Analysis of Digital Mapping - Assignment Example

With reference to any THREE (3) d map projections, explain how an understanding of the family, aspect and special property explains the distortions resulting from transforming earth coordinate geometry to a 2-dimensional map.    Mercator Projection In the year 1569, famous Belgian geographer and cartographer Gerardus Mercator developed the method of cylindrical Projection, which was named after him as Mercator Projection. this cylindrical projection method consists of the two latitude and longitude lines that appear to be parallel and perpendicular to each other. the Mercator cylindrical projection is capable f representing the shapes of the various elements of the map in precisely the same manner, however, the drawback of this cylindrical projection method is that the distances between these various elements of the map has shown to be distorted while using the Mercator projection method. this distortion is large for higher latitudes and as a result of this, a map is produced with accurate area and distance representations when representing elements near the earth's equator, and distortions in the elements closer to the poles. as an example, countries lying in the tropical region are shown to be smaller in size (in the Mercator cylindrical projection method) than those lying in the polar region. this distortion in the area led to many troubling issues around the world. one of them was the unfair use of this map projection method by Britain and France during the colonial period to expand their dominance.   Also, the Mercator projection method, was used as the standard method for nautical purposes since it allowed to represent lines of course as straight segments. . This capability of matching and utilization of constant bearing allowed this cylindrical map projection method to be used for almost every shipping and navigational purposes. However, Mercator projection is no longer used in world map projections like atlas maps due to its distortions. Some examples of the Mercator projection distortions are mainly for areas near the poles. the Mercator projection shows that the Greenland is larger than Africa, where in fact, Africa is 14 times larger than Greenland. another example is that of Alaska which is shown to be almost in equal in size to Brazil, which is 5 times larger than Alaska.    Peters Gall Projection This method of cylindrical projection was invented in order to overcome the shortcomings of the Mercator projection method. the Peters Gall method was developed by German historian Dr Arno Peters and British clergyman James Gall in 1973. This method was developed particularly in order to rectify the errors in area representation of countries. this method makes use of the equal-area map concept which shows areas more precisely. as compared to the Mercator projection, the area between the latitudes lines near the poles does not increase in the Peter gall projection method.  this assists in decreasing the area distortion of the Mercator projection method. this projection method developed by Peter and gall received many recommendations from various organizations involved in development of third world countries as it helped them in efficient resource allocation based on areas. however, in spite of its improvements as compared to the Mercator projection method, peter gall method also has significant drawbacks. the projection is unable to accurately show the shape of continents and the shapes of continents are distorted as longer or thinner in the peter gall projections. also, the peter gall projection method suffered from extreme distortions in the pole regions which was normal for any cylindrical projection method. as a result of these shortcomings, the method was not used widely in maps.    Transverse Mercator Map Projection The Transverse Mercator map projection method has been derived from the Mercator projection discussed above. this projection method is widely used in mapping around the world and offers high accuracy in areas which lie in the east - west zone. this cylindrical form of projection uses a reduced scale. in this case, since the central meridian can be selected at will, it leads to making of more accurate maps than other methods, and is generally used for large scale maps. While generating a map, in case the mapping regions are more than a few hundred kilometers in both the x and y axis, then the Transverse Mercator projection suggests the use of a sphere to model the earth. In case, mapping areas are smaller, then the projection method suggests an ellipsoidal model. However, out of the two, the ellipsoidal model offers more accuracy. The main drawback of the transverse Mercator model is that all the other lines except the x and the y axis are complicated curves which makes it a bit complicated. The shapes of small elementary are well preserved in this case, unlike in the sphere model, where shapes of larger elements are distorted to some extent. Moreover, the distortion increases along the x axis and this projection method is not well suited for in the case of world maps. The distortion is less near the areas of  central meridian and the method works best for mapping of smaller regions.     Q.2- Generalisation is a fundamental cartographic process. Explain how it can be applied digitally and what the benefits and drawbacks of this approach might be.  Introduction to Cartographic Generalization  Cartographic generalization is the process in which the mapping information is represented through an adaptable map which is capable of altering its display scale as required by the medium in which the map is being displayed.  Cartographic generalization however, does not makes an attempt to essentially conserve all involved details. The details may both be geographical and cartographic in form. While altering the display scale of the map, it is important that a balance is created between the purpose of showing the map and the reality of the subject under the mapping study. An efficiently generalized map highlights the majority of the significant elements of the map information and presenting the map in a most authentic and familiar manner. Cartographic generalization offers the user the ability to reference any information across each variation in the display. The main of Cartographic generalization is to provide the right amount of information at the selected scaling level and this assists the users to quickly interpret the information and take easy and reliable decisions.  Cartographic generalization might have random consequences on the metrics, topology and semantic characteristics of the map.  With every alteration in the display scale, aspects like the position of an element, characteristics, uniformity and totality may be affected.     Digital Application of Cartographic Generalization With the increasing popularity of the GIS and the requirement for automatic map production capabilities, Automated / Digital cartographic generalization has gained lot of significance lately for mapping agencies and map providers. Digital cartographic generalization is the automated extraction of information related to purpose and scale. The basic of digital cartographic generalization depends on a framework of three main concerns – conditions of when to apply, measures and controls of Digital cartographic generalization.   The main reasons / conditions of applying Digital cartographic generalization are  congestion, coalescence, disagreement, complexity, irregularity, and imperceptibility of a map. The types of measures related to Digital cartographic generalization are the density, allocation, distance, form, and general information conveyed in a map. The most important – controls – the method in which the Digital cartographic generalization is applied is of significant interest in the paper as compared to the other two. The three control parameters of Digital cartographic generalization are operator selection, algorithm selection, and input parameter selection,( MacEachren, 1995).   A significant element of the decision-making procedure is the accessibility and superiority of the generalization operators that are available, along with the types of algorithms that are used by the generalization operators. Each operator works on different specific issues which require a set of different algorithms. While selecting the operator for automated cartographic generalization method, it is important to assess the significance of each individual feature and the importance level each such feature holds for the map and its users, both the inter and intra related complexity of these features which will be affected by the operators, and influence of operators on the clutter level of the map. Regarding the algorithm selection, the subject is relatively obscure and difficult, however, for the purpose of automated cartography generalization, it is important that the concept of algorithm testing should be first tested and applied on the map as per suitability and requirements. The last one – input parameter selection results in more variation in the map characteristics than the above two procedures of operator or algorithm selection.  as discussed above. The input parameter selection affects the location and representation of features at the compact scale.   The main advantages of this approach is that there is a significant decrease in the  spatial and semantic resolutions, which allows an easier generation of both a spatial analysis and map production. Among other advantages are the less use of graphics that is required, the ease of digitally applying colors and patterns in different layer types. It has become much easier to print digital copies and make changes when required. A main drawback of this approach is that the generalization is based on the expertise of the cartographer. His expertise skill set includes his clarity and interpretation skills along with the be deficient of extensibility for multiple representations in GIS. Another drawback is the lack  of a single refined database that has the ability to sustain a number of other related applications. Moreover the absence of a well designed offers to facility to support data derivation,  symbolization, and updating.   Q.3 - For colour, discuss how good design can improve map communication.  The main aim of cartographers is to make a meaningful map. A well designed map should be able to convince the user of its authenticity engage the reader through its text richness and relationships between elements. The variation in the richness of the map is basically a presentation issue for the cartographer and offering several variables in presentation allows for better map making which leads to research and ideas for study. For this purpose, it is important that the cartographer must design the map in such a manner that it is user friendly and offers assistance in understanding the purpose and aim of the map.   Use of colors in maps has been common since the beginning. Colors and their use patterns are commonly consistent on a single map. Colors are used to show the existing relationship between objects, statistical data and between the two at times as well. For example, blue color is used to represent water. Dark blue color is used to show deep waters and lighter blue colors represent shallow waters. In case of  elevations below the sea level, normally a blur grey color pattern is used by the map designers. In case of political maps, which represent more boundaries, use of colors is done to represent to represent the existing landscape features and other human modifications done. Various countries and their states utilize the use of colors in maps. Black color is often used to represent boundaries, while color variations may also be used to differentiate between International, state or county boundary in region. On the other hand, physical maps show the variations in elevation with the help of colors. For example, common elevations in maps are generally represented with the help of green color. Low lying areas are shown with the help of dark green color and higher elevated areas are shown by light green colors. Also, at times, instead of green, brown color variations are also used. Use  of extreme colors like red or purple to show the highest and lowest elevations in maps is common.  Use of colors in maps however do not signify the ground color in reality. That means, if the mountain peaks are in white color, that does not means that they are covered in snow, (Olson, 2001). Color is also used to represent the statistical data on maps. In some special maps called choropleth maps, special color patterns are used to represent data for a particular area. The mapping area in this type of maps will be colored in the same color as the data specified to be represented in the region. These types of maps represent  population, density, life expectancy, health care etc. In case, percentages are to be shown color schemes offer nice visual effects to maps by using different shades. Also, modern software tools help the map makers to apply effective color patterns and schemes for maps, especially thematic maps. These soft wares also help to fill in colors in gaps which might be difficult otherwise. It is important to study the color scheme for maps before start studying and analyzing them as the color schemes are different for different maps, (Olson, 2001). Such soft wares have helped map designers to speed up their work and presentation tactics, besides offering them suggestions on color use and map making. Modern soft wares like Color brewer also offer the facility of making models to check up how the suggested color scheme will work. Due to the importance of designing maps as per suitability, colors assist cartographers in making their maps attractive and user friendly.      REFERENCES   ?         Olson, J. M. (2001). ‘Strategies for Map Colour Selection in the Age of GIS’, Proceedings 97th Annual Meeting of the Association of American Geographers, New York, NY. 27 Feb–3 Mar 2001.   ?         MacEachren, A. M. (1995). How Maps Work: Representation, Visualization, and Design, Guilford, New York Read More