Real-Time Visualization and Geometry Reconstruction of Large Oil and Gas Boreholes Based on Caliper Database - Visual Computing: Scientific Visualization and Imaging Systems - page 235

Fig. 13.6 Top View of the
Caliper tool inside a well bore

Table 13.2 How to calculate
the X and Y coordinates

Data X-Value formula Y-Value formula

Arm C1 P1 cos 0 P1 sin 0

Arm C2 P2 cos 300 P2 sin 300

Arm C3 P3 cos 240 P3 sin 240

Arm C4 P4 cos 180 P4 sin 180

Arm C5 P5 cos 120 P5 sin 120

Arm C6 P6 cos 60 P6 sin 60

13.3.3.2 Interpolation of the Data with Splines to Obtain
a Section with the Desirable Resolution

Given six 2D control points (obtained from the Caliper's arm data) instead of
simple connect the points (red lines in Fig. 13.7 ) a smooth curve is created (black
lines in the same figure) to interpolate them using a closed natural cubic splines
algorithm. An interesting demonstration can be found in [ 10 ].

13.3.3.3 Inclusion of the Rotation in P1AZ

The interpolated points are rotated around the section center in the Y-axis. The
rotation angle is defined by the P1AZ value read by the sonde. This aligns the first
arm with the earth's magnetic north.