Map perspective, specifically referring to perspective projections in cartography, is a method of creating maps by simulating the projection of a globe's features onto a developable surface using a source of light.
Understanding Map Perspective
Based on the provided reference, perspective projections are developed by imagining a light source casting the image of a network of parallels and meridians of a globe onto a surface that can be unrolled or flattened without distortion. These surfaces are known as developable surfaces, such as planes, cones, or cylinders.
This process mimics how light rays would travel from the light source, through the globe, and onto the chosen surface, effectively projecting the geographical grid onto it.
How it Works
- A source of light is positioned relative to a miniature globe.
- The "shadow" or projection of the globe's graticule (parallels and meridians) is cast onto a developable surface (like a plane, cone, or cylinder).
- The surface is then flattened to create the map.
This method contrasts with non-perspective projections.
Perspective vs. Non-Perspective Projections
The reference highlights a key distinction between these two categories of map projections:
| Feature | Perspective Projection | Non-Perspective Projection |
|---|---|---|
| Creation Aid | Uses a source of light | Developed without the help of a source of light |
| Mechanism | Projects globe features (parallels/meridians) | Developed directly onto a flattenable surface |
| Goal | Simulate optical projection | Achieve specific properties (e.g., equal area) |
While perspective projections simulate an optical perspective, non-perspective projections are mathematically constructed to achieve different properties, such as preserving area or shape, without relying on a physical projection model with a light source.
In summary, when discussing map perspective according to the reference, we are referring to map projections created using the principle of geometric projection with a light source.
