Split on Changes in Direction

Use the Split on Changes in Direction option, (geogxnet.dll(Geosoft.GX.Database.SplitLinesByDirection;Run)*), from the Database Tools > Line Tools menu, to split your database lines when the line heading changes, regardless of the line direction.

The option is also available with the Gravity and Terrain Correction extension under the Moving Platform Gravity > Split Line menu.

Split on Changes in Direction dialog options

Maximum angular change

Split the line if the angular change in direction exceeds this value over a specified distance (next parameter). The angular change is a positive value limited to ≤45° , beyond which line segments will be deviating too much from a straight line.

Script Parameters: SPLIT_LINES_BY_DIRECTION.MAXIMUM_ANGULAR_CHANGE

Over a distance of

Specify over what distance, in ground units, the maximum angular change must occur, or be exceeded, for the line to be split. It is recommended to set this distance to twice the average line spacing.

Script Parameters: SPLIT_LINES_BY_DIRECTION.ANGULAR_CHANGE_DISTANCE

Break at XY separations

If you would like to further split the lines, when the gap between 2 consecutive points along a line exceeds a certain distance, enter it here. This value cannot be less than the above distance. If left blank this condition is not tested.

Script Parameters: SPLIT_LINES_BY_DIRECTION.XY_SEPARATION_BREAK_DISTANCE

Minimum line length

If the conditions above split the line to segments shorter than this length, the line is not split. This is to avoid a multitude of short segments approaching a big turn-around loop.

The default is 2.5 times the “Over a distance of” parameter.

Script Parameters: SPLIT_LINES_BY_DIRECTION.MINIMUM_LINE_LENGTH

Save discarded segments

To maintain the totality of the data after splitting the lines, select this option. If selected, the turn-around segments are saved as Special lines and prefixed with the term Disc. The discarded lines are numbered in the same fashion as the split survey lines.

Script Parameters: SPLIT_LINES_BY_DIRECTION.SAVE_DISCARDED_SEGMENTS

Lines to break

Select the line(s) to break. Options are: All lines, Currently displayed line and Selected lines.

Script Parameters: SPLIT_LINES_BY_DIRECTION.LINE- "A" : All lines, "S": Selected lines (default), "D" : Displayed line

Line number syntax

For the naming convention of the newly generated lines, you have three options.

X or Y position: In the attempt to generate unique line numbers, this option determines which major axis the line direction is closer to, and assigns the line numbers to be the first point ‘s X value if the line is along the general Y direction, or to the first point’s Y value if the line is along the general X direction. This option is desirable if the lines are close to a major axis, but may produce cumbersome long values otherwise.

Versions of original line number: Use this option if you intend to break the occasional line and preserve its number, either because you want to honour gaps along a line with minimal disruption or keep the major digits of the line number for grouping purposes. With this option, the split lines will all have the same number with incremented version numbers.

Sequential: Regardless of the direction or grouping, you can set a systematic line naming convention with equally incremented numbers. In this case, you will be prompted to provide the First Line number and the Line Increment. These two entries are only enabled by the Sequential option.

Script Parameters: SPLIT_LINES_BY_DIRECTION.OUTPUT - "1" : X or Y position (default), "2" : Sequential, "3" : Versions of original line number

Maintain line type

By default, the output lines will be of the same type as the input line they have been produced from. Each set of line types will start at the provided sequential start number. However, you can opt to create all the output lines of the same type (Line).

Script Parameters: SPLIT_LINES_BY_DIRECTION.MAINTAIN_LINE_TYPE – 1: Maintain line type (default), 0: All output lines will be of type line

First line

Specify the sequential number for the first split line.

Script Parameters: SPLIT_LINES_BY_DIRECTION.FIRST_LINE (default=10)

Line increment

Specify the sequential line increment for each split line.

Script Parameters: SPLIT_LINES_BY_DIRECTION.LINE_INCREMENT (default=10)

Reset fiducial start value to zero

Select this check box to reset your fiducial start values to zero. After splitting the line, the fiducial of the first point can be preserved (default) or set to zero .

Script Parameters: SPLIT_LINES_BY_DIRECTION.RESET_FID_STARTS [0-No, 1-Yes]

Application Notes

*The GX.NET tools are embedded in the geogxnet.dll file located in the "...\Geosoft\Desktop Applications \bin" folder. If running this GX interactively, bypassing the menu, first change the folder to point to the "bin" directory, then supply the GX.NET tool in the specified format. See the topic Run GX for more details on running a GX.NET interactively.