1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<!--Converted with LaTeX2HTML 99.2beta8 (1.46)
original version by: Nikos Drakos, CBLU, University of Leeds
* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan
* with significant contributions from:
Jens Lippmann, Marek Rouchal, Martin Wilck and others -->
<HTML>
<HEAD>
<TITLE>5.3.4 Azimuthal Equidistant Projection (-Je -JE)</TITLE>
<META NAME="description" CONTENT="5.3.4 Azimuthal Equidistant Projection (-Je -JE)">
<META NAME="keywords" CONTENT="GMT_Docs">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="Generator" CONTENT="LaTeX2HTML v99.2beta8">
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
<LINK REL="STYLESHEET" HREF="GMT_Docs.css">
<LINK REL="next" HREF="node55.html">
<LINK REL="previous" HREF="node53.html">
<LINK REL="up" HREF="node45.html">
<LINK REL="next" HREF="node55.html">
</HEAD>
<BODY bgcolor="#ffffff">
<!--Navigation Panel-->
<A NAME="tex2html1759"
HREF="node55.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.gif"></A>
<A NAME="tex2html1753"
HREF="node45.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.gif"></A>
<A NAME="tex2html1747"
HREF="node53.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.gif"></A>
<A NAME="tex2html1755"
HREF="node1.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.gif"></A>
<A NAME="tex2html1757"
HREF="node149.html">
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.gif"></A>
<BR>
<B> Next:</B> <A NAME="tex2html1760"
HREF="node55.html">5.3.5 Gnomonic Projection (-Jf</A>
<B> Up:</B> <A NAME="tex2html1754"
HREF="node45.html">5.3 Azimuthal Projections</A>
<B> Previous:</B> <A NAME="tex2html1748"
HREF="node53.html">5.3.3 Orthographic Projection (-Jg</A>
  <B> <A NAME="tex2html1756"
HREF="node1.html">Contents</A></B>
  <B> <A NAME="tex2html1758"
HREF="node149.html">Index</A></B>
<BR>
<BR>
<!--End of Navigation Panel-->
<H2><A NAME="SECTION001334000000000000000">
5.3.4 Azimuthal Equidistant Projection (<B>-Je </B> <B>-JE</B>)</A>
</H2>
<P>
<A NAME="7284"></A>
<A NAME="7297"></A>
<A NAME="7298"></A>
<P>
The most noticeable feature of this azimuthal projection is the
fact that distances measured from the center are true. Therefore,
a circle about the projection center defines the locus of points
that are equally far away from the plot origin. Furthermore,
directions from the center are also true. The projection, in
the polar aspect, is at least several centuries old. It is a
useful projection for a global view of locations at various or
identical distance from a given point (the map center).
<P>
To specify the azimuthal equidistant projection you must supply:
<P>
<DL>
<DT><STRONG><IMG
WIDTH="12" HEIGHT="13" ALIGN="BOTTOM" BORDER="0"
SRC="img54.gif"
ALT="$\bullet$"></STRONG></DT>
<DD>Longitude and latitude of the projection center.
<P>
</DD>
<DT><STRONG><IMG
WIDTH="12" HEIGHT="13" ALIGN="BOTTOM" BORDER="0"
SRC="img54.gif"
ALT="$\bullet$"></STRONG></DT>
<DD>Scale as 1:xxxxx or as radius/latitude where
radius is distance on map in inches from projection center to
a particular [possibly oblique] latitude (<B>-Je</B>), or map
width (<B>-JE</B>).
</DD>
</DL>
<P>
Our example of a global view centered on 100<IMG
WIDTH="11" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
SRC="img61.gif"
ALT="$^{o}$">W/40<IMG
WIDTH="11" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
SRC="img61.gif"
ALT="$^{o}$">N
can therefore be generated by the following <A NAME="tex2html321"
HREF="../pscoast.html"><I><B>pscoast</B></I></A><A NAME="7320"></A>
command. Note that the antipodal point is 180<IMG
WIDTH="11" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
SRC="img61.gif"
ALT="$^{o}$"> away from
the center, but in this projection this point plots as the
entire map perimeter:
<P>
<P>
<BR>
<P>
<BR CLEAR="ALL">
<HR>
<BR>
<PRE>
#!/bin/sh
# $Id: GMT_az_equidistant.sh,v 1.1 2001/03/21 04:10:21 pwessel Exp $
#
pscoast -R0/360/-90/90 -JE-100/40/4.5i -B15g15 -Dc -A10000 -G200 -W0.25p -P > GMT_az_equidistant.ps
</PRE>
<P>
<BR>
<BR>
<P>
<BR CLEAR="ALL">
<HR>
<P>
<P></P>
<DIV ALIGN="CENTER"><A NAME="fig:GMT_az_equidistant"></A><A NAME="7432"></A>
<TABLE>
<CAPTION ALIGN="BOTTOM"><STRONG>Figure 5.16:</STRONG>
World map using the equidistant azimuthal projection.</CAPTION>
<TR><TD><IMG
WIDTH="520" HEIGHT="520" BORDER="0"
SRC="img78.gif"
ALT="\begin{figure}\centering\epsfig{figure=eps/GMT_az_equidistant.eps}\end{figure}"></TD></TR>
</TABLE>
</DIV><P></P>
<P>
<A NAME="7408"></A>
<A NAME="7425"></A>
<A NAME="7426"></A>
<P>
<HR>
<!--Navigation Panel-->
<A NAME="tex2html1759"
HREF="node55.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.gif"></A>
<A NAME="tex2html1753"
HREF="node45.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.gif"></A>
<A NAME="tex2html1747"
HREF="node53.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.gif"></A>
<A NAME="tex2html1755"
HREF="node1.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.gif"></A>
<A NAME="tex2html1757"
HREF="node149.html">
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.gif"></A>
<BR>
<B> Next:</B> <A NAME="tex2html1760"
HREF="node55.html">5.3.5 Gnomonic Projection (-Jf</A>
<B> Up:</B> <A NAME="tex2html1754"
HREF="node45.html">5.3 Azimuthal Projections</A>
<B> Previous:</B> <A NAME="tex2html1748"
HREF="node53.html">5.3.3 Orthographic Projection (-Jg</A>
  <B> <A NAME="tex2html1756"
HREF="node1.html">Contents</A></B>
  <B> <A NAME="tex2html1758"
HREF="node149.html">Index</A></B>
<!--End of Navigation Panel-->
<ADDRESS>
Paul Wessel
2001-04-18
</ADDRESS>
</BODY>
</HTML>
|
