There are two facilities for locating and label points on images. The points utility locates a point in three dimensions in a stacked image set. The point will show up in any image that intersects the point and will show on 3d views. The label for a point will appear close to the point. Points are also used in image fusion. Points are positioned with a left mouse click.
Labels are specific to a plane. For a stacked image set, the label will appear any time the plane is displayed. On other images not part of a stacked image set, the labels are specific to the particular image. The text for the label may be placed away from the point with a line drawn to the point. Labels are position with a button down drag release sequence with the left mouse button.
A markers is a sequence of connected points. The marker is assigned a radius and is represented graphically by a cylinder which following and centered on the points, with joints at the points. A marker consisting of a single point is drawn as a sphere.
The Points Toolbar and Locate Popup Control
Points here are like labels, but the label stays close to the position of the point and is displayed in both 2-d planes and 3d views of the stacked image set. To be displayed in a 2d view, the plane of the 2d view must intersect the volume of the point. The point is drawn smaller as the plane intersection approaches the edge of the point. The distance the point is from the plane to be drawn is a parameter that can be set separately. Points are displayed as spheres when they are large enough. On 2d views they will be circles. On 3d views, small points will take a diamond shape.
The points toolbar is selected from the Stacked Image Set pulldown on the main toolbar. Select Options and then click on Points on the Options toolbar.
Click the mouse on any plane image for the chosen stacked image set. A temporary mark will appear at the position of the mouse click. You may move this point simply by clicking again.
You must than enter a point name. This is the label that will appear at the position of the point. Note also that a file name is made out of this label be replacing spaces with underscores. Each label must have a unique file name. The program will not allow you to create a point name that results in the same file name of another point.
Select the diameter of the point with the slider. Larger points will show up better on 3d views but may be obstructive on 2d views. For this reason the diameter of the point that is drawn is specified separately for 2d and 3d views. A 2d view is an image, whereas a 3d view is a perspective view.
Because we are here defining a point in the three space of the stacked image set, another issue for 2d views is how far can the point be from the plane before it is drawn. The minimum tolerance is 0.05 cm, to guarantee that round off error will not prevent a point from showing up when the distance from the point to a plane is computed. Another plane that comes within this distance of the point will also draw the point. However, the distance from the plane will reduce the radius that is drawn accordingly. The radius of the intersecting circle with the plane is used. A plane beyond the radius of the point will not draw regardless of the distance parameter. There may be reasons why you would want to increase this tolerance, but normally you would not want to change it.
Also for 2d drawing, you can specify a circle instead of a filled circle. And you can then specify the line thickness of the circle. This may be useful for outlining some particular point.
Note that control is available to control whether points are drawn in 2d views separate from 3d views, under Control of the points tool bar below.
You must also select a color for the point. Once a color has been selected, you may continue to use the same color for other points that you create without having to reselect the color.
To create the point whose specifications you have created, you must hit the Accept Point button. Otherwise hit Dismiss to cancel or when you are done creating points.
After a point is created and located, you may edit its characteristics such as size and color and the text for the label. The only thing you can’t do is move the point. To move a point delete it and create a new one. Select Edit on the Points toolbar. Then select the point from the list of points. The edit tool will then pop up. To change the color of a large number or all points, use the Control Points tool below.
Select Delete on the points toolbar. You will be presented with a list of points. Click the mouse on the items you want to delete and then hit the Delete Selected Items button. There will be no further confirmation.
The control panel will allow you to turn on and off a point in all 2d and 3d windows. This choice will not persist across termination of the program. By default all points are shown.
However, a mechanism is provided to change the color of selected or all points. The color assignment will persist.
The labels toolbar is found under the Images pulldown on the main menu.
Here you can label specific locations on an image. The label consist
of a line pointing to a location, that leads to a label.
The label will only appear on the image you have labeled, or any other copies that you choose to display. Use Points for locating points in a stacked image set that you want to see in 3d views. Here labels are specifically only for two dimensional images.
(1) Type in the text for the label in the text field provided.
(2) Choose a color by hitting the Choose Color button. Once a color is chosen, it remains for all additional labels you may create.
(3) Hit the Locate button. Then with the mouse, click and hold down the left mouse button on the point that you want to point to. While continuing to hold down the mouse, drag to the location where you want the label to appear. When you release the mouse you will have created a label.
(1) Hit the Select button. Then click the left mouse button on an existing label. Aim for the line connecting the point to the label. The label should change color. If you have selected the wrong label, simply hit the Select button again.
You can now do one of three things, change the text, change the color,
or change the location.
1. To change the text, simply edit the text field and hit the return key.
2. To change the color, simply hit the Choose Color button and select a new color.
3. To change the location, simply hit the Locate button and follow the rest of step (3) above for a new label.
(1) Hit the Select button and select the label by following the rest of step one above for changing an existing label.
(2) Then hit the Delete button. A prompt will be made to confirm your choice to delete.
Distances between points can be found with the distance function. Under Stacked Image Sets the distance between two points can span across images in the image set. That is, one can click the mouse to locate one point on any image in the image set, and click the mouse to locate the second point on any other image in the image set. Under the Images pulldown, both points must lie in the same image.
Note that the distance computed between two points is dependent upon the pixel size read in the image file.
This is accomplished on the Fusion Options toolbar under Stacked Image Sets on the main tool bar.
Copying Points Between Fused Image Sets.
On the popup tool, select the image set that the points are to copy to. Then select the image set that the points are to copy from. The points in the copy from image set will be listed in the scrolled list area. Select the points that you want copied. Note however, that if a point with the same label all ready exist in the copy to image set, that that point will not be copied. Each point, once copied, will become part of that image set’s list of points independent of the point in the image set it came from. The points will be drawn in the image set along with all the other points in that image set. In the copying process, the coordinates of the point will be transformed from the coordinates in the copy from image set to the equivalent location on the to image set using the fusion solution. Any future change in the fusion solution will not effect the location of this point. The point will remain fixed until you delete it.
The marker toolbar is selected from the Stacked Image Set pulldown on the main toolbar. Select Options and then click on Markers on the Options toolbar. The marker toolbar with the Locate popup is shown below:
You can trace out and locate a marker with the mouse, edit some properties of the marker, delete markers, and control their display in 2D and 3D views.
The marker is located by clicking the left mouse on each successive point starting at one end of the marker and proceeding to the other end, although a marker can consist of a single point. Dragging the mouse is not supported.
For a physical object:
If the marker intersects CT scans at a single point, then follow the marker through the CT scans, clicking the mouse once on each CT scan at the intersection point (you might have to first select the frame with the mouse). If the marker appears in the plane of a CT scan, follow that section on the CT scan, using judgment as to when the marker center has crossed into the next CT scan space. For a brief section, the center point may be sufficient.
The marker is assigned a label which will appear with the marker in a particular 2D plane or at the beginning in a 3D view. Marker labels must be unique. The marker label is used for the file name to save the marker and the text may be changed to produce a legal file name.
The tolerance distance for the sequence is for the construction of the surface of the marker at a given radius. Intermediate points are omitted if the distance of a point from the line connecting an earlier and later point is less than the tolerance distance.
The line width selection controls the width of the line in 2D renderings and 3D wire frame renderings.
The “Solid Fill/Wire” toggle button controls whether the marker is solid filled on 2D renderings or just a wire outline.
The marker diameter controls the diameter of the rendered marker in 2D and 3D renderings.
The color controls the color of the marker.
To enter a marker, hit the "Start Marker" toggle button and begin to click the left mouse, starting at one end and proceeding to the other end. The middle mouse button will back up one point at a time or use the "Backup" button on the locate popup. The "End/Save Marker" is used to close the marker and save it in a file. The right mouse button will also close and save the marker. A point is not added with the right mouse button. But with the “Enable Zoom with Mouse” button in, the middle mouse and right mouse will invoke the zoom function of the image frame rather than backup one point or end the trace. Leave the Enable Zoom button in if you need to zoom in on a particular spot. The middle mouse button with zoom in the image with the center where you click the middle mouse button, the right mouse button will zoom out. You can change the Enable Zoom button during a trace.
The Cancel Marker button can be used to cancel a marker that has been started. Cancel is also effected by unselecting the start toggle button.
All the properties of the marker can be edited except the position of the points that define the marker. Delete the marker and reenter it to change the points.
You can select markers to delete.
You can select specific markers to turn on and off in 2D and 3D views, and you can change the color of all selected markers as a group. There is otherwise no individual frame control for a marker.