Let's talk about GIS
Welcome all!
With this topic I was in the ranks of users, Habrahabr, for which I would like to thank a friend fatum. Well, now the article itself, carefully pulled out of the drafts.
Today we will focus on geographic information systems, which are every day more and more invade our daily lives. This article will review common questions concerning the principles of remote sensing, one interesting resource that provides satellite images absolutely free of charge, and also raised the question of who and why all this is necessary, what can be done using images or specialized software... All this, of course, will be affected only superficially, since detailed coverage of the issue will require more than one article... so, let's begin.
What are the advantages of remote sensing (i.e. observation and images of the surface of any body from a distance — whether it's getting pictures from a space satellite or a plane, or getting the bottom of the vessel using sonar) over traditional methods of mapping? The most important advantages are the absolute accuracy of the spatial structure of objects and, of course, the possibility of regular updates of data that allows the analysis of multi-temporal data and to reveal the dynamics of present-day landscapes, in simple words to watch for changes, whether the retreat of the forest boundary, associated in most cases with logging, or the drying up of rivers, desertification and other important processes.
From school physics course we all know that electromagnetic waves can be split into spectra, depending on their length. Different spectra of the shooting have a different thematic focus:
the
This, I think, is to finish a bit of boring theory about the pictures and tell you about the Internet primary data sources remote sensing (often abbreviated RSD).
I will tell you quite useful and, most importantly, free online — http://zulu.ssc.nasa.gov/mrsid/mrsid.pl
Here you can get images for 1990 and 2000 from Landsat 4/5 and Landsat 7, respectively. The working principle is as follows:
Click on the map at the desired site until, until you see the desired area-square
Put a checkmark next to the Select Image and click on the desired square (in my case a square N-37-40_2000)
After reloading the page, the resulting pop-up window with the selected plot. Clicking on the sides of this image you can navigate North/South/West/East of the current position. You can change the picture size in the right drop-down list and the degree of approximation in the left drop-down list.
When choosing the scale and size of the image click on the desired portion and obtain the required image
Just below the image is a link to the archive with this image in the format MrSID. After extraction, the image can be opened in a variety of specialized software ArcViewGIS, MapInfo, GlobalMapper and other
The results of processing become different cards. A great example are land use maps of a region made entirely in the picture-based satellite. More laborious is the process of creating a landscape map, as it combines not only the work of "hands", but the "head". Here is an example of a completed topographic map-based images and
On the Internet you can also find quite entertaining card animations obtained using remote sensing data. Here's one such example from the site www.spot-vegetation.com
Here shows the dynamics of vegetation cover throughout the year. It is both clear and informative
Article based on information from habrahabr.ru
With this topic I was in the ranks of users, Habrahabr, for which I would like to thank a friend fatum. Well, now the article itself, carefully pulled out of the drafts.
Today we will focus on geographic information systems, which are every day more and more invade our daily lives. This article will review common questions concerning the principles of remote sensing, one interesting resource that provides satellite images absolutely free of charge, and also raised the question of who and why all this is necessary, what can be done using images or specialized software... All this, of course, will be affected only superficially, since detailed coverage of the issue will require more than one article... so, let's begin.
What are the advantages of remote sensing (i.e. observation and images of the surface of any body from a distance — whether it's getting pictures from a space satellite or a plane, or getting the bottom of the vessel using sonar) over traditional methods of mapping? The most important advantages are the absolute accuracy of the spatial structure of objects and, of course, the possibility of regular updates of data that allows the analysis of multi-temporal data and to reveal the dynamics of present-day landscapes, in simple words to watch for changes, whether the retreat of the forest boundary, associated in most cases with logging, or the drying up of rivers, desertification and other important processes.
From school physics course we all know that electromagnetic waves can be split into spectra, depending on their length. Different spectra of the shooting have a different thematic focus:
the
Blue area. Pictures taken in this area best reflect the shoreline of ponds, they can distinguish different soil types and man-made objects
Green zone. The vegetation stands out and again water features
Red zone. The difference of vegetation type (possible to select different types of forests in shade), tipap soil and anthropogenic objects.
mid-infrared area. Analysis of the snow-ice cover
Thermal infrared area. Logs the fires
This, I think, is to finish a bit of boring theory about the pictures and tell you about the Internet primary data sources remote sensing (often abbreviated RSD).
I will tell you quite useful and, most importantly, free online — http://zulu.ssc.nasa.gov/mrsid/mrsid.pl
Here you can get images for 1990 and 2000 from Landsat 4/5 and Landsat 7, respectively. The working principle is as follows:
Click on the map at the desired site until, until you see the desired area-square
Put a checkmark next to the Select Image and click on the desired square (in my case a square N-37-40_2000)
After reloading the page, the resulting pop-up window with the selected plot. Clicking on the sides of this image you can navigate North/South/West/East of the current position. You can change the picture size in the right drop-down list and the degree of approximation in the left drop-down list.
When choosing the scale and size of the image click on the desired portion and obtain the required image
Just below the image is a link to the archive with this image in the format MrSID. After extraction, the image can be opened in a variety of specialized software ArcViewGIS, MapInfo, GlobalMapper and other
The results of processing become different cards. A great example are land use maps of a region made entirely in the picture-based satellite. More laborious is the process of creating a landscape map, as it combines not only the work of "hands", but the "head". Here is an example of a completed topographic map-based images and
On the Internet you can also find quite entertaining card animations obtained using remote sensing data. Here's one such example from the site www.spot-vegetation.com
Here shows the dynamics of vegetation cover throughout the year. It is both clear and informative
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