Conformal projection

Conformal projection pros and cons

Sometimes airports use these to show the cities they fly to. Here are some details on conic projections and how maps use them today. In the Stereographic above, the projection is centered on New York. This means that the distortion is minimized across the entire map. The following definitions are from the widely used "Map Projections" poster distributed by the U. For example, while many readers may be familiar with the Mercator, the less familiar distortions they see on an Azimuthal Equidistant may throw them off or, perhaps, intrigue them and cause them to pay more attention to your map. That is the great circle on which the two points lie. Form — Conformal projections are often good for general-purpose reference mapping, where we want to keep places looking recognizable and familiar. A spheroid can't be flattened to a plane any more easily than a piece of orange peel can be flattened—it will rip. This mathematical transformation is commonly referred to as a map projection. The size of most areas, however, is distorted. Most Equidistant projections have one or more lines in which the length of the line on a map is the same length at map scale as the same line on the globe, regardless of whether it is a great or small circle, or straight or curved. No map projection can preserve shapes of larger regions. One easy way to understand how map projections alter spatial properties is to visualize shining a light through the earth onto a surface, called the projection surface. The projection preserves the ratio of two lengths in the small domain.

Representing the earth's surface in two dimensions causes distortion in the shape, area, distance, or direction of the data. Each has advantages and disadvantages and is better suited to certain situations.

Compromises — Do nothing perfect, but most things well enough If you skim through the example images above, you may notice that, as a general trend, distortions tend to get worse and worse as you get near the edges of the map.

All Tissot's indicatrices of the projections are circles.

mercator projection

Here are some questions to ask yourself when choosing a projection: Is there any specific property that you need to preserve? Any circle on the earth is drawn as a circle or a straight line on the map.

They are more suitable for mapping continental and regional areas.

equivalent projection

For example, in the Sinusoidal projection, the equator and all parallels are their true lengths. Scale is not maintained correctly by any projection throughout an entire map.

spherical projections

This explains the distortion of the conformal projection. What all this means is that we are most worried about distortions when we are doing things like mapping the world, and less when we are mapping smaller areas like cities or states.

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Conformal map projection