2D Region definition file format

This section describes the format of the file that is created when you export 2D region definitions. These files have an .evr file extension and are referred to as EVR files. 3D regions cannot be exported to files of this format.

You can analyze EVR files using any external software that can read text data files. You can also modify EVR files using external software and re-import them into Echoview. If you create or modify EVR files you should do so carefully as Echoview may crash or exhibit other problems on encountering a file that it considers corrupt.

Overall structure

Region definition files are structured text data files. A CR/LF pair terminates each line (this is the DOS convention, not the UNIX convention that uses a single LF to terminate each line).

An EVR file consists of the following parts:

A single line containing the string "EVRG", followed by the EVR file format version number (currently "6"), and the version number of Echoview that created the file. Each of these three fields is separated by a single space. For example:

"EVRG 6 3.00.41"

This line is followed by a single line that contains the number of regions in the file, e.g.:

"2"

This line is followed by the data for region 1, the data for region 2, and so on. The data structure for a single region is described in the next section.

Structure corresponding to a single region

A number of fields are written for each region. Each of these is followed by the separator listed in the following table.

Field	Separator	Description
Blank line	CR/LF	Region separator
Region structure version	Space	"13" (will be incremented if the region structure changes in future versions)
Point count	Space	Number of points in the region
Region id	Space	Unique number for each region. Specify sequential numbers starting at 1 if creating a new file
Selected	Space	"0" (always)
Region creation type	Space	See Data formats below
Dummy	Space	Should always be "-1"
Bounding rectangle calculated	Space	"1" if the next four fields are valid "0" otherwise
Left x value of bounding rectangle	Space	Date and time of left boundary of bounding rectangle – ignored on input when importing into Echoview.
Top y value of bounding rectangle	Space	Upper depth coordinate of bounding rectangle – ignored on input when importing into Echoview.
Right x value of bounding rectangle	Space	Date and time of right boundary of bounding rectangle – ignored on input when importing into Echoview.
Bottom y value of bounding rectangle	CR/LF	Lower depth coordinate of bounding rectangle – ignored on input when importing into Echoview.
Number of lines of notes	CR/LF	The number of lines of region notes to follow.
Region notes	CR/LF	Notes associated with the region. Maximum length is 2048 characters. Embedded CR characters are encoded as hexadecimal FF. Embedded LF characters are encoded as hexadecimal FE.
Number of lines of detection settings	CR/LF	The number of lines of detection settings to follow.
Region detection settings	CR/LF	The detection settings as defined in the Fish Track Detection Properties dialog box or Detect Schools dialog box.
Region classification	CR/LF	Region classification (string). Default value is "Unclassified"
Point 1	Space	Data for first point – See Data formats below. These data are used to bound the region when importing into Echoview.
...	Space	...
Point N	Space	Data for last point – See Data formats below.
Region type	CR/LF	"0" = bad; "1" = analysis; "2" = marker
Region name	CR/LF	String

Data formats

The region creation type is one of the following:

Region creation type	Description
-1	No type
0	Created from a selection made using the horizontal band tool
1	Created from a selection made using the parallelogram tool
2	Created from a selection made using the polygon tool
3	Created from a selection made using the rectangle tool
4	Created from a selection made using the vertical band tool
5	Created as a bottom-relative region or line-relative region
6	Treated as 7
7	Created using the Detect Schools command
8	Invalid or unknown region type
9	Created as a fish track region

Dates are encoded in CCYYMMDD format, times in HHmmSSssss format, where:

CC	=	century	e.g.	20
YY	=	year	e.g.	03
MM	=	month	e.g.	01
DD	=	day	e.g.	07
HH	=	hour	e.g.	14
mm	=	minute	e.g.	23
SS	=	second	e.g.	13
hh	=	hundredths of a second	e.g.	87
ssss	=	0.1 milliseconds	e.g.	2854

Depths are written in meters in decimal notation.

Point data

The data for a single point is encoded as a date, a time, and a depth separated by spaces.

Note: Self-crossing regions are not supported. That is, the line which defines the boundary of the region may not cross itself.

Example file

This file contains 5 regions: a bad data and a marker region, and 3 analysis regions. Regions 1-3 were created with the rectangle tool, Region 4 with the horizontal band tool, and Region 5 is a schools detection.