Most Map Layers have a Map Key property that can be used to customize the appearance of the layer. When you create a new map in Overture, the map key is populated with default values, but you can easily change this is you wish. The customization options for map layers are very flexible, and allow you to easily generate a wide variety of different map styles.

You can access the a layer's map key from the properties of the map layer:

Map keys have the following properties:

• Color Value Definitions. This is the set of color/value pairs that controls the color scheme for a particular map.
• Map Coloring. This controls how the entries in the Color Value Definition list are interpreted. This property can take the following values:
  • InterpolatedHSLA. Colors for between-band values are interpolated in HSLA space. This gives smooth thermographic-style colorings for maps.
  • InterpolatedRGBA. Colors for between-band values are interpolated in RGBA space.
  • Banded. Colors for between-band values take on the color of the lower nearest band. This is useful if you want to produce maps based on a series of thresholds.
  • Unique. The set of Color Value Definitions are ignored, and a unique color is generated for each unique value in the source data. This is useful when the source data has few distinct values.
• Map Scale. This controls the scaling applied to the map values. It can be set to Logarithmic or Linear. Logarithmic scaling is recommended if you wish to exaggerate the differences between small values in the source data.
• Mark Unset Values. If set to True, then you can specify an unset value and an unset color.
• Unset Color. This is the color that will be applied to unset values. This is typically set to be Transparent, White or Black.
• Unset Value. This is the value to consider as being "Unset". If Mark Unset Values is True, this color will be used when drawing any point with a value equal to Unset Value.

You can edit the Color Value Definitions property by clicking on the ... button. This raises the Color Value Definitions editor:

Each entry in the list has a color and an associated value. The screen shot above is for the Signal Strength map, so the values are taken to be power values. The source data in this case is a map of signal values; the color/value definitions above tell the map what color to display for each possible signal level.

The actual color generated for a particular input signal level depends on the setting of the Map Coloring property. If this is set to InterpolatedHSLA or InterpolatedRGBA, the entries above and below the given value are found and a color is generated by interpolating the two colors for these entries. When the map coloring is set to Banded, the color of the smaller of the entries surrounding the given value is used. In all cases, if the value is outside the range of color/value definitions, then the color of the closest entry is used.

Clicking the Add button will add a new color/value entry into the list. You can also remove entries by selecting them in the list and then clicking the Remove button.