GIS Marker System
GIS marker symbols are map-based point symbols. They use the E2 icon language inside a map-ready container.
Purpose
Markers represent point features such as places, assets, services, observations, or objects on a map. They must remain spatially interpretable, legible on variable backgrounds, and safe to implement in map engines.
Marker architecture
A marker consists of:
- Container — the outer shape, usually pin or circle.
- Glyph — the simplified icon inside the container.
- Halo or outline — optional contrast layer.
- Anchor metadata — implementation reference point.
Baseline parameters
| Parameter | Requirement |
|---|---|
| Base viewBox | 0 0 48 48 |
| Default visual size | 32–48 px |
| Glyph source | E2 icon system |
| Glyph size | 50–65% of container |
| Anchor model | center or bottom-center |
| Default pin anchor | bottom-center |
| Default pin coordinate | [24, 48] |
| Container stroke | 1–2 px |
| Contrast layer | optional halo or outline |
Anchor model
The anchor is not part of the visual shape itself, but the marker must be designed so a developer can apply one reliable anchor consistently.
Recommended anchor conventions:
| Marker type | Anchor |
|---|---|
| Circle marker | center |
| Pin marker | bottom-center |
| Dot marker | center |
| Cluster marker | center |
For a 48 px pin marker:
{
"anchor": "bottom-center",
"anchorCoordinate": [24, 48]
}Contrast strategy
Markers appear on light maps, dark maps, terrain maps, and satellite imagery. Use at least one of:
- container background
- outline
- halo
- high-contrast glyph
- controlled category color
Semantic encoding
Use visual channels intentionally:
| Channel | Meaning |
|---|---|
| Color | category |
| Size | importance or priority |
| Shape | marker class |
| Glyph | object type |
Avoid encoding more than three simultaneous meanings.
Density behavior
Marker design should support clustering and decluttering. The design system should provide:
- single marker state
- selected marker state
- cluster marker state
- disabled or unavailable state
Do
- Keep glyphs simpler than standalone icons.
- Preserve a consistent anchor assumption.
- Test on light, dark, and satellite basemaps.
- Provide metadata with each marker.
Do not
- Treat a marker as a simple icon with a background only.
- Put small detailed icons inside small markers.
- Use colors that only work on one basemap.
- Change anchor assumptions between visually similar markers.