Figure 5-38.--Resection.
STRAIGHTEDGE METHOD.-- Study the
resection (fig. 5-38). Resection can be done with or
without a compass.
following steps to locate the unknown position of the
user by the straightedge method:
MAP AND COMPASS METHOD.-- Study the
following steps to locate the unknown position of the
1. Orient the map on a flat surface by the inspection
user by the map and compass method:
method.
1. Orient the map using the compass.
2. Locate two or three known positions on the
2. Locate two or three known positions on the
ground and mark them on the map.
ground and mark them on the map.
3. Lay a straightedge on the map with the center
3. Measure the magnetic azimuth to a known
of the straightedge at a known position as a pivot
position; convert it to grid azimuth.
point. Rotate the straightedge until the known position
4. Change the grid azimuth to a back azimuth and
on the map is aligned with the known position on the
draw a line on the map from the known position back
ground.
toward your unknown position.
4. Draw a line along the straightedge away from
5. Repeat Steps 3 and 4 above for a second known
the known position on the ground toward your
position.
position.
6. For a check on your accuracy, repeat Steps 3 and
5. Repeat Step 3 above using a second known
4 above for a third known position.
position; and as a check on your accuracy, repeat Step 3
7. The intersection of the lines is your location.
above, using a third known position.
Using three lines, a triangle of error maybe formed. If
6. The intersection of the lines is your location.
the triangle is large, recheck your work.
5-28
