Which projection would be best for easily

I visualized the best-looking shapes and sizes. Then I figured out the mathematical formula to produce that effect. Most mapmakers start with the mathematics.

Interesting: Which map did Christopher Columbus use? Proposed by German cartographer Oswald Winkel in , the Winkel-Tripel projection is quite the opposite of Robinson. This map projection shows Greenland as the same size as Argentina, and not as the size of all of South America. The National Geographic Society has been drawing all its standard maps using the Winkel-Tripel projection since , and many US schools have followed suit.

Must see: These 5 tools will let you master map projections. This is hands-down the most accurate map projection in existence.

In fact, AuthaGraph World Map is so proportionally perfect, it magically folds it into a three-dimensional globe. Japanese architect Hajime Narukawa invented this projection in by equally dividing a spherical surface into 96 triangles. These triangles were then projected onto a tetrahedron, which not only helped maintain the proportions of land and water, but also helped to unfold the map into a perfect, flat rectangle.

Narukawa, however, insists that if the map is refined a step further to increase the number of subdivisions, its accuracy will improve and it can officially be called an area-equal map. Nonetheless, AuthaGraph realistically represents all oceans and continents, including the neglected Antarctica. And while the general shape of the continents is maintained, you will notice that their orientation is skewing upwards — as if in a smile!

This is just popular bollocks. The distortion on Brazil is horrible. Lambert cylindrical projection has existed since the s! Gall—Peters is just one of the many vertically stretched variations. I find it more comprehensible then the AuthaGraph. It, too, is severely east-west compressed. Also, Robinson designed his map to not greatly magnify the Arctic. Yes, Robinson flattens the Arctic a lot, but Robinson must have felt, and I agree, that a more accurate size for the Arctic is more important than accurate shapes for regions there.

Winkel uses extreme horizontal compression to reduce that flattening, thereby making the Arctic more unrealistically large, and making the entire rest of the world too east-west compressed. You said that Winkel scored best in a ratings-study that measured distortions. RMS preferentially fixes the biggest errors. Inside that zone, and usually into the next zone east or west, measurements are quite accurate. But that accuracy fades the farther away from the origin you get.

That means you need to know which zone your map area is in, and it makes UTM a poor choice for national or world maps. OK , you know which projection you want to use, but how to do you get it into that projection? A shapefile actually is a folder containing several files. There are sometimes more, but shapefiles almost always have a. As you might have guessed, the projection information is in the.

Nearly every piece of spatial software will project whatever you want into whatever project you want, as long as you know the SRID you have and the SRID you want. Technically, WGS 84 is not even a projection, and this is an important distinction. A datum is a mathematical model of the earth as a spheroid, and there are actually quite a few different ones in use. The U. Census Bureau uses another un-projected datum, NAD 83, when it releases most if not all of its shapefiles.

Unfortunately, in many cases, the spatial data you receive from a government agency or other source will not include projection information. This is annoying—never do this to someone when you become a powerful government GIS official—and it can be a difficult problem to solve.

Do not guess! There are a few ways you might find the SRID of the new projection you want. Now go to spatialreference. Sometimes known as EPSG This makes things a bit complicated if your map covers a large area, but the advantage is a high degree of accuracy for local maps like a city or metro area. Los Angeles county is in Zone 5. Looks like EPSG is our winner.

And spatialreference. This seems like a minor point, but I have maybe 10 identical shapefiles of the California state border in different projections. Do yourself a favor and include the SRID in the filename e. As I said earlier, we decided that insets for Alaska and Hawaii were the way to go. National Atlas Equal Area Projection, the projection we used for the main map. Map data sources: Natural Earth , U. National Atlas , U.

Michael Corey is a senior news applications developer at Reveal. Sometimes, you won't find a projected coordinate system that is ready-made for your map's purpose.

ArcGIS Pro allows you to modify any coordinate system to have parameters that better suit your needs. Next, you'll learn how to create a custom projected coordinate system using suggested parameters from ArcGIS Pro.

The map you'll make next is narrow enough but doesn't fit properly into an existing UTM zone. In this lesson module, you'll learn how to find the correct UTM projected coordinate system for an area of interest, and how to create a custom projected coordinate system to use when a standard UTM zone doesn't fit.

You want to map the border between Finland and Russia. This will be a reference map, meant to give descriptive context to the border region. You want to use a conformal projection to show the shapes of features in their most recognizable forms. This map currently uses the Web Mercator projection. In addition, this projection distorts area and distances dramatically in higher latitudes. The white rectangle represents the area you want to map.

UTM projected coordinate systems are conformal and their distortion of other map properties is minimal. UTM divides the earth into 60 zones. Next, you'll use a spatial filter to determine which UTM zone to use for your map.

The values under Selected extent update to match the extent of the Map Neatline layer. The XY Coordinate Systems Available list is filtered to only contain coordinate systems with extents that overlap with your map. There are two UTM zones for the area that you want to map, 35N and 36N, and you can't tell from this list which zone is best. Next, you'll add a layer to your map to visualize the UTM grid. UTM projected coordinate systems minimize distortion to reasonable levels, but only within their zone areas.

Neither zone 35 nor 36 will provide this benefit for your map area. Next, you'll create one for this region. ArcGIS Pro can suggest new custom projected coordinate systems based on two criteria: distortion property and map extent. The parameters of the new custom projected coordinate system appear in the Result box.

Transverse Mercator is a common projection, used by the UTM coordinate systems and some State Plate coordinate systems. Transverse Mercator NGA is a variant of this projection, with the added advantage of being able to show a larger portion of the world.

The False Easting shifts the origin point of the coordinate system far away from your map area to ensure that no coordinates have negative values. The new projected coordinate system distorts shapes that are far from its central meridian The image below shows a comparison of the map in the new custom projected coordinate system and in Web Mercator.

In the custom coordinate system, the shape of the neatline polygon is a trapezoid instead of a rectangle. Its northern edge is shorter than its southern edge. The rectangle in Web Mercator is misleading: on the earth, these lines are not the same length. The new projection represents them more accurately. The two maps shown above are drawn at the same scale: 1 to 20 million. But that scale is meaningless in the Web Mercator map, since its area distortions are so extreme.

Distortion in the Transverse Mercator map is small enough to be unnoticeable, and more precise measurements can be made on that map. Earlier in this lesson, you learned how to modify coordinate systems. How could you modify the Equal Earth projection from the start of this lesson to better show the Pacific Ocean?

Change the central meridian to Copy and modify the Equal Earth world coordinate system. In this lesson, you learned some techniques and explored resources that will help you choose an appropriate map projection:. Take a closer look at the maps you see on the internet, in the news, or in apps. Do they use a projection that is well suited to their purpose? Are their distance and area measurements accurate?

The consequences of ignoring your choice of map projection include distorting your data and misleading your map readers. However, if you spend some time to find an appropriate projected coordinate system, you'll create a map that presents your data and your message clearly and accurately. Please send us your feedback regarding this lesson. Tell us what you liked as well as what you didn't. If something in the lesson didn't work, let us know what it was and where in the lesson you encountered it the section name and step number.

Use this form to send us feedback. This course explores categories of map projections and their properties. Learn which projections are best for different types of GIS maps and how to choose a projection for a given mapping project.

In this course, you will learn about why coordinate systems are important and about the two types of coordinate systems used in mapping: geographic coordinate systems and projected coordinate systems. A coordinate system is responsible for ensuring your features display in the right location. You will learn practical guidelines for solving challenges as well as techniques to correct problems caused by unknown and missing coordinate system information.

Lesson Plan Understand projections Learn how different projections distort the world in different ways. Understand projections You will not find a projection that is suitable for all maps. Projection types Conformal projections preserve angles locally, so the shapes of features appear true.

Map global analysis results Map projections distort the grid of latitude and longitude lines, which means they also distort your data. Find a global equal area projection First, you'll explore a few traditional resources to help you find a suitable projection for your analysis results. Download the Projections project package.

Locate the downloaded Projections. Click the Coordinate Systems tab. In the search bar, type Equal Earth and press Enter. Tip: Changing the coordinate system in the Map Properties window affects only the map. Map polar data A compass needle does not point to the true north pole.

Find a polar equidistant projection You'll search for a projected coordinate system that preserves distances from the north pole. At the top of the map view, click the North Pole tab to activate that map. For this map's projection, you have two criteria: To display the arctic data more naturally, you need a projection designed for polar regions.

To determine how close magnetic north is to true north, you need an equidistant projection, which will preserve accurate distance measurements to the north pole. Note: This map currently uses a geographic coordinate system, WGS Tip: Drag the edges of the Map Properties window to make it larger.