Map Creation and Visualization
Core concepts
A map displays layers from a shared coordinate system; a layout arranges map frames, legends, and text for printing or export. Know the difference between a map frame and a map, and between symbology types (single symbol, unique values, graduated colors, graduated symbols, proportional symbols, charts). Understand labeling (dynamic text placed by rules) versus annotation (stored features). Grasp scale concepts: scale-dependent visibility, reference scales, and why a layer may disappear when zoomed out.
Traps to watch for
- Changing a map's spatial reference reprojects display, not the source data.
- A layout can hold multiple map frames; a map can appear in several layouts.
- Graduated symbols vary size by a classified value; proportional symbols vary size continuously.
- Label expressions and label classes are easy to confuse - classes split features, expressions format text.
- Layer order in the Contents pane controls draw order (top draws last).
Worked example / rule of thumb
To show population by county with meaningful size differences, use graduated symbols with a classification method such as natural breaks, then set a minimum size so small values remain visible. Rule of thumb: choose symbology by data type - categories get unique values, continuous quantities get graduated colors or symbols.