Vector And Raster Data In Gis Computer Science Essay

Vector And Raster Data In Gis Computer Science Essay A Geographical Information System (GIS) is a method of spatially storing, analysing, manipulating, managing and displaying geographical data. GIS data represents real objects such as roads, rivers, urban areas, place names, railway, places of interest, town names etc. with digital data determining the mix. A geodatabase is a database that is in some way referenced to locations on earth. Traditionally, there are two broad methods used to store data in a GIS; raster images and vector. Ordnance Survey Ireland (OSI) data is supplied in both Vector and Raster format. In both cases the data is geo-referenced. VECTOR AND RASTER DATA Vector data is split into three types; polygon, line (or arc) and point data. Vector is a method for storing spatial data involving assigning coordinates for each entity; an X,Y, Z for a point, a pair of such points for a line and a series of such lines for a polygon. This method is very useful for modeling discrete physical features. Different geographical features are expressed by different types of geometry: Points A point is a zero-dimensional abstraction of an object represented by a single X, Y co-ordinate. It is normally used to represent a geographic feature too small to be displayed as a line or an area (e.g. location of a building on a small scale map or, for example, cities on a map of the world might be represented by points not polygons). No measurements are possible with point features. Figure 1- Vector representation Source: http://www.geom.unimelb.edu.au/gisweb/GISModule/GIST_Vector.html Lines or polylines A set of co-ordinates that represent the shape of geographic features that are too narrow to be displayed as an area, such as, county boundary lines or contours. At small scales geographic features may have no area, e.g. streams or streets and may be represented as linear features rather than as a polygon. Line features can measure distance. Polygons Polygons are used to represent areas. Such as lakes, park boundaries or land uses etc. Polygons convey the most amount of information of the file types and can measure perimeter and area. Rigaux et al. (2002:p.38) states, A point is represented by its pair of coordinates, whereas more complex linear and surfacic objects are represented by structures (lists, sets, arrays) on the point representation. These geometries can be linked to a row in a database that describes their attributes. For example, a database that describes lakes may contain a lakes depth, water quality, pollution level. Different geometries can also be compared and the GIS could be used, for example, to identify all wells (point geometry) that are within one kilometre of a lake (polygon geometry) that has a high level of pollution. Vector data can be displayed at any scale and individual layers (e.g. roads, buildings, etc) can be displayed or omitted (see Appendix A). Raster Ellis states that raster is a method for the storage, processing and display of spatial data. There are three types of raster datasets; thematic data, spectral data and pictures. Raster data consists of rows and columns of cells, with each cell storing a single value. Raster data can be images containing individual dots with colour values, called cells (or pixels), arranged in a rectangular evenly spaced array. Each cell must be rectangular in shape, but not necessarily square (Ellis 2001). Each cell within this matrix contains location co-ordinates as well as an attribute value. The spatial location of each cell is implicitly contained within the ordering of the matrix, unlike a vector structure which stores topology explicitly. Areas containing the same attribute value are recognised as such, however, raster structures cannot identify the boundaries of areas such as polygons. Raster data is an abstraction of the real world where spatial data is expressed as a matrix of cells or pixels with spatial position implicit in the ordering of the pixels. With the raster data model, spatial data is not continuous but divided into discrete units. Ellis states that this makes raster data particularly suitable for certain types of spatial operation, for example overlays or area calculations. Raster structures may lead to increased storage in certain situations, since they store each cell in the matrix regardless of whether it is a feature or simply empty space. Additional values recorded for each cell may be a discrete value, such as land use, a continuous value, such as temperature, or a null value if no data is available. While a raster cell stores a single value, it can be extended by using raster bands to represent RGB (red, green, blue) colours, colour maps (a mapping between a thematic code and RGB value), or an extended attribute table with one row for each unique cell value. The resolution of the raster data set is its cell width in ground units. Anyone who is familiar with digital photography will recognize the Raster graphics pixel as the smallest individual grid unit building block of an image, usually not readily identified as an artifact shape until an image is produced on a very large scale (see Appendix B). A combination of the pixels making up an image colour formation scheme will compose details of an image, as is distinct from the commonly used points, lines, and polygon area location symbols of vector graphics. Aerial photographs and satellite images are examples of raster images used in mapping. Figure 2 Aerial Photo Digitally scanned and ortho-rectified raster colour photography. The ortho-rectification process removes distortions caused by camera tilt and topographical features to produce a scale accurate image. Source: OSI Raster data is stored in various formats; from a standard file-based structure of TIF, JPEG, etc. to binary large object data stored directly in a relational database management system. Raster v Vector There are some important advantages and disadvantages to using a raster or vector data model to represent reality: Vector graphics are usually more aesthetically pleasing. Raster data will appear as an image that may have a blocky appearance for object boundaries (depending on the resolution of the raster file). Vector data is simpler to update and maintain, whereas a raster image will have to be completely reproduced (e.g. a new road is added). Vector data allows much more analysis capability, especially for networks such as roads, rail, telecommunications etc. Distances and areas can be calculated automatically. With raster data it is difficult to adequately represent linear features depending on the cell resolution. Therefore, network linkages are difficult to establish. Vector files require less disk storage space than raster data. Raster data allows easy implementation of overlay operations, which are more difficult with vector data. Raster data structure allows simple spatial analysis procedures An outline of the application of vector and raster data by OSI in Ireland is included in Appendix C. Non-spatial data Relating the spatial component along with the non-spatial attributes of the existing data e.g. census figures (see Appendix D) enhances the users understanding and gives new insights into the patterns and relationships in the data that otherwise would not be found. Non-spatial data can be stored along with the spatial data represented by the coordinates of vector geometry or the position of a raster cell. In vector data, the additional data contains attributes of the feature. In raster data the cell value can store attribute information, but it can also be used as an identifier that can relate to records in another table. Software is currently being developed to support the solutions to spatial problems being integrated with solutions to non-spatial problems. This will result in non experts using GIS to integrate spatial and non spatial criteria to view solutions to complex problems and to assist in decision-making. Data capture The processes of data collection are also variously referred to as data capture, data automation, data conversion, data transfer, data translation, and digitizing. The two main types of data capture are: Primary data sources e.g. those collected in digital format specifically for use in a GIS project. Secondary sources, digital and analog datasets that were collected for a different purpose and need to be converted into a suitable digital format for use in a GIS project. For vector data capture the two main branches are ground surveying and GPS. Survey data can be directly entered into a GIS from digital data collection systems on survey instruments. Positions from a Global Navigation Satellite System like Global Positioning System (GPS), another survey tool, can also be directly entered into a GIS. New technologies allow creating maps as well as analysis directly in the field and as a result projects are more efficient and mapping is more accurate. Remotely sensed data also plays an important role in data collection and consists of sensors (e.g. cameras, digital scanners) attached to a platform which usually consist of aircraft and satellites. The majority of digital data currently comes from photo interpretation of aerial photographs. Workstations are used to digitize features directly from stereo pairs of digital photographs. These systems allow data to be captured in two and three dimensions, with elevations measured directly from a stereo pair using principles of photogrammetry. Photographs are collected by analog or optical cameras before being entered into a soft copy system, but as high quality digital cameras become cheaper this step will be eliminated. Satellite remote sensing provides another important source of spatial data. Remote sensing collects raster data that can be further processed to identify objects and classes of interest, such as forested areas. The disadvantages are that the resolution is often too course or sensors are restricted by cloud cover. Entering data into GIS usually requires editing, to remove errors, or further processing. For vector data it must be made topologically correct before it can be used for some advanced analysis. For example, in a road network, lines must connect with nodes at an intersection. For scanned maps, blemishes on the source map may need to be removed from the resulting raster. To ensure that the data is specific and reliable and that represents as closely as possible the spatial world we live in, it requires a quality insurance process to manage completeness, validity, logical consistency, physical consistency, referential integrity and positional accuracy of data. Raster-to-vector translation Vectorisation is the process of converting raster data into vector data. For example, a GIS may be used to convert a satellite image map to a vector structure by generating lines around all cells with the same classification, while determining the cell spatial relationships. One of the biggest problems with data obtained from external sources is that they can be encoded in many different formats. Many tools have been developed to move data between systems and to reuse data through open application programming interfaces. Therefore, a GIS must be able to convert geographic data from one structure to another. CONCLUSION When data is captured, the user should consider if the data should be captured with either a relative accuracy or absolute accuracy, as this could not only influence how information will be interpreted but also the cost of data capture. Vector data can be manipulated, layers can be turned on and off, data can be edited or deleted and additional data can be added in. Raster data is usually used as a background map. Raster is not as intelligent as Vector, Rigaux et al. (2002: p.39) states the structure is unfortunately not powerful enough to ensure the correctness of the representation. It is more useful as a display map for brochures, internet and power point presentations. Oosterom Van, P.J. (1993:p.vii) states the ever increasing availabilitiy of hardware such as digitizers, scanners workstations, graphic displays, printers and plotters for the input, processing, and output of geographic data only partly explains the growing interest in GISs. GIS allows us to view, understand, question, interpret, and visualise data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts. GIS helps one answer questions and solve problems by looking at data in a way that is quickly understood and easily shared. Figure 3 GIS continues to evolve Source: Cummens 2010 ERSI Many forces are converging transforming how we work and improving efficiency and decision making (see Fig. 3 above). GIS Is becoming Mainstream Technology going beyond focused applications (Cummens 2010). GIS is helping citizens, business and Government by improving planning, management, communications and decision making. REFERENCES Cummens, Patricia (2010) Geographic Information Enabling a Smarter Government and Economy at the SCS Conference 2010. ESRI. Ellis, F. (2001) Introduction to GIS. Melbourne: University of Melbourne. Oosterom Van, P.J. (1993) Reactive Data Structures for Geographic Information Systems. New York: Oxford University Press. Rigaux, P., Scholl, M., Voisard, A (2002) Spatial Databases with Applications to GIS. San Fransisco: Morgan Kaufmann Publishers. http://www.osi.ie/en/academic/third-level-and-academic.aspx?article=4bf958eb-bf0b-4b28-a0d9-24586fadbaab Accessed 27/10/2010

Review of Brazil the Movie Essays -- essays research papers

Upon watching the movie Brazil for the first time, the first thought which comes to mind is ‘WHAT’. However, once past the exterior of the movie, one is able to divine its true meanings. Written by Terry Gilliam, Charlie McKeown and Tom Stoppard, Brazil was a groundbreaking movie which brought to light many issues within society which were valid in 1985 and remain so today. This text is valued because of the issues it raises, such as technology, an unwieldy government and consumerism, which are timeless issues. Brazil is based around a futuristic bureaucracy, where everything and everyone is property, there is little or no communication, and with the right forms, you can legally do whatever you want. This movie shows the flaws of such a system, that whilst aiming for perfection, is merely digging itself deeper into confusion and destroying the very society it seeks to control. Brazil is a dark comedy which shows us the consequences of handing over our lives to a faceless bureaucracy. Sam Lowry’s world is made up of millions upon millions of machines, upon which everyone relies to survive. Machines perform basically every task that there is, from the most mundane task such as creating food, to the most complex and important tasks such as deciding the fate of every living person within the system. When we first meet Sam his alarm clock is not working, the phone is large and hard to work, and the food that his machines make is completely inedible. This does not bode well for the people, for if the machines cannot even handle the most basic of tasks, how could they possibly handle the complex ones? We are taken further into the world of faults and failings within the system later on, when Sam has major problems with his heating ... ...reedom, and that the mind is the only truly safe place. Brazil is a film which rolls up all of the problems which society was experiencing at the time that it was made into one darkly humorous movie. Commercialism, terrorism, technology, bureaucracy and government control, cosmetic surgery and the lack of freedom and individual expression. This movie was not mainstream because of the way that it delivered its message, and also perhaps simply because the government suppressed it somewhat. However, this film provided great insight into these problems, and continues to do so today, as many of these problems continue to exist. Brazil aims to highlight these problems and make the viewer think about what they have seen. This movie was not intended to change the world, but simply to try to prevent it from spiralling down into a dystopian Brazil-like chaos.

Apple and Child Labor Essay

Children and teenagers everyday are put into child labor, to make money for their families or pay back what their families borrowed. In this paper I will examine child labor around the world and why children need to be able to live without being put under such stress and poor living circumstances. I will also be talking about how child labor is involved in some electronic companies like Samsung and Foxconn. Lastly, I will be talking about what most people don’t know; within the last couple years the world’s most known electronic company; Apple, Inc. has been one of the guiltiest culprits of child labor and of poisoning their employee’s. Child labor is known all over the world, and we need to put a stop to it now! Although child labor is illegal in many countries, many children under the age of twelve still are employed in these harsh work forces. Many under age employees are employed by using a fake identification (Thompson). By using a fake identification, children or teenagers can be mistaken for an adult. If the employer says or provides an identification that shows he is age eligible and they accept him for the job, no one would know any different. It is not in the hands of the hiring company to know that the employer is using a fake identification. Children and teenagers are not getting fake identifications and working in these factories for no reason. They are to pay back the money that their family has borrowed from others, or the lack of ability to get an education. Child labor could be caused by problems in the family, with health, or lack of food, money, or water. Multiple governments around the world look the other way. Child labor is illegal but some governments do not punish the companies or groups that use child labor. Child labor is very cruel to the children. Governments and rulers around the world insist that if adults of a family borrow money, the family has to pay it back no matter what, even if it means selling their crops for money or putting their children into the work force. Due to the fact that children and teenagers are working at such a young age, the children are committing suicide and other self-harms. This should not be happening; young adults committing suicide because they are so stressed or they do not want to work at these companies but also because they are being accused of stealing products. For example, one of Apple’s suppliers, Foxconn, accused one of their employees of stealing an iPhone prototype. The employee would not dare to steal an iPhone and would not have done such a thing to get himself in trouble. The possibilities of his pay being withheld and being physically punished was very high for the employee. As a result he killed himself; he did not want to be under the large amount of stress added to the amount that he already had (Usher). This occurs in a lot of work forces, where the employees get so stressed and out of control that they cannot bare to live anymore; it happens especially in electronic factories in Asia. Many people think of child labor being associated with clothing, furniture, or toys, but in reality it’s not. Child labor is known in every industry. One industry that we all use is the electronic industry. Child labor is used in the electronic industry in a big way, not as much as clothing or furniture, but close to it. The Apple IPAD tablet you are holding in your hand, the Apple T.V media portal you are watching shows off of each night, the Apple Iphone you just used to call or text your friend, are all made with the help of child labour. Apple’s major provider Foxconn, has been proven to have employees under the age of Twelve (Usher). Foxconn’s manufacturing plants in Asia have admitted to having child employees that have been poisoned, and some have committed suicide (Usher). This is a situation Apple has a difficult time controlling. The use of child labor in the electronic industry should not be happening at all. It should not be happening in any industry period. Child Labour has been used to try and sabotage the success of certain companies. Samsung was accused of having workers under the age of twelve working in their factories [Thompson]. Samsung has denied the fact that they have underage workers. The rumor was created by RIM (Blackberry) to sabotage Samsung and gain an advantage in the marketplace. Samsung does not have employees under the age of twelve working for them. The name Steve Jobs brings so many amazing thoughts into your head, how he was the co-founder of the largest high tech companies in the wold, the go to guy and CEO of Apple, a multi-billionaire, and philanthropist (In Your Face Radio). Steve Jobs was an amazing man, but in realty he was just like a lot of other top executives, which get carried away with their money and make some bad decisions (In Your Face Radio). Many people think that Jobs was the one who started exploiting children in the business. It was said that Steve Jobs that created the child labor issues in the business because he lost focus and innovation in what he was doing, lost control of his factories and caused such a dilemma in the industry that almost broke the company’s reputation. (Does Steve†¦). Apple’s factory, Foxconn, has been caught with having 164 children in total working in many different factories around the world. (Clarke and Williams). Foxconn has been caught poisoning their employees with n-hexane, and have also been caught for abusing their workers. Tim Costello led a study in Taiwan, and went into to Foxconn and created a report based on the workers lives in Foxconn. The study showed that the company was abusing their employees by â€Å"corporal violence† (Myslewski). Now this is in Foxconn’s factories where they make the parts for the Apple devices. Foxconn has fully admitted to all of the above. The major part of Apple’s manufacturing that is using child labor is Foxconn. As I said earlier Foxconn is the company with over 164 children working in its factory, they have been caught abusing and poisoning their employees. Foxconn is relied upon a lot by Apple. By being caught employing children to manufacture components, has caused an upset within Apple, and the ability to reply on Foxconn has come into question. Apple is an amazing company; however we need to know more about what goes on behind the closed doors within their manufacturing plants and their manufacturing partners facilities. In my opinion Apple is guilty in this situation of child labor. Personally I will continue to use Apple’s products because I believe Foxconn needs to organize their company and other factories that Apple is associated with or Apple needs to find another supplier. In order to fix the crisis of child labor I think that there should be a worldwide legal age to work and which each government must implement. This will decrease the young aged employees that work in countries like India, China, Japan, Pakistan, and many more. Due to there being no worldwide legal working age, problems like child labor occur. Child labor needs to stop, and companies like Apple can lead the way to change just like they have led the way in technology.

The Effects Of Conventional Agricultural Farms On Agriculture

Anyone can have the globe on their dinner plate. Literally speaking, carbon dioxide (CO2), greenhouse gases, and fossil fuel emissions play a role in imported food as does climate change. Conventional agricultural farms are known for being one of the biggest contributors to climate change. Federal policies and subsidies can aid farmers in the fight against altering the climate. Subsidies first allowed cheap commodity crops to flourish during Nixon’s presidency and while they allow farmers to grow, use, and sell cheap produce today, the machinery and transport of it has otherwise been and is destructive to the climate. The amount of fossil fuels and pollution emitted by crop, meat, and fish farms pose as a climatic risk and can be reduced†¦show more content†¦The U.S. Department of Agriculture (USDA) must consign a farm protocol that requires organic soil to be used in croplands which will help eliminate problematic soils caused from CO2 emissions from cultivated farml ands. Everette Burdick, a chemist and former USDA researcher for five years, studied how climate change affects soil in Coral Gables. Burdick states, â€Å"Cultivation of land has been the main CO2 emission source with plant growth and production being jeopardized by changes in the distribution of rainfall†¦this degradation of drylands results in soil exhaustion and erosion. It diminishes soil productivity, and negatively impacts areas not directly affected by its symptoms, by causing floods, soil salinization, and silting of rivers, streams and reservoirs† (1). Continental lands, which include farms, tend to create a buildup in salt production, which is the process of desertification, if the crop soil is affected by rainfall shortages which are affected by CO2 emissions on the climate. In this case, it is possible for the crop to undergo cryptobiosis, a form of de-oxygenation which occurs when soil becomes dehydrated, which then makes the crop ‘dead’ from lack of sustenance. Burdick affirms that, â€Å"The emission limitation