viewpoint in the scene tree, and selecting
Set Viewpoint Direction
. In the future that will be the
starting direction for the viewpoint.
To unlock the viewpoint, choose either
Move Object
mode, or
Fly
mode from the View menu.
Both also have keyboard shortcuts (‘t’ and ‘y’).
8.2.2
Blood Spatter Tool
The Blood Spatter Tool produces 3D lines representing the trajectories of blood spatter. The
tool is based on the known characteristics of blood spatter as described in several texts. It
currently works only with spatter on a flat surface – like a wall or floor – and only in model
data.
Note: You will typically want to have a high-resolution photo inset to work with.
See section 12.2 for more information on high-resolution insets. We’ve already
created one in the sample data.
Using the tool is a simple multi-step process:
•
Identify the plane to be used by outlining the region
•
For each of 2 or more spatters, identify the long and short axes by drawing lines
In the sample data set there is a wall near the ‘victim’s’ head with simulated blood spatter with
which you might want to experiment. We’ve identified blood spots with landmark points – but
you can use any that you think appropriate.
First select the blood spatter tool (
) from the toolbar. This starts a ‘wizard’ to lead
you through the steps.
Choose a name for the spatter group. A spatter group will be several spots you
believe come from approximately the same point in space, e.g. the lines of their
major axes will intersect in the plane.
Outline a region of the flat surface that encompasses all the points you may use as
described in section 8.1.5. (If you have already identified a region previously, you
can select this region instead of creating a new one.) If you’re using data with a
high-resolution inset, you should try to outline an area slightly larger than the inset
for the best results. This tool does not change the color of the plane, but it does leave
the center and four corner points of the plane visible.
Note: Because blood spatter analysis requires very precise calculations,
this action not only creates a plane fit to the points – but actually edits the
data, moving the points to lie on the plane. These are very small
adjustments and serve to increase the accuracy of the final analysis. If you
would like to save these changes to the data, you can do so with the File
menu command,
Save File as
– and give the model file a new name. If
you do not save the file and try to save the scene you will be notified that
the data has changed. If you then continue to save, it will save the changed
data overwriting the existing model data. Note that this does not change
the original scan (RTPI) data – only the created model file.
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