Sensors & Software Inc. NG250 ユーザーズマニュアル
Noggin
12-Survey & Map Mode
99
12.3.4.2 Survey Format
The Survey Format specifies how the lines will be collected. The lines shown in Figure 12-11,
Figure 12-12, and Figure 12-13 are all collected in the Forward direction only. This means that
each line starts at the X or Y baseline.
Figure 12-12, and Figure 12-13 are all collected in the Forward direction only. This means that
each line starts at the X or Y baseline.
When the length of the survey lines are more than about 20 metres, data acquisition speed may
be increased by collecting every second line in the reverse direction (Figure 12-14, Figure 12-15,
and Figure 12-16). This is called a Forward and Reverse survey format.
be increased by collecting every second line in the reverse direction (Figure 12-14, Figure 12-15,
and Figure 12-16). This is called a Forward and Reverse survey format.
Using forward and reverse format can speed acquisition but can lead to mapping artifacts called
“herringbone” if there are positional errors. It is important that the odometer is calibrated (Section
12.5.2: P.110), the Grid Dimensions are correct (see Grid Dimensions on page 101) and that
lines are always collected starting on a baseline.
“herringbone” if there are positional errors. It is important that the odometer is calibrated (Section
12.5.2: P.110), the Grid Dimensions are correct (see Grid Dimensions on page 101) and that
lines are always collected starting on a baseline.
X Lines Only – Forward and Reverse
Using the Forward and Reverse survey format, X line data are collected in the pattern shown in
Figure 12-14.
Figure 12-14.
Figure: 12-14 For collecting GPR data consisting of long data lines it makes more sense to follow a
forward and reverse surveying pattern. For the final data to be spatially correct with a minimum of
editing, data collected in this pattern should be on lines that extend completely from one baseline to the
other.
Y Lines Only – Forward and Reverse
Using the Forward and Reverse survey format, Y line data are collected in the pattern shown in
Figure 12-15.
Figure 12-15.
When data are collected like this, it is important that lines start and end on established baselines,
otherwise, when lines are reversed to the correct orientation for the display, they may be offset
from one another.
otherwise, when lines are reversed to the correct orientation for the display, they may be offset
from one another.