An orthographic projection is the best approximation of a view of the earth from space. It’s an azimuthal perspective projection which creates an illusion of a three-dimensional globe.
It’s an old projection, believed to have first been developed by the Ancient Egyptians and Greeks. In our time this perspective feels natural since our culture has assimilated how our planet looks from a spacecraft. A good example is Earth’s first portrait, taken from Apollo 8 mission astronauts in 1968:
This projection only shows a portion of earth at any given time. Cartographers can use this projection effectively to highlight a particular view of earth in a way that is immediately and intuitively understood.
For our example we are going to be helping people understand Hurricane Basins. We will create custom orthographic maps and then export them as .png files (you could do .svg) to become icons we can use and share. Icons are simplified pictures that represent real things. Quite often they are small so they need to be straightforward and uncomplicated.
Our example is focused on the Hurricane Basins that border the US – Eastern Pacific and North Atlantic. From the ArcGIS Online and Living Atlas bring in Hurricane Basins, World Countries Generalized, and Global Background. Change the World Countries layer to white with no outline and make the Global Background black.
In ArcGIS Pro only two orthographic projections are defined – for the North and South Pole. Thankfully it’s easy to customize the orthographic projection to pivot the planet to be seen from a desired point of view. You may think as if you were on a spacecraft looking down at the earth. All you need then are two coordinates, the latitude and longitude below your viewing position.
Let’s start by making a map of the North Atlantic Basin. Right click on the map and open the Properties. Under Coordinate System select New Projected Coordinate System.
First change the projection to Orthographic.
To highlight the North Atlantic Basin we will center the projection on the coordinates of 44 degrees west longitude (-44) and 20 degrees north latitude. Click Save and OK.
Here’s our new map highlighting the Atlantic Basin.
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