I would not recommend
trying to draw world maps with the intermediate or high-resolution
coastlines! There are two ways to speed this up. The first is merely to
use a lower-resolution database, with fewer points. The second is
useful if you are going to
be repeatedly drawing a map (because, for example, it's the base figure
for your work). In this case I recommend that you save an intermediate
processed (generally smaller) file as follows:
  <pre>m_proj ...  % set up projection parameters<br><br>% This command does not draw anything - it merely processes the <br>% high-resolution database using the current projection parameters <br>% to generate a smaller coastline file called "gumby"<br><br>m_gshhs_h('save','gumby');<br><br>% Now we can draw a few maps of the same area much more quickly<br><br>figure(1);<br>m_usercoast('gumby','patch','r');<br>m_grid;<br><br>figure(2);<br>m_usercoast('gumby','linewidth',2,'color','b');<br>m_grid('tickdir','out','yaxisloc','left');<br><br>etc.<br></pre>
</ol>
<hr>
<h2> <a name="p10">12. M_Map toolbox contents and description </a> </h2>
<p> </p>
<ol>
  <li> Contents.m - toolbox contents </li>
  <li> m_demo.m - demonstrates a few maps. </li>
</ol>
User-callable functions
<ol>
  <li> m_proj.m - initializes projection</li>
  <li>m_coord - geomagnstic to geographic coords<br clear="all">
    <br>
  </li>
  <li>m_grid.m - draws grids </li>
  <li> m_scale.m - forces map to a given scale
    <p> </p>
  </li>
  <li> m_ungrid.m - erases map elements (if you want to change
parameters)
    <p> </p>
  </li>
  <li> m_coast.m - draws a coastline </li>
  <li> m_elev.m - draws elevation data </li>
  <li> m_tbase.m - draws elevation data from high-resolution database </li>
  <li> m_etopo2.m - draws elevation data from (another) high-resolution database </li>
  <li> m_gshhs_c.m - draws coastline from GSHHS crude database </li>
  <li> m_gshhs_l.m - draws coastline from GSHHS low-resolution
database </li>
  <li> m_gshhs_i.m - draws coastline from GSHHS
intermediate-resolution
database </li>
  <li> m_gshhs_h.m - draws coastline from GSHHS high-resolution
database </li>
  <li> m_gshhs_f.m - draws coastline from GSHHS full resolution
database </li>
  <li> m_plotbndry.m - draws a political boundary from the DCW </li>
  <li> m_usercoast.m - draws a coastline using a user-specified
subset database.
    <p> </p>
  </li>
  <li> m_plot.m - draws line data in map coords </li>
  <li> m_line.m - draws line data in map coords </li>
  <li> m_text.m - adds text data in map coords </li>
  <li> m_legend.m - Draw a legend box </li>
  <li> m_patch.m - adds patch data in map coords</li>
  <li>m_pcolor - draws pcolor surface<br>
  </li>
  <li> m_quiver - draws arrows for vector data </li>
  <li> m_contour - draws contour lines for gridded data </li>
  <li> m_contourf - draws filled contours </li>
  <li> m_track - draws annotated tracklines </li>
  <li> m_range_ring - draws range rings
    <p> </p>
  </li>
  <li> m_ll2xy.m - converts from long/lat to map coordinates </li>
  <li> m_xy2ll.m - converts from map coordinates to long/lat</li>
  <li>m_geo2mag - converts from magnetic to geographic coords</li>
  <li>m_mag2geo - the reverse<br clear="all">
    <br>
  </li>
  <li> m_lldist - distance between long/lat points </li>
  <li> m_xydist - distance between map coordinate points</li>
  <br>
  <li> m_fdist - location of point at given range/bearing along
ellipsoidal earth </li>
  <li> m_idist - range/bearings between points on ellipsoidal earth </li>
  <li> m_geodesic - points on geodesics between given points on
ellipsoidal earth <br>
  </li>
  <li> m_tba2b.m - used in installing high-resolution elevation
database.
    <p> </p>
  </li>
  <li> m_vec.m - fancy arrows </li>
</ol>
Internal functions (not meant to be user-callable)
<ol>
  <li> private/mp_azim.m - azimuthal projections </li>
  <li> private/mp_cyl.m - cylindrical projections (equatorial) </li>
  <li> private/mp_conic.m - conic projections </li>
  <li> private/mp_tmerc.m - transverse cylindrical projections </li>
  <li> private/mp_utm.m - elliptical universal transverse cylindrical
projections </li>
  <li> private/mp_omerc.m - oblique cylindrical projection
    <p> </p>
  </li>
  <li> private/mu_util.m - various utility routines </li>
  <li> private/mu_coast.m - routines to handle coastlines.</li>
  <li>private/mc_coords - coordinate conversion.<br>
  </li>
  <li> private/clabel.m - patched version of clabel (matlab v5.1
version