web mapping glossary and learning bits...
web mapping glossary and learning bits from geospatial revolution mooc...
What is Geography?
HelpGeography is the science of place and space.
It involves the study of spatial (all stuff exists somewhere in space) phenomena of all kinds.
...directions to and from almost anywhere can be had for free in an instant using easy-to-manipulate tools like Google Maps and MapQuest.
So Geography is the science of understanding places and spaces, while Geospatial refers to the data and technologies that allow one to explore Geographic problems. Geospatial is always a modifying term – so I’ll talk about Geospatial information, or geospatial systems, or geospatial bacon, never just “Geospatial” all on its own.
Maps To Tell Stories, Maps To Provide Context
There are two major categories of maps.
Thematic maps are used to showcase geographic data observations. Thematic maps are almost always associated with storytelling of one kind or another.
Reference maps (also frequently called basemaps) provide the basic Geographic context required to situate other stuff. Reference maps are used all the time these days as the backdrops upon which we plop all sorts of digitally-rendered map pins.
Geographic information system - Wikipedia
Un Geographic information system (acronimo: GIS) è un sistema progettato per catturare, immagazzinare, manipolare, analizzare, gestire e rappresentare dati di tipo geografico. L'acronimo GIS è spesso usato per significare la scienza o gli studi sulle informazioni geografiche (dette anche geospaziali); gli studi sulle informazioni geospaziali si riferiscono a discipline accademiche o professioni che usano i GIS
Web mapping is GIS in the cloud. Web mapping includes spatial data in the form of maps, databases, map services, and satellite images, and it also contains tools and functions such as the ability to measure things and to do spatial analysis. .
Not all digital maps are dynamic; millions of maps exist in presentations, PDFs, and as static images .... But unlike static digital maps, dynamic digital maps can show real-time things like weather, floods, or traffic.
Layers of information can be added or subtracted from them so that you can change the map design yourself at will.
The scale, colors, symbols, and the way their data is classified can all be changed.
They can be embedded into live web pages, changed from 2D to 3D, and formatted for a smartphone. Therefore, they move beyond being simply reference documents (“Where is Uzbekistan? OK, great! Next?”) to being tools of geographic inquiry, used to understand spatial and temporal patterns in order to solve problems.
What is an ecoregion?http://en.wikipedia.org/wiki/Ecoregion
An ecoregion (ecological region) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than an ecozone. All three of these are larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remain relatively constant, within an acceptable range of variation (largely undefined at this point).
... we’re also able to use Geography now to share our personal stories in much richer ways...
After you upload your pictures to Flickr, you can say where they were taken by either assigning place information manually (“tagging” a photo of the Eiffel Tower by saying it was taken in Paris) or by uploading coordinates that were captured by a GPS device that you used to track your movements (so you can be much more specific about the exact spot on the earth where the photo was taken)...
It’s this kind of revolution that allows us to tell stories using Geography much more easily than ever before.
The Earth Is Round And Maps Are Flat
To identify a location for anything, we need to set up a reference system. The one we use most commonly is the geographic coordinate system of Latitude and Longitude. Think of it as an addressing system for the entire planet. It’s really just a grid system, with standard lines of Latitude providing North/South parallels and standard lines of Longitude providing East/West meridians. Latitude varies from +/- 90 degrees from the Equator, and Longitude varies from +/- 180 degrees from the Prime Meridian, which runs through the Royal Observatory in Greenwich, England.
a major problem we have to deal with here is that the Earth is a sphere (erm, it’s an imperfect one, so it’s actually an ellipsoid) and we need ways to take stuff off this 3D object and present it in 2D on paper or on screen...n order to make maps, we have to flatten the Earth using math. The act of making transformations to translate points on a sphere (Lat/Long) to points on a 2-dimensional plane (a map) is called Map Projection
Projections allow you to preserve some, but never all of the basic characteristics of Geographic relationships. Specifically, you can preserve direction, shape, area, distance, or the shortest route between locations. Alternatively, you can choose to preserve none of these attributes and instead focus on a compromise across them
Spatial is Special
Most sciences have associated laws and axioms that govern fundamental principles and methodological approaches. In Geography we really just have one; Tobler’s First Law of Geography. In 1970, in a paper describing an urban growth model for the city of Detroit, Waldo Tobler proposed “the first law of geography: that everything is related to everything else, but near things are more related than distant things.”
... Near things are more related, but that doesn’t mean they’re necessarily more similar. The measure of similarity of observations that are close to one another is called spatial autocorrelation. While it’s not necessarily true that stuff nearby is in fact similar, there are often aspects of similarity that can be observed and measured
Thinking like a Geographer
compare places to one another based on their distance and their similarity across a range of attributes
Changing Landscapes
Geospatial technology helps us create content that can be changed.
One type of change that is evident all around us is physical change and demographic change in our own communities.
Unless you have been living under a rock since the 1950s, you know about satellites that have been launched to observe the Moon, Mars, and other objects in our own solar system and beyond. Since the early 1970s, satellites have also been launched specifically to observe the Earth. Some observe oceans, while others observe agricultural health, atmospheric composition, weather, or other phenomena. The first of these was Landsat, short for “land satellite.” Landsat became a series of satellites operated by NASA and the US Geological Survey since 1972. Landsat observes the Earth in the visible and infrared portions of the spectrum. In an infrared image, healthy vegetation appears red, cities appear gray, water appears black, and other interesting colors appear as well. The point is not actually to create weird colors, but that the infrared imagery allows for changes to be detected easily on the landscape, such as urban sprawl, agriculture, deforestation, and fluctuations in water elevation.
The Earth from Above
Geographic image data is raster data, which captures information by assigning values to cells in a grid. A satellite in space can detect visible light or other invisible parts of the electromagnetic spectrum (infrared heat, for example) and assign values to each grid cell to develop an image. The size of those grid cells has an impact on how much resolution (detail) you have in the final image.
The science and technology associated with imaging the Earth from above is called Remote Sensing. It’s a thriving discipline focused on developing new ways of imaging the Earth as well as methods for interpreting and analyzing those images. In addition to the visible photography we all know and love, some sensors use radar, infrared imaging, and even lasers to create maps.
Lasers are now used for Light Detection and Ranging (LIDAR) mapping. This technique is capable of generating extremely high detailed 3-dimensional models of the Earth's surfaceLesson 3
The Global Positioning System (GPS) is no doubt one of the most important methods we have available today for measuring locations. GPS is the system designed by the United States starting in the 1970’s, originally for military purposes, to provide location services around the world using satellites. GPS is one example of a Global Navigation Satellite System (GNSS). There are several others, like the Russian GLONASS (jeez, awkward acronym - comrades) system or the European Union’s Galileo system. Every GNSS works using the same general principle. You need a network of satellites in space to broadcast signals down to Earth that include position information about the location of each satellite as well as the exact time when the signal was sent. A GNSS receiver (like the GPS antenna on your fancy phone) can listen for these signals and compare the times/locations from multiple satellites to triangulate your exact location on Earth.
... there’s an enormous amount of math going on to deal with signals that are constantly moving while you are moving yourself. You can also combine these satellite signals now with cell phone tower signals, wi-fi signals from routers, and other sources to improve accuracy and coverage.
The bottom line is that in the last decade it’s become much more likely for normal people to have access to handheld devices that use a GNSS to determine locations. The consumer-grade stuff you have in your phone or car can figure out where you are to within a few meters in some conditions, while in others you may be several hundred meters off target.
... three location types (point, line, and polygon) comprise the spatial data foundations of modern Geographic Information Systems (GIS). They are considered vector data, because they can represent any kind of geometry. The other major data type is raster data
Geographic image data is raster data, which captures information by assigning values to cells in a grid. A satellite in space can detect visible light or other invisible parts of the electromagnetic spectrum(infrared heat, for example) and assign values to each grid cell to develop an image. The size of those grid cells has an impact on how much resolution (detail) you have in the final image.
The science and technology associated with imaging the Earth from above is called Remote Sensing. It’s a thriving discipline focused on developing new ways of imaging the Earth as well as methods for interpreting and analyzing those images. In addition to the visible photography we all know and love, some sensors use radar, infrared imaging, and even lasers to create maps. Each has its own particular utility – for example, infrared imaging is often used to map the weather and land use.
Who Makes Spatial Data?
Today, the answer is more often than not; Everyone.
It used to be that the primary developers of spatial data were governments, and more specifically, the military.
In the United States, a critically important source for civilian spatial data is the U.S. Census Bureau.
The Census collects all sorts of boundary (points, lines, and polygons – remember?) and attribute data during each decennial population census. These boundaries and their associated attributes allow industry and academia to study changes in population and to analyze social, economic, environmental, and health problems.
The business community often takes these public spatial datasets and modifies them for use in commercial applications.
Most mobile phone contracts allow for carriers to track your movements and what you do with your device all the time. This information is then stored and analyzed
your IP address location is logged
There are now communities of volunteers who actively create spatial data to contribute to the greater good of humanity.
OpenStreetMap wants to create a free alternative that can be used and re-used by anyone for any purpose. OSM data is considered to be Volunteered Geographic Information (VGI), since it is spatial data created on a volunteer-basis. The basic way this works is that volunteers map their community using GPS trackers, or they digitize roads and features using existing satellite images.
Describing Spatial Data
Once you have location information from a GNSS ...you’ll probably want to attach some attributes to that location data.
You could theoretically have all sorts of other additional attributes – you’d just need to define them and collect them
Beyond attributes, spatial datasets are often given broader descriptions to identify information sources, when the data was collected, its overall geographic coverage, and measurements of data quality. This data that describes the data is called metadata.
Fundamentally, mapping involves dealing with uncertainty at multiple levels. You may have to use data from multiple sources, each having its own relative quality.
comma-separated value (CSV) text file its values are separated by commas. The first line acts as a blueprint for the data that follows it: the first line is the header line, containing the field names.You can open the CSV by using a simple text editor or your favorite spreadsheet application.
You can open the CSV by using a simple text editor or your favorite spreadsheet application.
in most everyday speech we refer to “latitude and longitude,” with latitude typically mentioned first. So when plotting point locations it’s tempting to think of these as being equivalent to x, y, with latitude being “x” and longitude being “y.” However, latitude is actually “y” and longitude is “x.” In location-enabled devices and tools, such the GIS you’re using here, latitude and longitude are entered as y and x, respectively.
The Cartesian coordinate system helps us understand why the sign (positive or negative) of latitude and longitude is important. The Equator divides the area above the X axis, the northern hemisphere, from the area below the X axis, the southern hemisphere. The Prime Meridian divides the area to the right of the Y axis, the eastern hemisphere, from the area to the left of the Y axis, the western hemisphere. Any x value to the right, or east, of the Y axis is positive
Therefore, when given the following coordinate pairs, one can determine their correct hemisphere:
X, Y Eastern and northern hemisphere
−X, Y Western and northern hemisphere
X, −Y Eastern and southern hemisphere
−X, −Y Western and southern hemisphere
HelpGeography is the science of place and space.
It involves the study of spatial (all stuff exists somewhere in space) phenomena of all kinds.
...directions to and from almost anywhere can be had for free in an instant using easy-to-manipulate tools like Google Maps and MapQuest.
So Geography is the science of understanding places and spaces, while Geospatial refers to the data and technologies that allow one to explore Geographic problems. Geospatial is always a modifying term – so I’ll talk about Geospatial information, or geospatial systems, or geospatial bacon, never just “Geospatial” all on its own.
Maps To Tell Stories, Maps To Provide Context
There are two major categories of maps.
Thematic maps are used to showcase geographic data observations. Thematic maps are almost always associated with storytelling of one kind or another.
Reference maps (also frequently called basemaps) provide the basic Geographic context required to situate other stuff. Reference maps are used all the time these days as the backdrops upon which we plop all sorts of digitally-rendered map pins.
Geographic information system - Wikipedia
Un Geographic information system (acronimo: GIS) è un sistema progettato per catturare, immagazzinare, manipolare, analizzare, gestire e rappresentare dati di tipo geografico. L'acronimo GIS è spesso usato per significare la scienza o gli studi sulle informazioni geografiche (dette anche geospaziali); gli studi sulle informazioni geospaziali si riferiscono a discipline accademiche o professioni che usano i GIS
Web mapping is GIS in the cloud. Web mapping includes spatial data in the form of maps, databases, map services, and satellite images, and it also contains tools and functions such as the ability to measure things and to do spatial analysis. .
Not all digital maps are dynamic; millions of maps exist in presentations, PDFs, and as static images .... But unlike static digital maps, dynamic digital maps can show real-time things like weather, floods, or traffic.
Layers of information can be added or subtracted from them so that you can change the map design yourself at will.
The scale, colors, symbols, and the way their data is classified can all be changed.
They can be embedded into live web pages, changed from 2D to 3D, and formatted for a smartphone. Therefore, they move beyond being simply reference documents (“Where is Uzbekistan? OK, great! Next?”) to being tools of geographic inquiry, used to understand spatial and temporal patterns in order to solve problems.
What is an ecoregion?http://en.wikipedia.org/wiki/Ecoregion
An ecoregion (ecological region) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than an ecozone. All three of these are larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remain relatively constant, within an acceptable range of variation (largely undefined at this point).
... we’re also able to use Geography now to share our personal stories in much richer ways...
After you upload your pictures to Flickr, you can say where they were taken by either assigning place information manually (“tagging” a photo of the Eiffel Tower by saying it was taken in Paris) or by uploading coordinates that were captured by a GPS device that you used to track your movements (so you can be much more specific about the exact spot on the earth where the photo was taken)...
It’s this kind of revolution that allows us to tell stories using Geography much more easily than ever before.
The Earth Is Round And Maps Are Flat
To identify a location for anything, we need to set up a reference system. The one we use most commonly is the geographic coordinate system of Latitude and Longitude. Think of it as an addressing system for the entire planet. It’s really just a grid system, with standard lines of Latitude providing North/South parallels and standard lines of Longitude providing East/West meridians. Latitude varies from +/- 90 degrees from the Equator, and Longitude varies from +/- 180 degrees from the Prime Meridian, which runs through the Royal Observatory in Greenwich, England.
a major problem we have to deal with here is that the Earth is a sphere (erm, it’s an imperfect one, so it’s actually an ellipsoid) and we need ways to take stuff off this 3D object and present it in 2D on paper or on screen...n order to make maps, we have to flatten the Earth using math. The act of making transformations to translate points on a sphere (Lat/Long) to points on a 2-dimensional plane (a map) is called Map Projection
Projections allow you to preserve some, but never all of the basic characteristics of Geographic relationships. Specifically, you can preserve direction, shape, area, distance, or the shortest route between locations. Alternatively, you can choose to preserve none of these attributes and instead focus on a compromise across them
Spatial is Special
Most sciences have associated laws and axioms that govern fundamental principles and methodological approaches. In Geography we really just have one; Tobler’s First Law of Geography. In 1970, in a paper describing an urban growth model for the city of Detroit, Waldo Tobler proposed “the first law of geography: that everything is related to everything else, but near things are more related than distant things.”
... Near things are more related, but that doesn’t mean they’re necessarily more similar. The measure of similarity of observations that are close to one another is called spatial autocorrelation. While it’s not necessarily true that stuff nearby is in fact similar, there are often aspects of similarity that can be observed and measured
Thinking like a Geographer
compare places to one another based on their distance and their similarity across a range of attributes
Changing Landscapes
Geospatial technology helps us create content that can be changed.
One type of change that is evident all around us is physical change and demographic change in our own communities.
Unless you have been living under a rock since the 1950s, you know about satellites that have been launched to observe the Moon, Mars, and other objects in our own solar system and beyond. Since the early 1970s, satellites have also been launched specifically to observe the Earth. Some observe oceans, while others observe agricultural health, atmospheric composition, weather, or other phenomena. The first of these was Landsat, short for “land satellite.” Landsat became a series of satellites operated by NASA and the US Geological Survey since 1972. Landsat observes the Earth in the visible and infrared portions of the spectrum. In an infrared image, healthy vegetation appears red, cities appear gray, water appears black, and other interesting colors appear as well. The point is not actually to create weird colors, but that the infrared imagery allows for changes to be detected easily on the landscape, such as urban sprawl, agriculture, deforestation, and fluctuations in water elevation.
The Earth from Above
Geographic image data is raster data, which captures information by assigning values to cells in a grid. A satellite in space can detect visible light or other invisible parts of the electromagnetic spectrum (infrared heat, for example) and assign values to each grid cell to develop an image. The size of those grid cells has an impact on how much resolution (detail) you have in the final image.
The science and technology associated with imaging the Earth from above is called Remote Sensing. It’s a thriving discipline focused on developing new ways of imaging the Earth as well as methods for interpreting and analyzing those images. In addition to the visible photography we all know and love, some sensors use radar, infrared imaging, and even lasers to create maps.
Lasers are now used for Light Detection and Ranging (LIDAR) mapping. This technique is capable of generating extremely high detailed 3-dimensional models of the Earth's surfaceLesson 3
The Global Positioning System (GPS) is no doubt one of the most important methods we have available today for measuring locations. GPS is the system designed by the United States starting in the 1970’s, originally for military purposes, to provide location services around the world using satellites. GPS is one example of a Global Navigation Satellite System (GNSS). There are several others, like the Russian GLONASS (jeez, awkward acronym - comrades) system or the European Union’s Galileo system. Every GNSS works using the same general principle. You need a network of satellites in space to broadcast signals down to Earth that include position information about the location of each satellite as well as the exact time when the signal was sent. A GNSS receiver (like the GPS antenna on your fancy phone) can listen for these signals and compare the times/locations from multiple satellites to triangulate your exact location on Earth.
... there’s an enormous amount of math going on to deal with signals that are constantly moving while you are moving yourself. You can also combine these satellite signals now with cell phone tower signals, wi-fi signals from routers, and other sources to improve accuracy and coverage.
The bottom line is that in the last decade it’s become much more likely for normal people to have access to handheld devices that use a GNSS to determine locations. The consumer-grade stuff you have in your phone or car can figure out where you are to within a few meters in some conditions, while in others you may be several hundred meters off target.
... three location types (point, line, and polygon) comprise the spatial data foundations of modern Geographic Information Systems (GIS). They are considered vector data, because they can represent any kind of geometry. The other major data type is raster data
Geographic image data is raster data, which captures information by assigning values to cells in a grid. A satellite in space can detect visible light or other invisible parts of the electromagnetic spectrum(infrared heat, for example) and assign values to each grid cell to develop an image. The size of those grid cells has an impact on how much resolution (detail) you have in the final image.
The science and technology associated with imaging the Earth from above is called Remote Sensing. It’s a thriving discipline focused on developing new ways of imaging the Earth as well as methods for interpreting and analyzing those images. In addition to the visible photography we all know and love, some sensors use radar, infrared imaging, and even lasers to create maps. Each has its own particular utility – for example, infrared imaging is often used to map the weather and land use.
Who Makes Spatial Data?
Today, the answer is more often than not; Everyone.
It used to be that the primary developers of spatial data were governments, and more specifically, the military.
In the United States, a critically important source for civilian spatial data is the U.S. Census Bureau.
The Census collects all sorts of boundary (points, lines, and polygons – remember?) and attribute data during each decennial population census. These boundaries and their associated attributes allow industry and academia to study changes in population and to analyze social, economic, environmental, and health problems.
The business community often takes these public spatial datasets and modifies them for use in commercial applications.
Most mobile phone contracts allow for carriers to track your movements and what you do with your device all the time. This information is then stored and analyzed
your IP address location is logged
There are now communities of volunteers who actively create spatial data to contribute to the greater good of humanity.
OpenStreetMap wants to create a free alternative that can be used and re-used by anyone for any purpose. OSM data is considered to be Volunteered Geographic Information (VGI), since it is spatial data created on a volunteer-basis. The basic way this works is that volunteers map their community using GPS trackers, or they digitize roads and features using existing satellite images.
Describing Spatial Data
Once you have location information from a GNSS ...you’ll probably want to attach some attributes to that location data.
You could theoretically have all sorts of other additional attributes – you’d just need to define them and collect them
Beyond attributes, spatial datasets are often given broader descriptions to identify information sources, when the data was collected, its overall geographic coverage, and measurements of data quality. This data that describes the data is called metadata.
Fundamentally, mapping involves dealing with uncertainty at multiple levels. You may have to use data from multiple sources, each having its own relative quality.
comma-separated value (CSV) text file its values are separated by commas. The first line acts as a blueprint for the data that follows it: the first line is the header line, containing the field names.You can open the CSV by using a simple text editor or your favorite spreadsheet application.
You can open the CSV by using a simple text editor or your favorite spreadsheet application.
in most everyday speech we refer to “latitude and longitude,” with latitude typically mentioned first. So when plotting point locations it’s tempting to think of these as being equivalent to x, y, with latitude being “x” and longitude being “y.” However, latitude is actually “y” and longitude is “x.” In location-enabled devices and tools, such the GIS you’re using here, latitude and longitude are entered as y and x, respectively.
The Cartesian coordinate system helps us understand why the sign (positive or negative) of latitude and longitude is important. The Equator divides the area above the X axis, the northern hemisphere, from the area below the X axis, the southern hemisphere. The Prime Meridian divides the area to the right of the Y axis, the eastern hemisphere, from the area to the left of the Y axis, the western hemisphere. Any x value to the right, or east, of the Y axis is positive
Therefore, when given the following coordinate pairs, one can determine their correct hemisphere:
X, Y Eastern and northern hemisphere
−X, Y Western and northern hemisphere
X, −Y Eastern and southern hemisphere
−X, −Y Western and southern hemisphere