Non-developable surface
Topic: Map Projections · NCERT: Class 11, Ch 4 "Map Projections"
Meaning
A non-developable surface is one that cannot be flattened without shrinking, tearing or creasing it. A sphere or globe is the main example. A sheet of paper laid on a globe touches it only along one line or at one point. Because of this, the earth's graticule can never be moved onto flat paper without some distortion. That is why so many different map projections exist.
Example
Class 6 uses the orange-peel test to show this. Peel an orange and try to press the whole peel flat on a table. It splits and tears before it can lie flat, just as the round earth cannot become a flat map without breaking somewhere.
Don't confuse with
- Developable surface: a cylinder, a cone or a plane can be laid flat without damage. The graticule is first moved onto one of these.
Related concepts
- Developable surface
- Cylindrical projection
- Conical projection
- Zenithal projection
- Normal projection
- Oblique projection
- Polar projection