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
|
<!DOCTYPE doctype PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<meta name="generator" content=
"HTML Tidy for Mac OS X (vers 31 October 2006 - Apple Inc. build 16.1), see www.w3.org">
<meta http-equiv="Content-Type" content=
"text/html; charset=us-ascii">
<meta name="GENERATOR" content=
"Mozilla/4.78 [en] (X11; U; Linux 2.4.7-10 i686) [Netscape]">
<title>Contours</title>
</head>
<body vlink="#551A8B" text="#000000" link="#0000EE" bgcolor=
"#FFFFFF" alink="#FF0000">
<h3><img alt="" src="../sun.gif" width="100" height="98" align=
"middle"> Contours</h3>
<blockquote>
<p>DS9 can create and display contours as an overlay on an image.
The Analysis Contours menu is used to display contours. To create,
copy, paste, and configure contours, use the Analysis Contour
Parameters menu.</p>
<p><b>Contour Parameters</b></p>
<p>When creating a new contour, a dialog box appears, in which the
user selects the number of contour levels, smoothness, and the
distribution of the contours.</p>
<p><b>Contour Levels</b></p>
<p>Specifies the number of contour levels to be generated. A
typical number is between 1 and 10. Note: large numbers of contours
can take a long time to generate.</p>
<p><b>Contour Smoothness</b></p>
<p>Specifies how smooth the contours are. A smoothness level of 1
will evaluate the contour at each image pixel. A level of 2 will
evaluate the contour at every other pixel. The larger the number,
the quicker the contour will be generated, and the less detail will
be available.</p>
<p><b>Contour Scale</b></p>
<p>Specifies the distribution of the contour levels.<br></p>
<p><b>Contour Method</b></p>
<p>There are two methods that are available to calculate the
contour lines. The first, BLOCK, blocks down the image, by the
smoothness factor, before contours are calculated. As a result, the
larger the smoothness, the faster the result. The second method,
SMOOTH, smooths the image before calculating contours. As a result,
the larger the smoothness, the slower the result.<br></p>
<p><b><a name="ContourFiles" id="ContourFiles"></a>Contour
Files</b></p>
<p>A contour file is an ASCII file containing a header, global
properties, coordinate system, contour levels, and contour
points.<br></p>
<p><b>Header</b></p>
<p>A DS9 contour file may start with the following optional
header:</p>
<tt> # Contour file format: DS9 version
7.5</tt><br>
<p><b>Global Properties</b></p>
<p>Global properties affect all contour levels unless a line level
attribute is specified. The <tt>global</tt> keyword is first,
followed by a list of keyword = value pairs. Multiple global
property lines may be used within a region file.</p>
<tt> global color=green width=1 dash=1 dashlist=8
3</tt><br>
<p><b>Coordinate Systems</b></p>
<p>For each contour file, it is important to specify the coordinate
system used to interpret the contour points, i.e., to set the
context in which the positions are interpreted. For this purpose,
the following keywords are recognized:</p>
<tt> PHYSICAL # pixel coords of
original file using LTM/LTV<br>
IMAGE # pixel coords of
current file<br>
FK4,B1950 # sky coordinate
systems<br>
FK5,J2000 # sky coordinate
systems<br>
ICRS # sky coordinate
systems<br>
GALACTIC # sky coordinate
systems<br>
ECLIPTIC # sky coordinate
systems<br>
WCS # primary WCS<br>
WCSA # secondary WCS<br>
LINEAR # linear primary
WCS<br></tt>
<p><b>Contour Level</b></p>
<p>Each contour level is composed of a line value, line attributes
and one or more contours. Line attributes are specified at the
start of a new level and only affect contours within that level
.</p>
<tt> level=15.78775 color=pink width=2 dash=yes
dashlist=2 2</tt><br>
<p><b>Contour</b></p>
<p>Each contour is composed of one or more X,Y coordinates, with a
deliminator of space or comma, starting with "(" and ending
with ")". Contours are not closed.<br></p>
<tt> (202.4836468 47.22380226<br>
202.4833538 47.2239185<br>
202.4831634 47.22409874<br>
202.4829883
47.22428858)<br></tt><br></blockquote>
</body>
</html>
|
