slope aspect splitter :: Earth Volumetric Studio Help

slope aspect splitter

The slope aspect splitter module will split an input field into two output fields based upon the slope and/or aspect of the external face of the cell and the subset expression used. The input field is split into two fields: one for which all cell orientations are true for the subset expression, and another field for which all cell orientations are false for the subset expression.

All data from the original input is preserved in the output.

Flat Surface Aspect: If you have a flat surface then a realistic aspect cannot be generated. This field lets you set the value for those cells.

To output all upward facing surfaces: use the default subset expression of SLOPE < 89.9. If your object was a perfect sphere, this would give you most of the upper hemisphere. Since the equator would be at slope of 90 degrees and the bottom would be >90 degrees.

(Notice there is potential for rounding errors, use 89.9 instead of 90)

Note: If your ground surface is perfectly flat and you wanted only it, you could use SLOPE < 0.01, however in the real world where topography exists, it can be difficult if not impossible to extract the ground surface and not get some other bits of surfaces that also meet your criteria.

General expression (assuming a standard cubic building):

A) SLOPE > 0.01 (Removes the top of the building)

B) SLOPE > 0.01 and SLOPE < 179.9 (Removes the top and bottom of the building)

Since ASPECT is a variable it must be defined for each cell. In cells with a slope of 0 or 180 there would be no aspect without our defining it with the flat surface aspect field.
Units are always degrees. You could change them to radians if you want inside the expression. (SLOPE * PI/180)

Ports

Direction	Name	Type	Description
Input	Input Field	Field	Accepts a data field.
Input	Input Number Variable 1	Number	Accepts the first numeric value for the slope or aspect expression.
Input	Input Number Variable 2	Number	Accepts the second numeric value for the slope or aspect expression.
Input	Input Z Scale	Number	Inputs Z Scale (vertical exaggeration) from other modules.
Output	Output True Field	Field	Outputs the field which matches the subsetting expression.
Output	Output False Field	Field	Outputs the opposite of the true field.
Output	Output Z Scale	Number	Outputs Z Scale (vertical exaggeration) to other modules.

Properties

Property	Type	Description
Z Scale	Double	Z scale is the scaling factor used on the input field.
Flat Surface Aspect	Double	The value to use for Aspect Value over a flat surface.
N1	Double	The N1 variable usable by expressions.
N2	Double	The N2 variable usable by expressions.
Subset Expression	String	The expression used to subset the input field.
Subset Variables	String	Variables available for determining which field to write output.
Split Edges	Boolean	Split surfaces when the edge between two neighboring cells is sharp. This improves rendering in most cases.
Split Edge Angle	Double	The Split Edge Angle is the maximum angle allowed between two adjacent faces before they are disconnected to create visually sharp edges.