Blog | The Triangular Method Tool
In this post, we review the Triangular Method tool. This tool makes it easy to import scene data documented using 2 reference points.
Let’s suppose our scene data was collected by measuring the linear distance from witness marks to reference point 1 (RP1) and reference point 2 (RP2). The distances are shown in the table below.
Here we see the two reference points defined in our scene.
Select Create > Helpers 2D > Triangular Method.
Next, left-click and hold on reference point 1. Drag the mouse cursor to reference point 2 and release. Drag the mouse cursor away from the two reference points and left-click once again. This will create a triangle. Open the “triangles” menu, to reveal the “triangles” list. So far, there is only a single triangle defined. “edge a” corresponds to the distance between two reference points. You can type in the measured value if needed. Next, type in the measured distances between RP1 and your witness mark (here side b), and do the same with respect to RP2 (here side c).
Note, the control vertex for the measured point can be moved with the mouse, while keeping the first two points, at RP1 and RP2, fixed.
Because defining 3 triangle edge lengths leaves a mirror symmetry ambiguity about side “a”, you may need to enable or disable “reverse” depending on which side of side “a” the witness mark lies on.
Next, we left-click on “add to edge a” to add a new triangle, keeping side a’s vertices fixed to our two original reference points. When we left-click on “add to edge a”, we see a new triangle appear in the “triangles” menu. Here “triangle 2” will be used to place point B in our scene. Note, we have the option to place evidence relative to other evidence measured in the scene, rather than using only 2 fixed reference points. This is accomplished using either “add to edge b” or “add to edge c”.
Next, we add our data for point C.
Finally, we add our data for point D.
Comparing our triangulated points to our test data, we see good agreement.