Tagged: 地图和制图

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

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.

In the digital cartography age, it’s easy to overlook traditional paper maps. But they still serve their purpose in our day in age.

The central meridian is the center line of longitude for projection systems. Projected coordinate systems often use it as a reference point for a x-origin.

A basemap is a fundamental building block of cartography that provides geographical context to the map and other dataset layers above it.

A map legend is used to define features in a map. Point, line and polygon symbols in a legend key is the driving-force to understand what is found in a map.

Geology maps depict where the underlying rock formations are. It displays rocks of different ages showing eras, periods and epochs.

Ever wonder where your food comes from? Feast your eyes on these amazing agriculture maps and learn what the future of agriculture holds.

As weather is location-based, GIS can deliver weather information like no other. Rain or shine, these interactive weather maps will brighten your day

A horizontal datum provides a reference frame for latitude and longitude coordinates on the Earth. A datum is constructed through surveys and triangulation.

The equal interval classification method divides attribute values into equal size range taking the data’s minimum and maximum values.

Meade’s Ranch was the focal point of the NAD27 with all positions relative to it. First-order triangulation was used with approximately 26,000 survey points

The State Plane Coordinate System divides the United States into 124 zones to locate any point with a high level of accuracy (one part in 10,000).

Map distortion is best understood looking at Tissot’s indicatrix. It contains circles and shows how map projections distort shape, size and distances.

NAD27 and NAD83 may differ in tens of meters for horizontal accuracy on location. Datum transformations correct your data from one datum to another.

From crop production to melting glaciers, these climate change maps help your grasp a clear understanding of our transforming climate.

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.

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.

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

Satellite and mapping technologies tell a story of our trees and forests. These 4 global forest maps will help you start seeing the forest for the trees.

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.

If you’re serious about geocaching, than you’ve probably heard of benchmark hunting. A survey benchmark is a disk in the ground with a latitude & longitude.

The Magnetic North Pole is a point in Northern Canada where the northern lines of attraction enter the Earth. Compass needles point to the magnetic north.

Mineral extraction, natural gas as well as potential shipping routes. These Arctic Maps display one of the last great frontiers for human development.

Quantile classification divides classes so that the total number of features in each class are approximately the same (which is useful for showing rankings)

This is one of the most comprehensive lists of global transportation maps on the planet. Whether it’s planes, trains or automobiles, you’ll love this guide.

Reference ellipsoids (ex. Clarke Ellipsoid) are smooth, mathematical models of the Earth’s shape. It has a semi-major and minor axis flattened at the poles.

When you place a cylinder around a globe and unravel it, you get the cylindrical projection like the Mercator, Transverse Mercator and Miller projections.

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

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

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.

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.

In a Voronoi Diagram, when you take a point in any given Thiessen polygon, it indicates that it’s closer to that generating point than to any other.

Equal intervals, quantile, natural breaks, pretty breaks- data classification methods generate different choropleth maps. We explain the types of maps here.

The azimuthal projection plots the surface of Earth using a flat plane. For example, common azimuthal projections are gnomonic, stereographic & orthographic

The equal area projection retains the relative size of area throughout a map. So that means at any given region, it keeps the true size and area of features.

Universal Transverse Mercator (UTM) segments the Earth into 60 zones (each UTM zone is 6‎°) and projects each zone with an upright cylinder of its own.

Rhumb lines (or loxodrome) have constant bearings and cross all meridians at the same angle. They are not the shortest distance between 2 points on a sphere

Cartographers use lines to show the movement of phenomenon (people, ideas or money) in flow maps. To show the magnitude, they change the width of flow lines

Cartogram maps distorts reality to convey information. It accomplishes this by resizing and exaggerating any variable using a polygons geometry.

When wildfires burn, satellites (MODIS and VIIRS) track forest fires and deliver warnings to emergency crews. It all goes into real-time active fire maps.

The ultimate list of best maps online. These display state-of-the-art web mapping technology such as live feeds, 3D views and cutting edge visualization.

Geodesy is the field of applied mathematics that studies Earth’s shape, orientation, positions and gravity for the past, present and future.

Latitude lines run east-west, are parallel and go from -90 to +90. Longitude lines run north-south, converge at the poles and are from -180 to +180.

If you’re in need of a visual reference guide to map projection types, this goldmine of the top 50 global map projections used by cartographers will help.

Our ocean’s movements push large amounts of water every day. But where? See this list of ocean currents map and visualize our oceans movement and dynamics.

There are several ways to help readers understand map scale and distance. For example, cartographers use scale bars, locator maps, stated and ratio scale.

When you place a cone on the Earth and unwrap it, this results in a conic projection. Examples are Albers Equal Area Conic and the Lambert Conformal Conic.

Everyday, communities are at risk of transmissible diseases and growing pandemics like COVID-19. We use GIS to track the spread of viruses in real-time maps.

While graduated symbols and proportional symbols scale the size of the symbol based on value, dot distribution maps use dots to represent quantity.

The drive time map is a type of isochrone map that shows you how far you can go based on a start location and an allotted amount of time.

The Web Mercator projection uses a modified version of the Mercator projection and has become a default map projection for web mapping.

Space-time cubes show how phenomena change over time within geographic space. In a space-time cube, each cube represents a slice of time.

Topographers face an uphill battle of a changing geography. These are the top 10 topographic maps built to meet the challenge of accuracy and completeness.

From cartograms to contour maps, cartographers are like heroes. And every hero has a secret. If you want to build unbeatable maps, here are 25 map types.

Airplanes travel along the true shortest route in a 3-dimensional space. This curved route is called a geodesic or great circle route.

Dot maps use dots to show the density of a particular phenomenon in an area. More dots represent a higher density compared to fewer dots.