and delete any rows you don’t wish to include in the
analysis (Figure 12).
I deleted the rows where my altitude was low as I was
taking off and landing. We don’t want to contaminate our
grid with oversampling at those locations!
Next, head over to www.qgis.org and download the
free QGIS application. This will be familiar to those of you
that followed along when we were looking at
photogrammetry data. Follow the installation instructions
and fire up QGIS (Figure 13). Head up to
the Layer menu and find the Add Delimited
Text Layer option (Layer -> Add Layer -> Add
Delimited Text Layer...). Click the browse
button and find your file.
QGIS is smart enough to detect that this
is a comma delimited file and that the first
row contains header information. The only
things we have to tell it are the X and Y
fields for the coordinates.
Select LON for X Field and LAT for Y
Field (remember latitude is your angular
distance from the equator; Figure 14). Next,
select OK. The coordinate system selector
pops up. In our case, we will stick with the
WGS-84 coordinate system, which is selected
by default (Figure 15). Click OK again. We
are returned to the main window with all of
our flight path plotted as a series of dots.
By right-clicking on the file name in the
layers panel, you can access a variety of
36 SERVO 08.2017
Figure 15: The WGS-84 coordinate system is used for our data,
but feel free to explore the others and see how big of an offset
there is between the datums at your location.
Figure 16: The Properties window lets you modify the appearance of the scatter
points showing where data was collected.
Figure 13: The QGIS application: a great
piece of free and open source software that
can plot many types of geographic files and
make publication quality graphics.
Figure 14: The delimited text layer import tool is relatively
intelligent and makes good default selections for our file. Be sure to
set the X and Y coordinate variables.