Locate3D Overview: Difference between revisions
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'''Load Subject...''' (Ctrl + O): loads a Subject file. | |||
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'''Save Subject''' (Ctrl + S): saves the currently loaded subject to its existing Subject file. | |||
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'''Save Subject As...''': saves the currently loaded subject to a new Subject file. | |||
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'''Save POI Locations...''': saves three text files containing the coordinates of the current object’s POIs. The files are as follows: | |||
#one with the 3D coordinates in the X-ray reference frame of all POIs for all frames, | #one with the 3D coordinates in the X-ray reference frame of all POIs for all frames, | ||
#one for the first view with the 2D POI coordinates in the image frame of the view, and | #one for the first view with the 2D POI coordinates in the image frame of the view, and | ||
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If a name for any of these files is already specified in the subject file, it is used to write the data to. If the file already exists, it is overwritten without notification. For any that is not specified, a file browser is displayed, allowing you to select the file and folder. | If a name for any of these files is already specified in the subject file, it is used to write the data to. If the file already exists, it is overwritten without notification. For any that is not specified, a file browser is displayed, allowing you to select the file and folder. | ||
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'''Save Pose Maps''': saves the pose map of each selected object in the current trial to a .csv file. This file contains 6 values for each pose: the XYZ translation and the XYZ Euler angles representing the transform from the X-ray lab frame to the object's local coordinate system (i.e., as if you were traveling from the lab frame to the object frame). If a name for the pose map file is not already specified in the subject file, you will be prompted to browse for the file to create. A link to this file will then be added to the subject file. Before the poses can be saved, they must be calculated using the ''Compute Object Poses from POIs'' command. | |||
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'''Save Pose Maps As...''': saves the pose map for each selected object in the current trial to a new .csv file. You will be prompted to browse for a new file for each object. A link to this new file will then be added to the Subject file. | |||
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'''Save Object Transforms...''': saves the pose map of each selected object in the current trial to a .txt file. This file contains a 4x4 transform for each pose, expressing the transform from the X-ray lab frame to the object's local coordinate system (i.e., as if you were traveling from the lab frame to the object frame). If a name for the transforms file is not already specified in the subject file, you will be prompted to browse for the file to create. A link to this file will then be added to the subject file. Because these transforms are calculated from the object poses, the ''Compute Object Poses from POIs'' command must be used before the transforms can be saved. | |||
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'''Save Landmark Locations...''': saves a text file with the 3D coordinates of all landmarks on the current object for all frames that have poses. These locations are calculated using the object poses, so the ''Compute Object Poses from POIs'' command must be used before the landmarks can be saved. If a name for the landmarks file is not already specified in the subject file, you will be prompted to browse for the file to create. A link to this file will then be added to the subject file. | |||
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'''Exit''': exits the program and all unsaved data will be lost. The program can also be closed by using the X in the top right corner of the program window. | |||
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Revision as of 16:43, 18 June 2020
Language: | English • français • italiano • português • español |
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Locate3D tracks radiopaque beads in X-ray trials. It is most often used to track objects (e.g., bones and implants) with implanted beads. If the object contains three or more beads in fixed locations, and these 3D locations are known relative to the object's CT coordinate system, then the beads' 2D locations in the X-ray images can be used to calculate the object's 3D pose in the X-ray lab frame. Locate3D is thus similar to X4D, except that it uses multiple beads to determine the pose of an object, instead of the contours of the object itself. Locate3D requires that the configuration of the X-ray equipment has been calculated (with CalibrateDSX), and that the locations of the beads in the object's local frame have been determined (with Surface3D).
Digitizing POIs |
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To digitize a POI for the current reporting time, select the POI by clicking on its name in the table in the Points of Interest widget. The table row will be highlighted in blue, and when you move the cursor into one of the X-ray windows, the cursor will change to a circle inside a square, with the POI name to the right. The circle represents the expected size of the POI on the X-ray image, which is dependent on the pixel size of the image and the radius of the POI, which is specified in the subject file. The square represents the region of the image that will be searched for the center of the POI (some of the outer pixels of the POI can be outside the square). The size of the square is controlled by the Click Search Factor parameter. A larger number makes it quicker and easier to digitize POIs, but you don't want the square to contain more than one POI. When you click the left mouse button, Locate3D will search the X-ray pixels within the square to determine which one is the best candidate for the center of the POI. This is done by using the Centroid Threshold parameter to separate the POI pixels from the background, and the Edge Threshold parameter to determine if these pixels represent a circular POI. The POI is assumed to be a bright circle on a dark background, with the center of the POI being the brightest. The 2D coordinates of the POI center in each view are calculated as the weighted center of the pixels above the Centroid Threshold. Once you digitize the POI in one view (you can start with either one), a yellow line is drawn in the other view. This line is the projection of the point in the first view through the field of view of the second view, and its purpose is to help you identify the POI in the other view. You can then digitize the POI in the second view by clicking on a point near the line. If you make a mistake identifying the proper POI in the first view, you can press the Esc key to cancel the process. If you make a mistake after identifying the POI in the second view, you can remove the POI pose by unchecking the pose box in the POI table. Once you have digitized a POI, Locate3D automatically advances the current POI to the next one in the table that does not already have a pose. Once you have identified the POIs for one or more reporting times, you can have Locate3D attempt to automatically identify them for other reporting times using the Propagate POIs command in the Tools menu. See the wiki entry for this command for more details. |
Tutorials
How To: Track Objects Using Points of Interest
Menus
File Menu |
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Tools Menu |
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Options Menu |
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Help Menu |
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Widgets
DSX Configuration | ||||||||||
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Points of Interest | ||||
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POI Parameters | ||||||||||||
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The POI Parameters widget displays the parameters that govern the digitization of POIs in the X-ray images.
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POI Graphs |
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The POI Graphs widget displays graphs of the X, Y, and Z coordinates of the selected POIs for the current trial. As the cursor is moved around the graph a crosshair shows the current coordinates. If the cursor is close enough to one of the data points for a POI it will snap to it and display that point's coordinates in the POI's color. To move the view of a graph in the Y direction, press the left mouse button and drag the cursor up or down. The mouse wheel can also be used to zoom the graph in the Y direction. Press the R key to reset the graph to the default view. The X axis of the graphs cannot be changed. Data points cannot be added or moved via the graphs, but they can be deleted. To select one or more points, press the Ctrl key and then box-select them (hold the left mouse button down while sweeping the diagonal of a box with the cursor). Press the Delete key to delete the points. Press the Esc key to deselect them. |
X-ray Windows |
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The X-ray windows display the X-rays of each view, as well as POIs, POI trails, reference frames, and landmarks. The Points of Interest widget lets you choose which POIs and POI trails to display on the X-rays. The View menu has commands for toggling the display of the reference frame and landmarks of the current object, and the POIs of all of the other objects. The following mouse and keyboard commands can be used in the X-ray windows:
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Settings |
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