GSSI SIR 20, Руководство пользователя

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Geophysical Survey Systems, Inc. SIR® 20
Manual
MN92-078 Rev F 27
Chapter 3: Setting Up your System
for 3D Data Collection
This section presents instructions for configuring your SIR 20 to collect a block of 3D data. Data
collection may be in GPS, belt or survey wheel mode. You should first read though the previous section
on 2D data collection and understand basic 2D before attempting to collect 3D data.
Collecting data for 3D imaging is easiest when you have a guide grid laid out to follow. You should lay
out a grid with chalk, paint, ropes, or survey flags or stakes. Your grid can be any size, but your data
quality will be much better if you make sure that your grid corners are square. Your grid itself does not
have to be a square, it can be a rectangle, or can be irregularly shaped, If you follow the tips below, the
pre-survey gridding process will be greatly simplified.
Tips for Grid Setup
•
If you are scanning in a normal profile order (one direction only), you need the grid edge that you
start your profiles from (the baseline) to be straight. We understand ‘one direction only’ to mean
scanning along either the X or the Y axis, but not both. A ‘normal’ profile order is one where you
are collecting data along your profile in one direction. In other words, you start at the baseline,
collect data until the end of the line, pick up the antenna and move it back to the baseline to collect
the next profile in the same direction. This is different from the zigzag method, where you are
simply turning around and collecting the next data file in the opposite direction from the previous
one. If you are collecting in a zigzag order, both the start and finish baselines should be straight.
•
Your grid can be irregular, but as long as the line that your profiles start from is straight, the
RADAN software will have no problem creating
parallel profiles.
•
Make sure that your grid corners are right angles
and that your grid lines are actually perpendicular
to your baseline. The graphic at the right
illustrates how to put together a square, 10×10
grid.
1
Locate the origin point (0,0) and pull a tape
measure 10 to find the point 10,0
(blue line: a). This is your baseline.
2
Pull one tape measure 10 from 0,0 (line b) to 0,10.
Pull the other one from
10,0 to 0,10 (line c).
3
Move both tapes together so that 10 on line b connects to 14.14 on line c. The point that they connect
is the grid corner. You will know that the corner at 0,0 is square because this method produces a right
triangle.
4
Repeat for the corner 10, 10.