Entering an annotation
To enter an annotation
at the current location of the target
, just hit the space bar or choose
Item →
Add Annotation
and fill in the appropriate information when the Annotation Window pops up.
Another method of entering an annotation is to right click, with the mouse, on the image where you
would like to place the annotation and enter your text.
Viewing annotations
View annotations by left-clicking on the green cross-hair. DiveBase automatically saves text
annotations in a file with the extension “txt”. This will create an annotation file with the same name as
the “.shr” file but with ANN added to the name. Example: spruance.shr will have a spruanceANN.txt
for annotations. Image annotations are saved as .jpg image files.
Chart Overlay and Chart Registration
DiveBase Seafloor lets you navigate or track a target against the background of a chart. This could
be a nautical chart, but also a sidescan sonar plot or perhaps an engineering map showing pipelines
owned by an oil company. In either case, you start with a .BMP image. The chart registration
process defines the scale of the image, as well as its location on the surface of the earth as
expressed in UTM coordinates (see below).
These are two different subjects that relate to each other. Chart Overlay is just having the function to
have a mapped area in DiveBase SeaFloor. Chart Registration is software that comes with
DiveBase SeaFloor allowing you to register the chart (map image) to later use in SeaFloor.
Here are the steps to follow when using the Chart Registration software. First pull up and run the
software, which you can find in the same location as DiveBase SeaFloor.
Step 1:
Select
File—Start
Single Image Wizard
and a window will pop up walking you through the process of registering an
image (
Step 2 & 3
). A key note that you will want to remember while using this wizard is that it uses
UTM coordinates, not latitude/longitude. The Universal Transversal Mercator (UTM) system divides
the world into UTM grid squares and then specifies the location of any point within that grid as an
offset in meters north (northing) and east (easting) of the southwest corner of the grid square. UTM
is commonly used by surveyors, and virtually all GPS receivers can be configured to operate in
UTM. Latitudes and longitudes can be converted to UTM using free web calculators, if UTM
coordinates are not directly available.
To register an image for use as a chart, you will be asked for two points to reference. So you will
need the coordinates of two separate points. The better precision that you can achieve with these
points, the better the overall accuracy will be. For example, if you use a hand-held GPS device to
find the location of the two reference points, but the GPS has an error of 10 Meters then your overall
error will be worse. You do not want your reference points to be on the same x or y axis.
