Modifying Contours

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Modifying contours

Once contours are drawn, you can reposition, resize, or reshape them. You can also trim anchor points.

Repositioning contours

You can reposition a single contour or a group of contours. Follow the instructions below.
To reposition a single contour
Select the contour and drag it to the new location.
To reposition a group of contours
1 Hold down the Shift key as you click one of the contours in the group. All of the other contours in the group are also selected.
2 Continue to hold down the Shift key as you drag the contour group to the new location.

Resizing contours

You cannot collectively resize a group that consists of multiple contours; each contour must be resized individually. Except for point VOIs, you can resize any contour shape. For lines, only the length can be changed; the width cannot. To resize lines, go to [MIPAV_Segmentation.html#1392637 ``To resize contours''].

Before you can resize them, all contour shapes except lines must be surrounded by a bounding box. See also the following section [MIPAV_Segmentation.html#1347914 ``To turn the bounding box on''].
To turn the bounding box on
1 Do either of the following:
Select the contour and then select VOI > Properties in the MIPAV window.
Right-click the contour. A menu appears. Select Properties.
The VOI Statistics dialog box opens. See also [MIPAV_Analysis.html#1362684 Figure 196 on page 311].
2 Select Show contour bounding box.



3 Change, if you want, any of the other information in the dialog box.
4 Click Apply.
5 Click Cancel to close the dialog box.
To turn the bounding box off
1 Do one of the following:
Right-click the contour. Select Properties from the pop-up menu.
Left-click the contour. Select Properties from the VOI menu in the MIPAV window.
The VOI Statistics dialog box appears. See also [MIPAV_Segmentation.html#1344987 Figure 174].
2 Clear Show Contour Bounding Box.
3 Click Apply.
4 Click Cancel to close the window.
To resize contours
1 Select the contour. The bounding box appears ([MIPAV_Segmentation.html#1344987 Figure 174]) around the shape. (For rectangle contours, the bounding box and rectangle legs may overlap.)
2 Click Cancel to close the window.

Figure 174. A VOI bounding box and the VOI Properties dialog box


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3 Do one of the following:
To resize lines: Click an edge or corner of the shape. Drag until the shape is the desired size.
To size other shapes: Click one of the bounding box handles. Drag the handle until the shape is the desired size.

4 Choose whether to continue showing the bounding box.
Note: If you want to reposition or add an anchor point, turn the bounding box option off.

Reshaping a contour

You reshape the contour by adding or repositioning anchor points. Instructions for adding and repositioning anchor points follow.
To add anchor points
1 Click the contour to select it. The anchor points become visible.
2 Click the place where you want to add the new anchor point. The new anchor point appears.
To reposition anchor points

You can reposition a single anchor point at a time. If you need to redraw a portion of the contour, MIPAV allows you to reposition several contiguous anchor points with one motion of the mouse.

1 Select the contour. The anchor points become visible.
2 Position the pointer over the anchor point or points that you want to reposition. The pointer changes to the shape of a hand with the index finger extended.
3 Do either of the following:
To reposition a single anchor point: Drag the anchor point to the new location.
To reposition several anchor points: Hold down the Alt key as you drag the anchor points in the counterclockwise direction to their new locations.

Retracing a VOI contour

To retrace a VOI contour do the following (see [MIPAV_Segmentation.html#1657248 Figure 175]):
1 Select an existing VOI;
2 Hold the ALT key and use the mouse to pick up a point on the VOI;
3 While holding both the ALT key and left mouse button, move the mouse clockwise to redraw the VOI;
4 Stop moving when you reach the last point which you would like to redraw.
Figure 175. Retracing a VOI contour


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Trimming VOI anchor points

MIPAV can automatically trim anchor points from the contour. In the trimming process, unnecessary anchor points are pruned. For example, if three anchor points are on the same line, the middle anchor point is deleted. Since only two anchor points are needed to indicate a line, the middle anchor point is extraneous. The trim parameter defines what is meant by the same line. Setting this value to zero causes only unnecessary anchor points on a straight 180-degree line to be pruned. Setting a higher value prunes all but the sharpest corners of the contour.
To trim anchor points
1 Select the contour you want to trim.
2 Select VOI > Trim Parameter in the MIPAV window. The VOI Trim Parameter dialog box ([MIPAV_Segmentation.html#1011435 Figure 176]) opens.
3 Move the slider to the desired number.
Figure 176. VOI trim parameter dialog box

Trim parameter
Specifies the number of anchor points you want the software to trim from the contour.
Setting this value to zero causes only unnecessary anchor points on a straight 180-degree line to be pruned. Setting a higher value prunes all but the sharpest corners of the contour.

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Trim adjacent points

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Trims points that are adjacent.

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Apply

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Applies the parameters that you specified.

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Close

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Disregards any changes that you made in this dialog box and closes the dialog box.

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Help

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Displays online help for this dialog box.

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