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comparison OrthancStone/Resources/Documentation/Coordinates.txt @ 1796:20a0aba0ede5

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creation of AnnotationsOverlay
author Sebastien Jodogne <s.jodogne@gmail.com>
date Wed, 19 May 2021 18:59:45 +0200
parents 9ab251c03eda
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1 1
2 Some notes about the coordinate systems 2 Some notes about the coordinate systems
3 ======================================= 3 =======================================
4
5 Different systems
6 -----------------
7
8 * "World" coordinates refer to (x,y,z) positions, typically expressed
9 in millimeters (according to the DICOM conventions), which allows to
10 define volumes and 3D cutting planes.
11
12 As explained below, those coordinates actually correspond to
13 "patient" coordinates if rendering DICOM images.
14
15 The "world" coordinates are *not* used by the Stone Web viewer,
16 because the latter is a 2D application.
17
18 * "Scene" coordinates refer to (x,y) positions, typically expressed in
19 millimeters (as a byproduct of world coordinates), which allows to
20 define the 2D geometric elements that are part of the scene, and
21 Y-axis pointing downward.
22
23 * "Canvas" coordinates refer to (x,y) subpixel positions that will be
24 blitted by a compositor onto a drawing canvas. The units are
25 floating-point pixels, with (0,0) corresponding to the center of the
26 display surface, and Y-axis pointing downward. The "canvas"
27 coordinates modify the "scene" coordinates according the zoom/pan
28 specified by the user.
29
30 * "Pixels" coordinates refer to standard integer (x,y) coordinates of
31 the surface in memory. (0,0) is the top-left pixel.
32
33
34 Relations between 2D and 3D
35 ---------------------------
4 36
5 * The 3D coordinates are expressed in the PATIENT system, *not* the 37 * The 3D coordinates are expressed in the PATIENT system, *not* the
6 "gantry" coordinates. As a consequence, the tags "Image Position 38 "gantry" coordinates. As a consequence, the tags "Image Position
7 Patient" (0020,0032) and "Image Orientation Patient" (0020,0037) 39 Patient" (0020,0032) and "Image Orientation Patient" (0020,0037)
8 describe the 3D geometry of a slice. 40 describe the 3D geometry of a slice.