The Art and Science of Astrocartics

Cartography, as it has traditionally been, is both the science and art of creating maps. The mapping projections and methods which it uses were made to make maps of the Earth, and thus it is almost entirely concerned with the planet we live on. But if its methods are altered, it can be applied to other terrains in the 3D Cosmos as well.

Astrocartics is a word I have invented as a name for the cartography of 3D outer space. It covers all the various space terrains such as the solar system(s), interstellar space (stellar cartography), galaxies, planet-moon systems, and cosmic-scale intergalactic space (cosmic cartography). The word origin is explained here.

Charting 3D Space

The terrains of Earth which maps try to model arise from the 2D nature of the surface of its spherical shape. It is from this physical nature that the science of Earth Cartography developments the methods and procedures to create maps of the Earth’s surface.

Every planet, moon or otherwise spherical object has a 2D surface terrain like the Earth’s. However, despite the astronomically large number of these objects in the Universe, the far greater volume of space is of a vast 3D space-time nature. Everything in it is a part of it including the 3D sphere of Earth. Therefore, Astrocartics must utilize methods that can model this 3D nature.

One method to model this is to adapt the way we map 2D surfaces. In this case a 2D map can be made with a coordinate system having 3 coordinates. The X-Y coordinates would be replicated on this sort of map as in reality. The Z coordinate would be an abstract numerical associated with each X-Y point. These are called orthographic projections. However, these kinds of maps can be too abstract when used for 3D terrains that have large Z coordinate values when compared to the others. But there is a more visual way.

Human beings do not really see in three dimensions. In our eyes’ vision image we see up-down and left-right. We use our stereoscopic vision and cues from experience to determine the 3rd dimension of front-back. The art of illustration has developed to use these visual cues to reproduce 3D scenes on 2D surfaces. There are two main branches of this: Parallel and Perspective.

Axonometric illustrations are a parallel projection that tries to mimic visual cues without truly using them. The most common are isometric projections that show 3 dimensions using graphic methods that show all three coordinates on a flat 2D surface at the same scale. Axonometric and parallel projection is only touched on here to summarize the method of astrocartics. There are links on this website where the reader can learn more.

Perspective projections try to replicate the true visual image of depth that the eye gives the brain. In these illustrations things that are farther away are smaller as in real life. There a few ways they can be drawn. There are links here to learn more about also.

Astrocartic Chart Classification

Astrocartic charts are maps of volume far more often than maps of the 2D surface of the Earth. Maps of galaxies and star systems usually have a small z axis and need only 2D orthographic projection. But, stars and nebulas within galaxies have large relative z dimensions and use axonometric and perspective projections. Many space terrains can be mapped using any or different projections but some might be better mapped using a particular one. How terrain is related to range, volume, and physics will determine a lot as to which projection is best to use for a particular space terrain.

The inclination of the X and Y coordinate plane of a 3D space terrain has to the 2D map surface is a primary part of the astrocartic chart and can be used to create a classification scheme. The inclination angle determines the most appropriate projection that can be used although most space terrains can be mapped in more than one kind.

The classification scheme presented here divides charts into 3 types based on the angle of the X-Y plane to the chart.

TYPE I

The X-Y plane of this chart type is parallel to the surface of the 2D map. The third dimension for this type is going to be flat and if it is large will have to be labeled with a coordinate number. It can also be graphed, however, as an elevation chart in order to give it a limited visual component. This kind of projection is considered the Plan view in Orthographic projection.

The space terrains this chart is best for are flatter than most such as solar systems and overall maps of galaxies The Astrocartica is of this type using the graphed elevation style.

TYPE II                                                            

This type of chart has an X-Y plane that is inclined at an angle relative to the 2D map surface that may range from greater than 0 degrees to less than 90 degrees. This allows the third dimension to be a visual part of the chart in the same way as the other two when it has a similar magnitude. The best mapping projections for this type is going to be isometric, dimetric, or a similar sort of axonometric projection.

Space terrains that use this type will be interstellar or intergalactic space. However, most terrains can also use this type.

TYPE III

The X-Y plane of this type of chart is perpendicular to the surface of the chart. Perspective projection which uses one or more vanishing points allows this type of chart to be made. The terrain being mapped is projected onto the chart with lines directed to a point that represents the viewer’s eye or camera. This causes the terrain on the chart to appear to recede to a point that vanishes the farther it is from the surface plane of projection.

This type of chart is useful for terrains that have very large 3D dimensional ranges and/or needs to show backgrounds that have objects that are proportionally far away compared to other objects in the chart.