Visualisation Styles

Details

Last Updated on Wednesday, 02 January 2013 14:31

Introduction

The GeoDMS contains a fast and flexible map view component for visualising both raster data and vector data (points, arcs and polygon features). Two dimensional raster data are typically used in National or European land use modelling, such as the Ruimtescanner or the EU Clue Scanner. Vector data is used to model objects as points, arcs, polygons and networks, especially for local applications such as the WoonZorgWelzijn Verkenner. In order to visualise a data item in a map view, its domain unit needs to be a Geographic domain unit.

Visualisation is determined by various configurable aspects. Some aspects are only relevant for some feature types:

• size/width: size of symbols or width of arcs/outlines
• color: color of grid cells, point symbols, arcs, outlines and the fill color of poygons.
• hedging: for the interior of polygons
• font type: the font used for the point symbols and labels
• font character: the font character used for the point symbols and labels.

If no styles are configured, default style values are used. These default styles can be overruled by configuring the values in the configuration. The color styles can also be adapted with the GeoDMS GUI.

Configuration of Visualisation Styles

Visualisation styles are configured as data items with a DialogType property indicating the style type. For parameters, the values for the visualisation styles are configured as expression values (so they can be modified within the expression dialog in GeoDMS GUI). These items are configured in two ways:

1. As subitem of the values unit of the item to be visualised. Example:

unit<string> vrz_lbl: DialogType = "LabelText"
{
   parameter<float32> LabelSize
   :  DialogType = "LabelSize"
   ,  expr       = "value(8, fontsize)";
}

In this example a values unit for text labels is configured with as subitem a parameter for the fontsize. The DialogType for the values unit is set to "LabelText" to indicate the values unit is used for labels in the map. The subitem parameter has a DialogType = "LabelSize" configured to inform the GeoDMS that attributes with this values unit need to be drawn with a font size of 8 pixels. The name of the subitem parameter is irrelevant but for transparancy reasons it is advised to use a clear name like the name of the DialogType, as in the example.

In case the values unit is a class unit (a unit used for classifying/classified data), the visualisation style item can be part of the classification scheme. This item can be an attribute with the number of entries of the class unit, or a parameter with one value for all classes.

Visualisation styles configured for values units apply to all data items configured with these values units.

2. For each data item, the visualisation styles can be overruled by configuring a subitem for the data item with the requested visualisation style. If a visualisation style is configured as subitem of the geographic domain unit and this style is not configured for the values unit or within the classification used for this item, the style will be applied for the other data items of the same domain unit. Example:

attribute<point_rd> lokatie: expr = 
   "point(PresYCoord, PresXCoord, point_rd)"
{
   parameter<uint32>  SymbolColor
   :   DialogType = "SymbolColor"
   ,   expr       = "rgb(255,0,0)";
   parameter<float32> SymbolSize  
   :   DialogType = "SymbolSize"
   ,   expr       = "float32(8)";
}

In this example, two subitems are configured to set the color and size for symbols. In the next paragrahps different style items are described for point, arc, polygon layers and for labels in the map.

For grid data only the visualisation style for color, called BrushColor (see also polygon data ) item is relevant.