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
|
<!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>6.5 A 3-D illuminated surface in black and white</TITLE>
<META NAME="description" CONTENT="6.5 A 3-D illuminated surface in black and white">
<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="node79.html">
<LINK REL="previous" HREF="node77.html">
<LINK REL="up" HREF="node73.html">
<LINK REL="next" HREF="node79.html">
</HEAD>
<BODY bgcolor="#ffffff">
<!--Navigation Panel-->
<A NAME="tex2html2122"
HREF="node79.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.gif"></A>
<A NAME="tex2html2116"
HREF="node73.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.gif"></A>
<A NAME="tex2html2110"
HREF="node77.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.gif"></A>
<A NAME="tex2html2118"
HREF="node1.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.gif"></A>
<A NAME="tex2html2120"
HREF="node149.html">
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.gif"></A>
<BR>
<B> Next:</B> <A NAME="tex2html2123"
HREF="node79.html">6.6 Plotting of histograms</A>
<B> Up:</B> <A NAME="tex2html2117"
HREF="node73.html">6. Cook-book</A>
<B> Previous:</B> <A NAME="tex2html2111"
HREF="node77.html">6.4 A 3-D perspective</A>
  <B> <A NAME="tex2html2119"
HREF="node1.html">Contents</A></B>
  <B> <A NAME="tex2html2121"
HREF="node149.html">Index</A></B>
<BR>
<BR>
<!--End of Navigation Panel-->
<H1><A NAME="SECTION001450000000000000000"></A>
<A NAME="10527"></A>
<BR>
6.5 A 3-D illuminated surface in black and white
</H1>
<P>
Instead of a mesh plot we may choose to show 3-D surfaces using
artificial illumination. For this example we will use
<A NAME="tex2html388"
HREF="../grdmath.html"><I><B>grdmath</B></I></A><A NAME="10537"></A> to make a grdfile that contains the surface given
by the function <!-- MATH
$z(x, y) = \cos (2\pi r/8)\cdot e^{-r/10}$
-->
<IMG
WIDTH="183" HEIGHT="37" ALIGN="MIDDLE" BORDER="0"
SRC="img102.gif"
ALT="$z(x, y) = \cos (2\pi r/8)\cdot e^{-r/10}$">, where
<!-- MATH
$r^2 = (x^2 + y^2)$
-->
<IMG
WIDTH="94" HEIGHT="35" ALIGN="MIDDLE" BORDER="0"
SRC="img103.gif"
ALT="$r^2 = (x^2 + y^2)$">. The illumination is obtained by passing
two grdfiles to <A NAME="tex2html389"
HREF="../grdview.html"><I><B>grdview</B></I></A><A NAME="10546"></A>: One with the <I>z</I>-values
(the surface) and another with intensity values (which should
be in the <IMG
WIDTH="16" HEIGHT="29" ALIGN="MIDDLE" BORDER="0"
SRC="img53.gif"
ALT="$\pm$">1 range). We use <A NAME="tex2html390"
HREF="../grdgradient.html"><I><B>grdgradient</B></I></A><A NAME="10555"></A> to compute
the horizontal gradients in the direction of the artificial
light source. The <U>gray.cpt</U> file only has one line that states
that all <I>z</I> values should have the gray level 128. Thus,
variations in shade are entirely due to variations in gradients,
or illuminations. We choose to illuminate from the SW and view
the surface from SE:
<P>
<P>
<BR>
<P>
<BR CLEAR="ALL">
<HR>
<BR>
<PRE>
grdmath -R-15/15/-15/15 -I0.3 X Y HYPOT DUP 2 MUL PI MUL 8 DIV COS EXCH NEG 10 DIV EXP MUL \
= sombrero.grd
echo '-5 128 5 128' >! gray.cpt
grdgradient sombrero.grd -A225 -Gintensity.grd -Nt0.75
grdview sombrero.grd -JX6i -JZ2i -B5/5/0.5SEwnZ -N-1/255/255/255 -Qs -Iintensity.grd -X1.5i -K \
-Cgray.cpt -R-15/15/-15/15/-1/1 -E120/30 -U/-1.25i/-0.75i/"Example 5 in Cookbook" >! example_05.ps
echo "4.1 5.5 50 0 33 2 z(r) = cos (2@~p@~r/8) * e@+-r/10@+" | pstext -R0/11/0/8.5 -Jx1i -O \
>> example_05.ps
\rm -f gray.cpt sombrero.grd intensity.grd .gmtcommands
</PRE>
<P>
<BR>
<BR>
<P>
<BR CLEAR="ALL">
<HR>
<P>
The variations in intensity could be made more dramatic by
using <A NAME="tex2html391"
HREF="../grdmath.html"><I><B>grdmath</B></I></A><A NAME="10617"></A> to scale the intensity file before
running <A NAME="tex2html392"
HREF="../grdview.html"><I><B>grdview</B></I></A><A NAME="10626"></A>. For very rough data sets one may
improve the smoothness of the intensities by passing the
output of <A NAME="tex2html393"
HREF="../grdgradient.html"><I><B>grdgradient</B></I></A><A NAME="10635"></A> to <A NAME="tex2html394"
HREF="../grdhisteq.html"><I><B>grdhisteq</B></I></A><A NAME="10644"></A>. The
shell-script above will result in a plot like the one in
Figure <A HREF="node78.html#fig:GMT_example_05">6.5</A>.
<P></P>
<DIV ALIGN="CENTER"><A NAME="fig:GMT_example_05"></A><A NAME="10653"></A>
<TABLE>
<CAPTION ALIGN="BOTTOM"><STRONG>Figure 6.5:</STRONG>
3-D illuminated surface</CAPTION>
<TR><TD><IMG
WIDTH="500" HEIGHT="358" BORDER="0"
SRC="img104.gif"
ALT="\begin{figure}\centering\epsfig{figure=eps/GMT_example_05.eps}\end{figure}"></TD></TR>
</TABLE>
</DIV><P></P>
<P>
<A NAME="10606"></A>
<P>
<HR>
<!--Navigation Panel-->
<A NAME="tex2html2122"
HREF="node79.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.gif"></A>
<A NAME="tex2html2116"
HREF="node73.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.gif"></A>
<A NAME="tex2html2110"
HREF="node77.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.gif"></A>
<A NAME="tex2html2118"
HREF="node1.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.gif"></A>
<A NAME="tex2html2120"
HREF="node149.html">
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.gif"></A>
<BR>
<B> Next:</B> <A NAME="tex2html2123"
HREF="node79.html">6.6 Plotting of histograms</A>
<B> Up:</B> <A NAME="tex2html2117"
HREF="node73.html">6. Cook-book</A>
<B> Previous:</B> <A NAME="tex2html2111"
HREF="node77.html">6.4 A 3-D perspective</A>
  <B> <A NAME="tex2html2119"
HREF="node1.html">Contents</A></B>
  <B> <A NAME="tex2html2121"
HREF="node149.html">Index</A></B>
<!--End of Navigation Panel-->
<ADDRESS>
Paul Wessel
2001-04-18
</ADDRESS>
</BODY>
</HTML>
|
