Batch Depression Contour

Vr Mapping

ON-LINE REFERENCE DOCUMENTATION

CARDINAL SYSTEMS, LLC

www.cardinalsystems.net

Batch Depression Contours is used to change the graphics pointer (i.e. line style) of depression contours.

Key-in	Description	Range
PARFIL=	Load parameter file	Batch Depression Contours parameter file name (.btt)
RUN	Run Batch Node

Defines the layers containing the contours lines to be flagged. A number line may be used to define the layers.

Defines the graphics pointer to assign to depression contours. 10 is the default and produces tick marks that point downhill.

Defines the maximum area that contours may contain in order to be considered for depression flagging. If this number is 0 then it will be ignored. This option is useful if all contours are being flagged (not just bottom contours).

Choose the definition of a depression contour that meets you needs. We have not been able to get our customer base to agree on definition of depression contour. Hence, the key processing parameter is a choice among the definitions. If you don't find a definition that meets you needs contact support@cardinalsystems.net to request a custom definition. Each of the definitions is described and presented with an example. The example data that will be used is shown below. In the left top is a straight forward pit and mound. In the bottom left is feature with elevation direction changes. On the right is settlement pond surrounded by a low berm. The surface inside the settlement pond alternates above and below the 100' contour.

Definition 1: A depression contour is "a closed contour that would hold water inside it"

This is the most straight forward definition, and the results are shown below. Notice:

•	Not all the contours in the pond on the right are depression contours because the surface is most probably alternating above and below the 100' level.

•	The large 100' contour in the bottom left is a depression contour even though there is some area inside it that is higher--there is still some area that would hold water.

•	The smaller 80' contour in the lower left is not a depression contour because it is most probably a slight rise at the bottom of that hole.

Definition 2: A depression contour is "a closed contour inside a higher closed contour"

This definition makes any contour that is inside a higher closed contour a depression contour. Using this definition, the inside of a depression contour might not hold water. See the results below, note that

•	All the contours in the pond are depression contours, but the tick marks alternate directions to show the downhill direction.

•	The large 100' contour in the bottom left is not a depression contour because it is not inside a larger contour.

•	The smaller 80' contour in the lower now a depression contour and the tick mark directions indicate that it is most probably a slight rise at the bottom of that hole.

This definition is admittedly an abuse of the term 'depression contour', but it was requested. When used with graphic pointer (line style) 10 it marks closed contours with ticks that point downhill. See the example below, Note:

Definition 4: A depression contour is "the lowest closed contour that would hold water"

Using this definition contours on the way down are not marked; only the bottom contour is marked. See the example below. Note:

•	In the top right there are two 'bottom' contours one inside the other. This is because the ground rises some between alternating 100' contours, and hence there are two separate 'depressions' in that basin.

•	Only the larger 80' contour in the lower left marked a depression because the ground has most probably started to rise and the other 80' contour marks the boundary of a somewhat higher area.

This is an alternative way to view contours at the bottom of a basin. All of the lowest contours are marked as depression contours. See example below. Note:

Definition 5: A depression contour is "the lowest empty closed contour that would hold water"

Using this definition a contour must not only hold water it must also be the lowest contour in a basin and contain no other contours (higher, lower, or equal elevation). See example below. Note:

•	The bottom left basin has no depression contour. This is because the inside contour does not hold water (it is most probably a slight rise at the bottom of the sink).