WinDisp Circle Posting Menu

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WinDisp Circle Posting Menu

Circle Posting

This option produces a circle of fixed radius with a sector for each data value with each sector being filled in proportion to the data value assigned to the sector. When Circle posting is selected the Data Posting Specification menu has the following form:

This menu display contains a number of standard items which are displayed for all menu styles and a number of items which are specific to the particular posting style.

General Posting Options

Circle Specific Specifications

With circle posting up to sixteen data values can be selected. These data values are chosen from the available data items by clicking in the grid cell under the column heading Name of Data Variable in the preferred row in the data definition grid. These rows do not need to be defined contiguously, and any valid row will be posted on the display. Clicking in any cell in the Name of Data variable column brings up a drop down box from which the desired data variable can be chosen.

Maximum Radius

With circle plotting, all data values are plotted within a circle of fixed radius which is specified by this value.

Display Data Range button

Once the coordinates and required data variables have been defined, the user can check the range of data values contained in the file by clicking on the Display Data Range button. Clicking on this button brings up the Data Range Menu. When this button is clicked for the first time, the currently selected data variables are read from the file and stored in a temporary binary file to speed future access to the data. This temporary file will be retained for the current WinDisp session or until it becomes invalid through a change to the data variables chosen or the line variable, so it is recommended that all data of interest are selected on first entering the Data Specification menu.

Define Data Variable

After specifying the coordinates and required data variables and the area limits and map scale, the parameters determining how the individual data values will be posted need to be specified. This is achieved by clicking on the Define Data Variable button. This will bring up the parameters for the currently selected line in the data definition grid, or the first variable specified in the grid if there is no currently valid selection. Clicking on the Define Data Variable button brings up the following form:

Data Variable

This displays the user name of the currently selected data variable.

Minimum Value

This value specifies the minimum value for which the data marker will be displayed. If the data value is less than the minimum the sector assigned to this data value will be left empty. This value must be smaller than the maximum value.

Maximum Value

This value specifies the largest value which is to be used for displaying the data marker. If the data value is larger than the maximum value it is simply truncated to the maximum value. This value must be larger than the minimum value. The proportion of the sector filled is computed using the following formula:

ratio = ( value - minimum ) / ( maximum - minimum )

when log scaling is no selected, and

ratio = log ( value / minimum ) / log ( maximum / minimum )

for log scaled posting.

Null Value

This text box displays the null data value for the current data variable, this value is provided for information only and the null data value should be changed on the Specify Data Names menu

Logarithmic Scaling

This check box specifies if the log (base 10) of the data value should be used in posting the data.

Number of Decimals

This integer value specifies the number of digits after the decimal point to be used in displaying numeric data values in text format.

Label Rotation

This value specifies the rotation to be applied to the currently selected data variable and is measured in degrees positive counter clockwise about the centre of the label position. This rotation is applied after any posting rotation specified on the main Posting Specification menu.

Fill Style

This index specifies the type of fill to be applied to the sector for the currently selected data variable. A value of -1 indicates that no fill pattern should be used, a value of zero indicates that a solid fill, and values greater than 1 select various type of hatching fill patterns.

Fill Colour

This box displays the pen colour which will be used to display the perimeter and interior fill for the currently selected sector. In addition if the sector radius is larger than the specified maximum radius the data value will be posted using this pen colour. If the colour needs to be changed, click on the colour box to bring up the Pen Colour Specification Menu.

Posting Preview Window

In the lower part of the Post Variable Definition menu is the Posting Preview Window. If the current display area limits and map scale are defined and valid, this window displays the currently defined posting style. As the posting specifications are changed, the suitability of the choices for the parameters can be checked by clicking on the Redraw and the Next and Previous buttons. The x, y and data values are also displayed in the text boxes on the right of the preview window.

Selected Data Variable Drop-down Box

At the bottom left hand corner of this form is a drop-down box containing a list of all data variables currently specified in the data definition grid. By selecting each of the data variables in this list, the parameters defining the posting of each data variable may be specified without returning to the main form.

Finally the Display Data Range menu is accessible from this menu by clicking on the Display Data Range button at the bottom of the screen.

Any changes made from the menu can be discarded by clicking on the Cancel button, otherwise the changes will be saved if the OK button is clicked.