What determines the scale of a map in GIS?

What determines the scale of a map in a Geographical Information System? There is a fantastic post about cartographic scale on the National Geographic site. The article makes the point that as the scale of a map changes then the cartographer is faced with choices. When producing smaller scale maps (think ship-in-a-bottle) that cover large…

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GIS Analyst – What Does One Do?

A gis analyst

What is a GIS Analyst? In other posts I’ve talked about the many aspects of GIS, particularly the technology, issues with data, and the way GIS technology is used. In this post I want to talk about the people who pull a GIS project together – GIS analysts. Ideally a GIS analyst is someone who…

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Using Remote Sensing for Arctic and Antarctic Sea Ice Change Detection

Using 25km daily remote sensing grid cell data from a satellite mounted microwave sensor, National Snow and Ice Data Centre (NSIDC) scientists have shown that the minimum extent of Arctic summer sea ice is almost half that detected in the late 1970s. As with any remote sensing data, the NSIDC tempered their interpretation with both…

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Choropleth Map Data Classification

Choropleth Map Data Classification A Choropleth Map is also known as a Shaded Map and a Thematic Map Today, I am going to talk about Choropleth Map Data Classification. This is a very important part of GIS, and this article will help you gain better insight into the process. Be sure to comment below, if…

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Mapping Links Pollution to Regulation

Map 1: The earlier of two images on acid rain – 1985 Map 2: The latter of two images on acid rain – 2008 Time-series GIS mapping of a 25 year study of acid rain frequency and intensity in the United States shows a decrease over time. Acid rain is rain or snowfall with a pH…

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What is Quantum GIS

What is Quantum GIS What is Quantum GIS (QGIS) – its a brand of Geographical Information System that is Open Source and so free. Its been around since around 2002 and these days is similarly functional to commercial Geographical Information Systems. In order to understand what Quantum GIS is, lets have a quick look at…

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What is GIS used for? Here’s ten ways…

Geographic information system (GIS) technology can be used for a wide variety of applications. GIS can gather, manipulate, store, and analyze geographic data which makes it useful for government, researchers and business. Following are ten common uses for GIS…

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What is Spatial Data

Line, Polyline, Polygon and Point

What is Spatial Data The four simple map structures in a GIS are Points, Lines, Polylines and Polygons. If you were to on-screen digitize the figure above then each of the circles (nodes) represent a mouse-click. There are four basic mapping structures in a GIS – Points, Lines, Polylines and Polygons… Points: You should think…

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Analysis of the census using GIS

Analysis of the census using GIS is an important  geography career! Most countries around the world conduct a regular National Census. Censuses date back to biblical times. A big reason for them has always been the need to understand how many people should be paying taxes and how much! These days the reasons are a little…

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Roadlessness as a Conservation Measure

In mid 2012, Google was approached by Kriton Arsenis, a Member of the European Parliament and its rapporteur on forests. He made the point that keeping an area roadless means that a territory is shielded against deforestation pressures. This provided an incentive for Google to investigate. Google buffered their road map by 10 km and…

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