This design places samples along contours of a suspected plume. It provides a page of settings for matching the contours of an idealized plume and a page for placing samples on those contours. When applied it will create a sample area to contain the samples and place contour lines on the map.
This page provides the following control settings designed to match an idealized plume:
Size X
The radius of the inner contour perpendicular to the upgradient / downgradient direction (see figure below)
Size Y
The radius of the inner contours parallel to the upgradient / downgradient direction (see figure below)
Shift
Specifies an amount (0 - 1) of the upgradient portion to be shifted towards the downgradient portion of the contour. The figure below shows the effect of different shift amounts.
Contours
The number of contours (1 - 10).
Angle
Specifies the angle in degrees (0 - 359) from the center to the downgradient direction. An angle of zero means the downgradient will be towards the bottom of the map. An angle of 90 means that the downgradient will be to the right side of the map.
Step Up
This is the distance between the 1st and 2nd contours in the upgradient direction. This distance is before the shift or multiplier is applied. See figure below.
Step Down
This is the distance between the 1st and 2nd contours in the downgradient direction. This distance is before the shift or multiplier is applied. See figure below.
Step Side
This is the distance between the 1st and 2nd contours in the direction perpendicular to the upgradient / downgradient direction. See figure below.
Mult Up
This is the multiplier in the upgradient direction. This multiplier specifies how much to change the spacing between subsequent contours. A multiplier of 1 means that each contour will be spaced the same as the previous contour. A multiplier of 2 means each contour will be spaced twice as far as the previous transect. A multiplier of 0.5 means each contour will be spaced half as far as the previous transect.
Mult Down
This is the multiplier in the downgradient direction. This multiplier specifies how much to change the spacing between subsequent contours. A multiplier of 1 means that each contour will be spaced the same as the previous contour. A multiplier of 2 means each contour will be spaced twice as far as the previous transect. A multiplier of 0.5 means each contour will be spaced half as far as the previous transect.
Mult Side
This is the multiplier in the direction perpendicular to upgradient / downgradient. This multiplier specifies how much to change the spacing between subsequent contours. A multiplier of 1 means that each contour will be spaced the same as the previous contour. A multiplier of 2 means each contour will be spaced twice as far as the previous transect. A multiplier of 0.5 means each contour will be spaced half as far as the previous transect.
X Coord
This specifies the X coordinate of the center of the contours. The center of the contours can also be set by pressing the Pick Center button and clicking on the map.
Y Coord
This specifies the Y coordinate of the center of the contours. The center of the contours can also be set by pressing the Pick Center button and clicking on the map.
Pick Center
Pressing this button then clicking on the map allows you to interactively set the center point of the contours.
This page provides the following control settings that specify how the samples will be placed on the contours (not all controls will be visible on the screen at the same time):
Select one of these three main sample placement approaches:
Equal number of samples on each contour
Equal spacing (approximately) along all contours
Functional spacing
This method places the same number of samples on each contour. You can specify the number to be placed on each contour, or you can specify the total number for the all the contours. Note: If entering a total number, VSP may round the number down to create an equal number on each contour. The samples can be equally-spaced along each contour or can be random within each equal-length segment.
When using equally-spaced samples along the contour, there are 3 options for aligning the samples between contours as depicted in this figure:
When using random samples within each equal-length segment, the contours are divided into equal-length segment and one sample is placed randomly within the segment. The result is that the samples are not evenly spaced, but are fairly spread out along the contour as depicted in this figure:
This method tries to make the spacing between samples the same on every contour. You can specify the approximate spacing length or the total number of samples. The three options for aligning samples between contours are the same as those depicted above for the equally-spaced samples.
This method allows you to specify the total number of samples to place. The combined effects of three factors determine how those samples are placed on the contours:
Distance Factor
The distance factor can range from -1 to 1, with zero being neutral. A strong negative value pushes samples away from the center of the contours and a strong positive value brings more samples closer to the center of the contours, as illustrated in the figure below:
Angle Factor
The angle factor can range from -1 to 1, with zero being neutral. A strong negative value pushes more samples to the upgradient direction and a strong positive value pushes more samples to the downgradient direction, as illustrated in the figure below:
Jitter
The jitter can range from 0 (with no effect) to 1 (with maximum effect). Jitter is the randomness that is applied to individual sample locations, as illustrated in the figure below:
