2D Grids
Certain series (i.e. Color
Grid, Contour, Surface,
Triangle Surface, Tower, Water
Fall, and 3D Points) with three series
components - Position, Depth, and Value - require
that the data in the Position and Depth components form a special
two-dimensional grid, or 2D grid. For these series, the
2D grid must be built on the xz plane of the graph with the x
values and z values associated with the Position and Depth
series components, respectively.
The easiest way to
setup a 2D grid is to use the Setup 2D Grid sub menu on the Data
menu (which is also the context menu of the active data table
or data sequence). This sub menu contains two
menu commands: Rectangular
Grid and Circular Grid. Selecting either one opens the 2D
Rectangular/Circular Grid dialog box with which the corresponding 2D
grid can be set up on the active data table or the current data table of the
active data sequence.
Selecting the Rectangular
Grid menu command sets ups a 2D rectangular grid on two data-table
columns: one is used to contain the x values (the data in the Position
series component) and is called the X grid; the other is used to contain
the z values (the data in the Depth series component) and is called the
Z gird. Both grids are equally spaced. The start, end, and step
values of each grid can be customized with the 2D
Rectangular/Circular Grid dialog box. Color Grid,
Contour, Surface,
Tower, Water Fall, and 3D
Points use 2D rectangular grids.
Selecting the Circular Grid menu command sets ups a 2D circular grid on
two data-table columns. In a 2D circular grid, the grid points are equally
spaced in the two dimensions of the polar coordinate system:
the radial dimension (denoted as r) and the angular dimension (denoted
as q). The start, end, and step values of the
grid points in these two dimensions can be customized with the 2D
Rectangular/Circular Grid dialog box with the limitation that the start and end values of the
angular dimension are fixed to 0 and 2p
(360°),
respectively. The polar coordinates of the grid points are then transformed
into coordinates in the xz plane using the following formulas:
x = rcosq
(1)
z = rsinq
(2)
It is obvious that the grid points generated this way locate on a set of
equally spaced concentric circles about the origin of the xz plane.
Triangle Surface uses 2D circular grid.
See Also
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