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
|
<!--
//-----------------------------------------------------------------------------
// Copyright (C) 2002-2017 Thomas S. Ullrich
//
// This file is part of "xyscan".
//
// This file may be used under the terms of the GNU General Public License.
// This project is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License.
//
// Author: Thomas S. Ullrich
// Last update: Nov 15, 2017
//-----------------------------------------------------------------------------
-->
<html>
<title>Setting Markers</title>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<body style="font-family: Arial, Helvetica, sans-serif, Geneva">
<h2>Setting the Markers</h2>
<p></p>
<em>xyscan</em> does
not know anything about the content of the plot other than its size and
the color/gray value of each pixel. In order to make a <a href="coord.html">coordinate</a>
transformation, <em>i.e.</em> to
translate the position of the cursor from <a href="coord.html">local</a> (pixel)
to <a href="coord.html">plot coordinates</a>, it needs 4 positions (2 in <em>x</em> and 2 in <em>y</em>)
in plot <strong>and</strong> local
coordinates. From these, <em>xyscan</em> determines the transformation matrix.
From then on it is simple mathematics and <em>xyscan</em> will
display local and plot coordinates as you move the cursor over the plot.
<p>There are 2
markers (gray lines) for the x-axis, <em>x1</em> (leftmost-x) and <em>x2 </em>(rightmost-x),
and 2 markers for the y-axis, <em>y1</em> (lower-y) and <em>y2</em> (upper-y).
</p>
<p align="center"><img src="markers.png" width="523" alt="" border="1" /></p>
<p></p>
<p>To place a
marker, <a href="navigate.html">move the cursor</a> along the <i>x</i>-
or <i>y</i>-axis
and stop exactly at a point where you can clearly read of the coordinates
in the plot (typically a tic mark or the end of the axis). For
the x-marker it doesn't matter where you are in y, for the
y-marker the x position is not relevant.
</p>
<p>
After
you positioned the cursor press the <tt>Set</tt> button of the referring
marker in the <em>Axis Settings</em> tab in the Tool Box or alternatively
use a shortcut key (see below). An input dialog
pops up where you can enter position of the marker in
<strong><a href="coord.html">plot</a></strong><a href="coord.html"> coordinates</a>.
You can place the markers
in any order. If you feel a marker
is not properly placed you can set it again at any time. Once the
first marker is set the rotation angle of the plot or the scale (see <a href="stilted.html">Rotating
and Scaling Plots</a>) cannot be changed anymore.</p>
<p>Once all 4 markers are set,
<em>xyscan</em> will start to display the correct plot coordinates of the current cursor position
in the <em>Coordinates</em> tab.</p>
<p><strong>Hint</strong>:
the further away <i>x1</i> and <i>x2 (y1 </i>and<i> y1) </i>are from each other the
higher the precision of the scan.</p>
<h3>Useful Shortcut Keys</h3>
Ctrl+1
(macOS: ⌘+1): set lower x marker<br />
Ctrl+2
(macOS: ⌘+2): set upper x marker<br />
Ctrl+3
(macOS: ⌘+3): set lower y marker<br />
Ctrl+4
(macOS: ⌘+4): set upper y marker<br />
</p>
</body>
</html>
|
