71 lines
1.9 KiB
XML
71 lines
1.9 KiB
XML
<?xml version="1.0"?>
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<!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
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"file:///usr/share/xml/docbook/schema/dtd/4.4/docbookx.dtd">
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<chapter id="user-cp"><title>Control Points</title>
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<p>Control points are used for 2D and 3D alignment, and to constrain 3D scene
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models. Control point data is loaded from a control point file. Scripts to
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generate and manipulate control point files are included in the
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<code>scripts</code> directory of the source distribution; the file
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specification is outlined in the final section below.</p>
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<s><t>Loading a Control Point File</t>
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<p>The --cpf-load= option is used to load data from a control point file.</p>
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<pre>--cpf-load=<f> Load control point data from file <f> [0.8.1 and later]
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</pre>
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</s><s><t>Control Point File Format (version 0)</t>
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<p>The version 0 control point file format consists of a version command followed
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by a sequence of control points, with one control point per line of the file.</p>
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<pre>V 0
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<i>Control Point 1</i>
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<i>Control Point 2</i>
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<i>Control Point 3</i>
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.
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.
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.
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</pre>
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<p>Control points can be one of three types:</p>
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<s><t>Type A control points</t>
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<p>Type A control points specify a sequence of 2D points, one for each frame,
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where each point is specified as a pair of floating point numbers. If there is
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no data for a frame, then "nan" should be specified. E.g.:</p>
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<pre>A 20 30 nan nan 10 10 10 15
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A 23 22 25 25 nan nan nan nan
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</pre>
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</s><s><t>Type B control points</t>
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<p>Type B control points specify a 3D coordinate. E.g.:</p>
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<pre>B 10 30 -400
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B 10 15 -425
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</pre>
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</s><s><t>Type C control points</t>
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<p>Type C control points specify both 2D and 3D data. There is a single 3D point
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specified, as well as one 2D point for each frame. The 3D point appears at the
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end of the line. E.g.:</p>
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<pre>C 20 30 nan nan 10 10 10 15 10 30 -400
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C 23 22 25 25 nan nan nan nan 10 15 -425
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</pre>
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</s></s>
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</chapter>
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