Vis5D Documentation
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# Slices

Slices allow you to look at planar cross sections of data in the 3-D box. These slices can be oriented either horizontally or vertically and may depict either contour lines, colored slices, wind vectors, or wind stream lines.

As described in section 6.2, the last group of buttons on the control panel is a matrix of buttons, the second through fifth columns of which control slices. There is a column of buttons for horizontal contour slices, vertical contour slices, horizontal colored slices and vertical colored slices, respectively. If your data set contains U, V, and W variables, there will also be a row of wind vector slice buttons as described in 6.2. There are two buttons for horizontal wind slices and two buttons for vertical wind slices.

To activate/turn on a slice, click on the appropriate widget button with the left mouse button. The initial position for slices is the middle of the box. The exact slice location in terms of latitude, longitude or elevation is given by a small numeric labels near the one corner of each slice. To print the numbers as grid coordinates instead of geographic coordinates, toggle the "GRID #s" widget button on the control panel.

The position of slices can be changed interactively using the mouse. To do so you must first be in SLICE mode by selecting the SLICE radio button. To move any slice, simply point at the slice's corner with the mouse, press the right mouse button and drag it to a new position. Vertical slices may also be moved in a perpendicular motion by "grabbing" the middle of the top or bottom edge and dragging it. A slice may be moved while in animation mode, however, some jumpiness may occur because new slices are computed asynchronously.

Slices may also be linked in a chain. When slices are linked, the state and movement of all the linked slices are synchronized. Horizontal and vertical slices can not be linked. Slices can be linked by using the API function call 'vis5d_link_slices' and 'vis5d_unlink_slice' from a script or via the 'INTERP' button in the control panel.

## Contour Line Slices

When viewing a horizontal or vertical contour line slice (button columns two and three) a small control window will appear as well. In this pop-up window you can enter the interval to use between contour lines. Just type in a new number to change the interval. Decreasing the interval will cause denser contour lines to be generated, increasing the interval will result in sparser lines.

If you enter a negative interval then all contour lines with a negative value will be drawn with dashed lines while positive values will be drawn with solid lines.

Optionally, after the interval value you may specify a range of values (a,b) which will cause only contour values between a and b to be drawn. For example, suppose you enter

-10 (-30,20)

This will result in contour lines for values between -30 and 20 at intervals of 10 with negative lines drawn as dashed lines.

The "CONT #s" button on the control panel toggles the display of the contour numbers within the slice.

The SFC button will cause the horizontal slice data to be sampled from the topography surface then displayed on top of the topograhpy.

## Colored Slices

When a viewing a horizontal or vertical colored slice (button columns four and five) a color table window will appear. In this pop-up window you can change the mapping from data values to colors. If the LEGENDS control panel button is selected the color table will also be displayed in the 3-D viewing window.

The window shows graphs of red, green, and blue over the range of data values. To change the red, green, or blue function press the left, middle, or right mouse button, respectively, and drag the mouse to draw a new function. By default, low data values are mapped to blue and high data values are mapped to red.

Instead of using the mouse you can use the keyboard cursor (arrow) keys to modify the shape and position of the default function curves. Press the left/right keys to move the curves left or right. Press the up/down keys to change the shape of the curves.

You may also change the transparency of the slice as a function of the data values. Press and hold the SHIFT key while using the mouse or up/down keys to change the transparency.

There are a number of other keyboard controls for the color table window:

r | reset red, green and blue values
R | reset transparency values
c | copy color to an off-screen clipboard
p | paste colors from the off-screen clipboard
s | save color values to a file, enter filename in your shell window
l | load color values from a file, enter filename in your shell window

## Wind Vector Slices

Wind vector slices are displayed with the buttons near the center of the control panel labeled HWIND-1, VWIND-1, HWIND-2 and VWIND-2. The pop-up window for these graphics contains two type-in fields to control the density and scaling of the wind vectors. The scale parameter is used to multiply the length of vectors drawn. If you want to double the length of all vectors, enter 2.0. If you want to halve the lengths, enter 0.5. The density parameter controls how many wind vectors are displayed. This value can only be between zero and one. To make one-half the number of vectors, enter 0.5, for one-fourth enter 0.25, etc. The default values for both parameters is 1.0.

The SFC button for horizontal wind slices will cause the slice data to be sampled from the topography surface then displayed on top of the topograhpy.

## Wind Stream Slices

Wind stream slices show the path of wind as connected line segments. The pop-up control window contains a type-in widget to control the density of streamlines (note that the scale parameter is not used). The density parameter controls how many streamlines are displayed. This value can only be between 0.5 and 2.0. To make one-half the number of streamlines, enter 0.5, to make twice the number of streamlines, enter 2.0, etc. The default density is 1.0.

The SFC button will cause the horizontal slice data to be sampled from the topography surface then displayed on top of the topograhpy.

## Slice colors

The color of a slice's control button matches that of the slice itself (except for colored slices for which the slice's tick mark matches the slice's button.) To change the color of a slice click on the slice's button with the right mouse button. A window with red, green, and blue sliders will appear. Move the sliders to change the color.

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