# Maps & Cartography

## The Geoid – Hypothetical Mean Sea Level

The geoid measures mean sea level and gravity. The GRACE and GOCE satellites are providing the most accurate measurements of the geoid to this date.

## Vertical Datum – Earth’s Elevation Reference Frame

A vertical datum is a reference surface of zero elevation to which heights are referred to. Datums are used to measure height and depth from mean sea level.

Ellipsoids, survey benchmarks and triangulation – these are the ingredients for geodetic datums. NAD27, NAD83 and WGS84 are common datums in North America.

## Degrees/Minutes/Seconds (DMS) vs Decimal Degrees (DD)

We can find any location on Earth using latitude and longitude coordinates. And we measure those coordinates with decimal degrees or degrees/minutes/seconds

## Greenwich Meridian (Prime Meridian)

The Greenwich Meridian (or Prime Meridian) is a zero degrees longitudinal It is the start-point which we measure 180 degrees east and west.

## Maps for the Dead: A List of the Best Halloween Maps

5 Halloween Maps. Almost all cultures recognize spirits aka the dead. So we bring these 5 maps for the dead to get you in the spirit of Halloween.

## What are Map Projections? (And Why They Are Deceiving To Us)

The best way to represent the Earth is with a globe. But map projections can be awfully useful too. Find out why cartographers use map projections in GIS.

## 33 Map Elements to Include in Cartographic Design

This guide is like your compass – these 33 mapping tips will guide you in the right direction and show you how to create stunning cartographic maps.

## NAD83 – We’re Not in Kansas Anymore

North American Datum of 1983 (NAD83) is 2-meters from geocentric and uses thousands of monuments with triangulation to create a reference frame for Earth

## World Geodetic System (WGS84)

The World Geodetic System 1984 (WGS84) is the spatial reference system of GPS satellites with an error of less than 2 centimeters to the center of Earth.