CD-Sextant - Build your own sextant - Pole Shift Survival Information

Navigator Light Software
Navigator uses a custom chart file format, with the CHT extension. These are plain text ASCII files and can be edited with
the Windows Notepad or Wordpad. Because providing detailed vector charts of all regions of the Earth is a demanding task,
I choose to give users a tool to roll their own charts. Producing a vector chart means using a raster chart image to digitalize
the points in the shoreline.
Chartmaker accepts three image formats: Windows BMP, GIF and JPG. If you are scanning paper charts, JPG is probably
the best format, because files are smaller. It's a compressed format.
The CHT file
Once you have the image of the chart, load it in Chartmaker. Now you have to define the scale for this chart. Click and enter
the Earth Coordinates for three distinct reference points of the image, as described above.
1. Choose three points that are relatively distant to each other (at least 1/3 of the screen). Select points that form a right
angle. Click the points and enter their Earth coordinates.
2. After the third point, the caption will show the coordinates of the cursor, as you move the mouse. Check the
coordinates of other points, to certify that your scale is accurate.
3. Select "Edit, Draw Axis" in the menu. The program will draw vertical and horizontal axis in 30' intervals. Check if
they are the same as the image's axis. Draw again to erase the axis.
4. Now draw the shoreline, clicking the points with the mouse. Draw different polygons to represent the islands and
continents.
5. After clicking all points of a given polygon, press the "close polygon" button. The last point will be connected to the
first. All polygons must be closed.
6. Give a name for the polygon.
7. After drawing all the polygons, save the CHT file.
8. Open it in Navigator chart viewer, to see the result. Zoom in and out, to check the details.
In the figure to the left, the 3 reference
points are marked 1, 2 and 3. The
coordinates are:
1) 24°00.0S 46°25.0W
2) 23°50.0S 46°25.0W
3) 24°00.0S 46°06.6W
If you open the supplied myworld.cht
file in Navigator, you will see a
simplified chart of the whole world. I
made it more detailed in one part
(44°00'W 23°30'S), the region I usually
navigate. You can do this for your
region, by directly editing the CHT file
with a text editor and adding the
polygons of your region. This is a little
tricky. You might prefer to roll a chart
of your region only.
You may also merge CHT files, using an ASCII text editor (like the Notepad or Wordpad). Take a look in the CHT file
header for more technical details on the CHT file format.
xxx
http://www.tecepe.com.br/nav/navpro.htm (22 of 23) [9/2/2004 11:05:07 PM]