Specialized
Isoline / Contour Chart
Lines connecting equal values - like elevation contours on a topographic map.
Terrain Elevation
49-point grid (7×7 km), elevation 100-330m
View data (49 rows)
| X | Y | Elevation |
|---|---|---|
| 0 | 0 | 136 |
| 0 | 1 | 172 |
| 0 | 2 | 173 |
| 0 | 3 | 139 |
| 0 | 4 | 113 |
| 0 | 5 | 105 |
| 0 | 6 | 102 |
| 1 | 0 | 151 |
| 1 | 1 | 204 |
| 1 | 2 | 210 |
| 1 | 3 | 167 |
| 1 | 4 | 133 |
| 1 | 5 | 118 |
| 1 | 6 | 109 |
| 2 | 0 | 138 |
| 2 | 1 | 182 |
| 2 | 2 | 201 |
| 2 | 3 | 189 |
| 2 | 4 | 174 |
| 2 | 5 | 154 |
| 2 | 6 | 130 |
| 3 | 0 | 119 |
| 3 | 1 | 150 |
| 3 | 2 | 190 |
| 3 | 3 | 229 |
| 3 | 4 | 245 |
| 3 | 5 | 217 |
| 3 | 6 | 165 |
| 4 | 0 | 111 |
| 4 | 1 | 141 |
| 4 | 2 | 200 |
| 4 | 3 | 275 |
| 4 | 4 | 310 |
| 4 | 5 | 272 |
| 4 | 6 | 196 |
| 5 | 0 | 109 |
| 5 | 1 | 137 |
| 5 | 2 | 196 |
| 5 | 3 | 273 |
| 5 | 4 | 310 |
| 5 | 5 | 272 |
| 5 | 6 | 196 |
| 6 | 0 | 106 |
| 6 | 1 | 124 |
| 6 | 2 | 165 |
| 6 | 3 | 217 |
| 6 | 4 | 242 |
| 6 | 5 | 217 |
| 6 | 6 | 165 |
Use an isoline / contour chart when…
- Continuous spatial data
- Weather maps (isotherms, isobars)
- Terrain and density visualization
Avoid when…
- Discrete data
- Non-spatial data
Data it needs
| Property | Value |
|---|---|
| Min Rows | 9 |
| Min Columns | 3 |
| Column Types | numbernumbernumber |
Visual anatomy
Marks
contour line
Channels
positionline-value
Axes
x-spatialy-spatial
Guiding principles
Consider instead
Common mistakes
Contour intervals too large hiding detail
Missing elevation/value labels on lines
Failing to highlight peak/saddle features that anchor the reader's interpretation
History
Originated in cartography; Edmond Halley drew the first isoline map (1701) showing magnetic declination.
Accessibility notes
Label contour lines with values. Describe overall shape of the field.
Related reading
Got data? Let's see what works.
Drop your CSV. You'll get an Isoline / Contour Chart plus four alternatives - ranked by which one actually fits your data best.