Feature Description

In the "Dot Density Thematic Map" window, users can modify various parameters of the dot density thematic map to achieve more customized visualization effects.

Steps

1. Select a dot density thematic map layer in Layer Manager, click the pop-up dialog button at the bottom-right corner of the "Dot Density" group. The "Dot Density Thematic Map" window will display current settings.
2. Thematic Map Layer: Shows the name of the current thematic map.
3. Expression: Displays and sets the thematic variable (either a single property field or mathematical expression) used to create the current map.
   • Click the drop-down button in the "Expression:" combo box to view all available property fields from the region dataset;
   • Select a thematic variable (single property field) from the list. Alternatively, choose "Expression..." to build field expressions in the "SQL Expression" dialog;
   • The map will automatically update using the modified thematic variable and refresh display effects.

   Note: For Oracle Plus/SQL Plus engine datasets, field expressions must be field values or arithmetic operations (e.g., SmID or SmID+1). Conditional expressions like "SmID > 100" are unsupported and will cause thematic map failure with "Thematic map update failed" in output window.

4. Value Per Dot: Determines the numerical value represented by each dot.
   • Enter a value manually or use spin buttons. Example: If set to 500,000, a region with 1,000,000 population will display 10 dots.
5. Dots for Max Value: Specifies the number of dots in regions with maximum thematic values to control density.
   • This value inversely correlates with "Value Per Dot". Adjusting either parameter automatically recalculates the other. Observe map effects to fine-tune values.
6. Point Style: Customizes the symbol style for all dots in the map.
   • Click the button next to "Point Style:" to open the "Point Symbol Style Settings" window.
7. Parameters in this window apply to the map in real-time (WYSIWYG). Uncheck "Enable Instant Refresh" at the bottom to disable auto-update. Click "Apply" to manually apply changes when auto-refresh is disabled.

Notes

1. Customized dot density thematic maps can be saved as templates for reuse. See: Save to Thematic Map Template Library.
2. When creating thematic maps via templates, select saved templates from the "Templates" dropdown menu.