Travel Time Curves

Travel time curves can be added to a plot by specifying a note file containing primarily range-time pairs but also certain inline commands detailed below that control the interpretation of the range-time pairs and also the appearance of the travel time curves such as their thickness and color. By default all travel time curves are clipped to the bounds of the plot. This means the travel time curves can be broken into individual lines by including a pair of points which would plot outside the bounds of the plot. In addition the number pair 99.999 99.999 is always interpreted as a line separator.

ntfile (s) - Note file. The name of the file containing the x-t pairs that should be plotted plus any inline commands. Multiple travel time files may be plotted by defining additional plot-end$ pairs.

Inline Commands

The inline commands consist of a string by itself on one line specifying the command. Some of the inline commands are followed by a second line containing arguments to the command.

xtp
Specifies that the number pairs defining the travel curves are interpreted as the plot range and time. This is the default interpretation.

offset
The range element of each number pair is interpreted as the source-receiver offset.

ktp
The first element of each number pair is interpreted as a defining a sort key value. For example, RP number in a stacked section. Since only one sort key value is defined in the ntfile, this method only works if one of the two sort keys for the plot fixed. This is typically the case for plotting stacked sections, CMP gathers or shot gathers. Pltsegy will check each sort key and will interpret the sort key value as referring to the one that varies. So in the case of a stacked section the sort key value will be taken as referring to the RP number, but in the case of a gather it will refer to the trace number. The key value must appear in the traces selected for plotting, so that pltsegy can look up the appropriate plot range for the point on the travel time curve. Any key value not found is quietly dropped from the curve.

dash
<dash1> <space1> [<dash2>, <space2>]
Dash specifies the length of the dashes and spaces for a dashed line. Lengths are in mm. Two dash-space pairs may be specified allowing long-short dash lines to be produced. A value of 0 0 0 0 produces a solid line. (Default = 0 0 0 0)

thick
<thickness>
The thickness of the line is specified in pixel units. Thus the line thickness is device resolution dependent and a large thickness is usually required for laser printer output. The algorithm uses a simple vertical stacking approach which means that the thickness of the line does not increase very rapidly if it lies at a large angle to the horizontal.

color
<color>
Define the line plotting color. Any colors available in "rgb.data" are available as line colors.

offclip
Turn off clipping by the bounds of the plot frame. By default all travel time curves are clipped to the plot boundaries. This does not allow, for example, a travel time key to be produce outside the plot with or without an enclosing box.

onclip
Turn clipping at the plot frame back on