3rdTech DeltaSphere-3000 User Manual page 71

DeltaSphere-3000 3D Scene Digitizer
Note: If you don't save the spatter group in the scene you need not save
the changed file. However if you do save the spatter group you should also
save the data or the group will no longer match the data in the scene and
problems can occur.
Zoom in to a spatter drop you want to include in this group. Hold Ctrl and draw 2
measure lines on the drop – one identifying the long axis and one identifying the
short axis (in either order) as shown in Figure 50. After doing this for at least 2
spots, additional lines will appear: 1) a white line through the major axis, in the
plane of the surface, for each spot, 2) a blue line perpendicular to the plane through
the point that is the average of the intersection points of the white lines, and 3)
purple lines representing the calculated trajectory to each blood spatter spot. The
results from the 3 spots identified with landmark points in your sample data are
shown in Figure 51.
Note: When drawing the 2 axis lines you may notice that one or both of
them may be only partially visible. This is because they lie exactly in the
plane of the surface and can be obscured by the data.
Figure 50 Blood spatter measure lines
Note: When zooming in very close to model data you may find some of
the data disappearing. There exists a clipping plane called the 'Near Plane'
and as you zoom in, data that gets closer than that plane disappears – or
gets 'clipped'. You can adjust this using the Viewing Parameters Toolbar
(See 13.8). Select Near Plane Distance and make the number smaller than
its default (which is 1). This will enable zooming in closer without
clipping.
Note: Selecting two drops whose major axes are nearly parallel can make
their 'white lines' converge well away from the appropriate spot. Care
should be taken to choose drops that converge near the same point – and
to delete choices that do not.
70 9/23/05