These 5 tools will let you master map projections

Understanding and choosing the right map projection can be tricky. For GeoGeeks it is painful to see the unconscious overuse of Mercator. If you want to change something, start with yourself. These set of tools will let you master map projections, their characteristics, compare them and select the right one for your project.

1. The scale of Mercator projection distortions 

For starters, it’s important to fully get the scale of the problem related to the unconscious use of Mercator projection. This tool called The True Size lets you compare the size of countries by allowing you to move their shapes around a map. In the example below, you can see how the size and shape of the US changes when it’s near the equator and the pole.

2. Understand distortions with Gedymin faces

My favorite image describing map projections comes from the book “Elements of map projection with applications to map and chart construction” written in 1921 by Charles H. Deetz. A similar concept has been further developed in 1950s by a Soviet cartographer named Gedymin who developed an even larger set of heads used to show in an easy to understand way, distortions caused by map projections.

Ningchuan Xiao from the Ohio State University has applied this technique in this awesome tool where you can illustrate the distortions using both Tissot’s indicatrix and the Gedymin faces.

3. Analyze key characteristics of each major projection

Another great tool lets you understand details of some of the key projections out there. Each of the projections is described with name and a couple of parameters:

  • Acc. 40° 150% – The Acceptance index is a numerical measure that summarizes overall projection distortion, in this case with a maximum angular distortion of 40° and areal distortion of up to 150%.
  • Scale – The weighted mean error for overall scale distortion.
  • Areal – The weighted mean error for areal distortion.
  • Angular – The mean angular deformation index.

In other to get it, take a look at Mercator. You can easily say that it’s a conformal projection (preserving the angles) as angular deformation index is zero (while the scale and areal deformations are at the maximum).

4. Compare over 200 projections

This website is probably the biggest repository of map projection knowledge that you’ve ever seen. It features over 200 projections and allows you to easily compare them.

Once you select projections, you can overlay them:

and compare their Tissot’s indicatrix distortions:

5. Find the best projection for your purpose and geography 

Finally, there is also a tool called Projection Wizzard that was designed to help cartographers select an appropriate projection for their map. Depending on the extent and the distortion property of the map, the application returns a list of appropriate map projections with additional projection parameters if necessary.

Say thanks for this article (1)
The Location of Things – Maps, IoT and Digital Twins – GDM #14
Avatar for Muthukumar Kumar
Muthukumar Kumar 06.8.2021
2022 Top 100 Geospatial Companies – Nominations are now open
Avatar for Muthukumar Kumar
Muthukumar Kumar 10.24.2021
Mapping the Haiti earthquake
Avatar for Jo Pratt
Jo Pratt 08.25.2021
Next article

Engaging students through ArcMap and 3 dimensional landscapes

The usage of three-dimensional printers has become a mainstay in the independent production of products. However, these printers could also become the quintessential educational tool.

While geography and history teachers have many methods of teaching at their disposal, the ability to present a landscape in a physical format is far more conducive to the style of tactile learners.

By extension, adding even simplistic examples of three-dimensional printing to a class curriculum gives greater opportunity for more learning styles to succeed, and allows students with vision impairment or blindness a greater opportunity to engage with the course content, especially when teaching a very visual concept like ArcMap.

At present, most public schools don’t receive the funding necessary to include this type of technology. However, by utilizing the advent of personal three-dimensional printing, it’s possible to create basic recreations of topographic structures to improve learning in the classroom. There are feasible and independent methods educators could utilize to incorporate this technology for their students, even if to a lesser extent.

The process of creating topographic renderings and converting them into a miniature three dimensional model is relatively simple. Teaching this process can be done in tandem with instruction on how to import DEM files into ArcMap.

Hand creating these environments requires an open source software, of which I found Blender to be the easiest and most versatile. By using this program, students can reference DEM data to recreate basic imagery of a wide variety of landscapes.

Learning how to use Blender requires very little technical knowledge, and most of what’s needed to learn can be found through their current User Manual, which details the vast amount of functions this software can perform. In simplistic terms, selecting vertices and extending or reducing them and their variant ranges are the primary functions.

Taking a basic plane and splitting the face into several vertices allows the user to manipulate the rendering by any number of points. By selecting individual vertices, it’s possible to change the standard shape into an environment with a variety of detail.

Utilizing Blender, a great variety of landscapes can be modeled, from mountainous landscapes to deep sea trenches.

This methodology could also be applied as a task in the classroom. Having students attempt to recreate environments could bring about a greater grasp on spatial concepts for those who may have trouble visualizing in a three dimensional plane.

Once completed, these models can be exported in .wav or .obj formats and printed through sites such as Thingiverse or Pinshape.

While this is a relatively simplistic method, I’ve found it entirely feasible to conduct in the context of college or public school classrooms.

Read on