Mercurial > hg > orthanc-stone
comparison OrthancStone/Resources/Documentation/Coordinates.txt @ 1796:20a0aba0ede5
creation of AnnotationsOverlay
author | Sebastien Jodogne <s.jodogne@gmail.com> |
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date | Wed, 19 May 2021 18:59:45 +0200 |
parents | 9ab251c03eda |
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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. |