User`s guide

ODV HowTo

The latitude/longitude coordinates of the coastline or depth contour are stored in indi-

vidual polygon segments (see Figure below). The first n

nodes of a segment represent a

part of the actual coastline or bathymetry contour. This part of the segment is stroked

when the outline of the contour is requested. In addition, each segment can have an op-

tional, second part which will not be stroked but is only used to properly close the seg-

ment. Segments that also contain this second part can be filled and/or stroked. The total

number n

of nodes in any segment must not exceed 1500. If a segment has no second

part, the number of stroke points n

must be equal to n

Figure 3-1: Schematic diagram of an ODV coastline/bathymetry segment.

Latitude/longitude coordinates are decimal values: longitude is in degrees East (0 –

360) and latitude is in degrees North (-90 – 90). A polygon segment in a .coa file is spec-

ified as follows:

lat

lon

.....

lat

lon

where n

is the total number of vertices for this segment and n

is the number of ”true”

coast/bathymetry vertices. n

may be larger than n

, in which case vertices n

+1 .... n

are used to close the segment (land-side closure). These extra vertices are not shown

when the segment is stroked. Note that both, n

and n

, must be smaller than 1500. On

the line following the last vertex of a segment, the next segment is started by specifying

its n

and n

values. There is no blank line between segments. To indicate the end of the

file put ”0 0” in the last line of the file. .coa files have to be converted to binary format

(.cdt files) before they can be used by ODV. A .coa to .cdt converter (coa2cdt.exe) is in-

cluded in the ODV distribution package for Windows. To use the coa2cdt converter do

the following: