The `Object selection' panel allows you to segment multiple objects in the same 3D ultrasound data set. The panel's default appearance is shown above: it allows you to select any one of ten objects and set various attributes including its name and colour. For example, supposing you select `object 1' as above. With this selection, any segmentation contours you define in the `Review' window will be associated with `object 1' and not any of the other objects. The contours will be drawn in cyan in the `Review' and `Outline' windows, and any corresponding surface will be displayed in opaque cyan in the `Surface' window. Once you've finished segmenting the object, and before you save the segmentation file, you may wish to change the object's colour and opacity by adjusting the sliders in the `Object selection' panel. You can also give the object a name by deleting the text `object 1' and replacing it with something more descriptive, like `foetus' for example. The names and colours are stored in the segmentation file along with the contours themselves, so next time you load the segmentation the correct names and colours will be restored automatically.
Here's an example where we have segmented and named three objects: a foetus, placenta and umbilical cord. Selecting `foetus', we get to see (and adjust, if required) the colour of the contours (red, green, blue) and the opacity of the corresponding surface in the `Surface' window (alpha). We also get to see that the foetus is `closed'. If we'd segmented a blood vessel, we may wish to leave it open so we can peer inside it in the `Surface' window.
Here's one B-scan in the `Review' window, showing some contours belonging to `foetus'. Since `foetus' is currently selected in the `Object selection' panel, the contours are shown as continuous, not dashed, lines.
Here's the `Outline' window, showing the contours belonging to the foetus, placenta and umbilical cord. Since `foetus' is currently selected in the `Object selection' panel, its contours are shown as continuous lines. However, the contours corresponding to `placenta' and `umbilical cord' are dashed. The volume at the bottom of the window is that of the foetus, since that is what's selected in the `Object selection' panel.
Now suppose we select `placenta' in the `Object selection' panel, as below.
Here's the `Review' window again. Note how the contours are now dashed, since these contours do not belong to the currently selected object. If necessary, you can change which object a contour belongs to: clicking near a contour with the left mouse button reassigns it to the currently selected object (unless you're doing a grass-fire segmentation using the threshold sliders, in which case a left mouse click is used to ignite the fire).
Here's the `Outline' window again. This time the foetus and umbilical cord are dashed, and the volume is that of the placenta, since `placenta' is selected in the `Object selection' panel.
Finally, here's the `Surface' window, showing all three objects. The volume is that of the placenta, since `placenta' is selected in the `Object selection' panel. Note the effect of each object's `alpha' (transparency) attribute. The alpha values have no effect in the `Outline' and `Review' windows, except that an alpha value of zero renders the corresponding contours invisible in the `Outline' window.