• Introduction
• The Utility of Maps
• Producing Displays
• Point Symbolization
• Line Symbolization
• Choropleth Symbolization
• Graduated Symbol
• Grid Symbolization
• Dot Density Symbolization
• Isopleth Symbolization
  • Monovariate
  • Bivariate Monochrome
  • Bivariate Color
  • Multivariate
• Thematic Mapping
• References
• Index
• Author Index
• Symbol Index
• Site Map

Bivariate Color Symbolization

Monochrome, bivariate fishnet maps can be generated by value shading a surface. Like monochrome, color bivariate isolines can be created by changing the current line's color and drawing a second isoline coverage. Color, bivariate fishnets can be generated by hue shading a surface.

Ratio Data and Nominal Data--Surface Shaded with Hue

Figure 9.2a: SFH.aml Continuous, smoothly changing ratio data displayed as a surface. The surface is hue shaded with a nominal dat set (the AML supports polygons and grids).

A prime example of the appropriate use of hue shaded surfaces is the display of land use/land cover data over a digital terrain model. Although this is a common use, hue can be used for any nominal data (this AML supports both choropleth and grid cell data). The surface can be any continuous, smoothly changing ratio data set. See SFH.aml and Figure 9.2a.

SFH <surface> <hue_lookup> {zfactor} {lattice|tin} {resolution} {value} {intensity}

<surface>

a grid layer or TIN

<hue_lookup>

specifies HLS hue (from 0 to 300)

{zfactor}

`Z' expansion factor--defaults to z-range / the larger of x-range and y-range

{lattice|tin}

the type of <surface>--defaults to lattice

{resolution}

the density of fishnet lines--defaults to the smaller of x-range and y-range / 25

{value} {intensity}

defaults to 50 and 100 (maximum intensity);.