1. . Introduction

2. Definition

3. Classification of Maps

4. Mapping

5. Sketch Map

6. Materials Used In a Sketch Mapping For Field or Office Use

7. Procedures for Making a Sketch Map

Purpose: At the end of this chapter, the students should be able to:

♦ Elaborate the differentiate between maps and sketches

♦ Mention some of the main purpose of maps

♦ Classify maps based on scale, use and method of drawing

♦ Sketch some of the most commonly used conversional symbols

♦ Mention procedures and materials used in making sketch maps

Keywords: Sketch Map, Mapping, Scale

Introduction

The oldest map known today is a small clay tablet showing the location of a man’s estate in Mesopotamia dating from about 2800B, C. The ancient Indians and Persians also made good maps. The Chinese, however, developed their cartography to a high degree in very early times. Romans were more interested in a practical map for travel and war, and designed a disk shape map.

The greatest achievement of this age was the triangulation and topographic mapping of France, directed by the members of the cosine family. Map making has become concentrated in large governmental and private offices, producing maps by the millions, reaching great masses of people.

Traditional methods and manual drawing still also may be employed. One can not underestimate the value of the experience of manually plotting as it leads to a much enhanced ability to use and evaluate properly the many features found in maps.

Purpose

Map shows information of the locality that is quantifiable; for example:

♦ Used to show or indicate the exact size or location of a pace.

♦ Used to measure distances between two places with out the need of actual measurement.

♦ Used to indicate the direction of places.

♦ Used to indicate the space or spatial relationship between different phenomena.

♦ Used to locate the number of homesteads in a village even the sanitary facilities.

♦ For planning in office setting.

♦ In epidemiology and public health.

- To indicate distribution of health institutions in an area.

- Spot maps help to follow disease out breaks

- In disease surveillance activities

- To indicate distribution of important diseases that has geographic characteristics such as related to

altitude, latitude or climatic factors.

- To locate health related conditions such as water supply sources, industries, waste disposal sites.

- To facilitate service delivery such as spray activities in malaria control, have visit service, etc.

Definition

A map is a simplified selective, symbolized diminished and a plane representation of a part or the whole of the earth’s surface on a piece of paper. A map provides a bird’s eye view of the earth’s surface or a part of it.

The map makers are always selective and should limit the amount of information to be shown on the map. Otherwise, the map becomes difficult to read or it would be over crowded and confusing. This shows that in any map the information is summarized or simplified by avoiding unnecessary details.

The features of the earth in any map are reduced or diminished in size because the drawing of maps which is exactly equal to the area of the place to be mapped is impossible.

Classification of maps

The types of map depend on the size of the map and the purpose of the map. The size of the amp on the other hand, depends on the amount of information that the map maker wants to show. Depending on this, maps are divided in to three categories.

1. On The Basis Of Scale:- maps are divided in to three groups. These are:-

A. Large scale map

B. Medium scale map

C. Small scale map

♦ Large scale maps:- are maps with the scale of > 1:50,000 (one to fifty thousand). Such maps can

cover small area but they show very detailed information.

♦ Medium scale maps:- are maps with a scale between 1:50,000 and 1:250,000 (One to fifty

thousand and one to two hundred and fifty thousand). Here the area to be covered is larger while the

amount of information shown is smaller than the large scale map. These maps can’t cover large areas.

♦ Small scale maps:- are maps with a scale of <1=250,000 (one to two hundred and fifty thousand).

Such maps can cover large areas but the information is highly summarized. Therefore, they are suitable for

drawing the map of a country, continent, world, etc.

2. On The Basis Of Their Uses

Maps are divided in to two major groups on the basis of their uses. These are:-

♦ Topographic maps:- are maps that are used to show all man made and natural features of a given place in one map. E.g relief features, human activities, soil type, population distribution etc. They are some times

known as general reference maps.

Figure1 Topographic maps

♦ Topical maps:- are maps that are used to show one particular feature of a given place. Eg. Climate map,

population density map, vegetation map, etc. the best examples of topical maps are the followings:

a. Mobility maps- are the maps that are used to show the pattern of roads, railways, ship routes, airlines, etc. b. Inventory maps – like thematic maps they consider specific feature. But in this case the maps are used to show the exact or precise location of an object.

c. Thematic maps – are the maps that show the distribution of one particular object in a given place. Eg. The distribution of population in a certain locality.

Topical Maps

3. One The Bases Of How The Maps Are Drawn:

♦ Scaled maps

♦ Air photographed maps

♦ Sketch maps

♦ Block maps

For small jobs traditional methods and manual drawing still may be employed. From an educational stand point, one can not under estimate the value of the experience of manually plotting a map as it leads to a much- enhanced ability to use and evaluate properly the main features found in maps.

Sketch map is one that may be utilized in small public health projects and would serve its purpose.

It is a map which can be performed with in short period of time when compared to other maps. As a result this manual focused only on a sketch map.

Sketch Map

Definition:- a sketch is a free hand drawing of a map or picture of an area or route of travel. It shows enough detail of a locality. Sketches are useful when maps are not available or the existing maps are not adequate.

Sketches may vary from hasty to complete and detailed, depending up on their purpose and the degree of accuracy required. For e.g. a sketch of a large minefield will require more accuracy than a sketch map of small village.

A Sketch map should include:

♦ Title of the sketch map: It includes name of the location and the date in which the sketch map was

done. Eg. Sketch map of Awaday Town, Kebele 04, sept, 2002 Usually the title of sketch map answers the questions: what where & when

♦ The North line (direction): It should be drawn close to and parallel with the upper right hand edge of the

map sheet.

♦ Symbols: Are conventional signs or assigned symbols, which represent both natural and man made

features on the map.

Figure Symbols

♦ Legend (key): indicates the meaning of all the mapping symbols used. It appears in the lower right

hand corner of the map sheet.

Details: such as the total population, number of houses, highest and lowest elevation are also shown

if any. This appears on the top right hand corner of the sketch map sheet.

♦ Natural and cultural (man made ) features:

Including all water sources (rivers, wells, springs, swamps, lakes and reservoirs) with their name and appropriate direction of flow; markets, schools, police stations, post offices, telephone offices, hospitals, health stations, roads, bridges, mountains, etc. should be shown.

♦ Boundaries: The locality boundaries should be indicated in their correct relative position with the neighboring areas (kebeles, ketena, etc.) N.B – A locality is a small geographical unit with defined boundaries.

♦ Scale: The scale used to convert actual ground measurement in to paper size.

♦ Name of the drawer and the person checking the sketch map: The name of a person (s) who drew the

sketch map and the person checking it should be indicated.

♦ Boarder line: are lines drawn all around the sheet leaving a margin of 10mm. A margin of 25 or 30 mm

is left on the left hand side so as to facilitate filing. Title block is drawn on the right hand side or right hand side bottom corner. The remaining space is utilized for making drawings.

Materials used in a sketch mapping for field or office use

♦ Map board (Portable drawing board) 42x45 cm.

♦ Magnetic compass

♦ Ruler of 40 cm length

♦ Appropriate size of drawing paper

♦ Pencil (HB soft) with eraser

♦ Pencil sharpener (pocket size)

♦ Thumb-tacks or scotch tape

♦ Paper clips

♦ Altimeter 0-3000 meters if possible.

♦ A clip board

♦ A haver sac (bag)

Procedures for making a sketch map

1. Make a survey of the specific location to be drawn.

Observe the area from a high point to see lay out of the location (eg. From top if a hill, building, etc.)

2. Select land marks, reference point or bench mark of the location: Land marks a location are prominent and permanent features which are expected to be there incase somebody wished to return to the place at a later dates. Examples of landmarks are: rivers, bridges, lakes, mountains, market places, schools, police stations, health centers, etc.

3. Proceed sketching: Locate such details as the location of each households, churches, mosques, shops, stores, factories etc. with their proper orientation and compass direction to each other. Draw the actual shapes of the buildings as of their top plan.

Слайдтар: Mapping

Ұсынылатын әдебиеттер тізімі:

1. Wuttet Taffesse, Laikemariam Kassa. Engineering Drawing. The Carter Center, the Ethiopia Ministry of Health, and the Ethiopia Ministry of Education. 2005

2. Bryant, Michele Wesen, Fashion Drawing: Illustration Techniques for Fashion Designers, Pearson, Prentice Hall, 2011.

Бақылау сұрақтары

1. Explain the difference between maps and sketches

2. Classify maps based on scales used and method of drawings

3. Mention the procedures and materials used in making sketches

Lecture №15-16. What is Computer Graphics?

1 Bitmap Images

2 Vector Images

3 Image Size and Resolution Settings

Purpose: Create bitmaps and vectors. To know advantages and disadvantages of bitmap and vector images. Own file formats in vector graphics.

Keywords: Bitmap Images, Bitmap Advantages, Vector Images

Bitmap Advantages

Following are some of the benefits of using the bitmap images:

Bitmaps are very easy to create. Take a picture with a digital camera, or scan something in, and you’ve got one.

Bitmaps are fairly simple to output, as long as your RIP or printer has sufficient memory.

They are easy to come by.

They are very cost effective. You can take a picture or scan in a drawing, and easily show it on the Internet or send in an email.

A bitmap image uses solid color pixels, which can be identified and recolored easily.

The geographic location of each cell is implied by its position in the cell matrix. Accordingly, other than an origin point, e.g. bottom left corner, no geographic coordinates are stored.

Bitmap Disadvantages

However bitmap images have some drawbacks too. A few common disadvantages of these format are as follows:

• The most common and obvious disadvantage of these image format is that they are not upward scalable. You can make a bitmap smaller without to much loss, but you cannot make it larger without loosing quality. If you ever see a bitmap image blown up, you’ll notice it has little individual squares or dots that make up the image. When you see it at its optimal size you don’t notice the individual dots, but if you try to make it bigger, the image become fuzzy, jaggy or pixelated.

• Another disadvantage of bitmap images is that they require higher resolutions and anti-aliasing for a smooth appearance.

• The bmp file has been created by microsoft and ibm and is therefor very strictly bound to the architecture of the main hardware platform that both companies support.

That is all about the Bitmaps. 

Vector Images

Vector images are quite different from the bitmaps. As told earlier the bitmap images are made up of pixels but the vector graphics are not made of pixels, instead mathematical formulas called “lines and curves” form shapes that in turn make up a vector image. In this case the computer therefore does not read a list of coloured dots but it look up at the mathematical formula that creates these shapes.

Vector images are the graphical representation of geometrical entities such as circles, rectangles or segments. You can enlarge the vector images as much as you want, you will never see a single pixel.

Vector images are represented by mathematical formulae. A few examples are as follows:

A rectangle is represented by two dots.

A circle by a centre and a radius

A curve by several points and an equation

The computer processor will translate these mathematical calculations into such an information that a can be interpreted by the graphics card.

Vector images are created through the process of drawing with vector illustration programs such as CorelDRAW or Adobe Illustrator. The word “vector” is a synonym for line. Vector images can also be created through the process of conversion from a raster image by using a raster to vector conversion program such as CorelTRACE or EuroVECTOR. The most common vector image you come in contact with every day, is type. The type you are reading on the screen right now is vector based.

File Size of Vector Images

We now know that unlike the pixelated bitmap images the vector graphics are made up by the mathematical calculations. Today we will lean how this particular feature of vector images affect the file size of these file formats.

File size of vector images:

Vector drawings are usually pretty small files because they only contain data about the Bézier curves that form the drawing. The EPS file format that is often used to store vector drawings includes a bitmap preview image along the Bézier data. The file size of this preview image is usually larger than the actual Bézier data themselves.

As we discussed earlier the vector images make it possible to define an image with very little information. This feature of vector graphics makes the file weight quite small. Moreover unlike the bitmap images the quality of vector graphics is not dependent on the screen resolution of the monitor screen of the viewer. They look alike on all screen resolutions.

How scaling is done in vector images:

When an illustration (drawing) program sizes a vector image up or down, it simply multiplies the mathematical description of the object by a scaling factor. For example a 1″ square object would need to be multiplied by a factor of 2 in order to double in size. The math is simply recalculated to produce an object twice the size of the original.

Where vector images can be used

As we have discussed earlier the vector images are highly salable, therefore they are often used to create logos. A vector logo can be easily scaled down to fit on a business card, or scaled up to fit on a tradeshow display, the side of a van or bus, or larger without losing quality.

Vector images can also have transparent backgrounds, making them easy to place or layer on top of other graphics.

Advantages of Vector images:

Vector images have a number of advantages over bitmap images, including:

• The most important and obvious plus point of vector images is their power of scalability. If you try to enlarge a bitmap image, your computer can only enlarge the size of the squares making up the image area. That is why bitmap images get jagged as you enlarge them. However on the other hand the vector images remain smooth because your computer merely re-computes the coordinates of the points and adjusts the vector equation constants.

• Each set of lines in a vector image represent separate and distinct objects. therefore every object can be re-edited at any time. For example, let’s say you created a vector art file with a circle in the background. You could open the drawing file at any time – even days later – and change the circle to a square.

• Another very important reason of using vector images instead of bitmaps is their size. Vector images are much smaller in size than the bitmap image format. If you had a very large picture – such as a poster on your wall – the vector file might only take up a few kilobytes of space on your computer, while the same image in a medium resolution bitmap format might not fit on a CD-ROM!

Some disadvantages

However there are some disadvantages of these images as well. A few are as follow:

• Drawings containing trapping information can only be scaled up to 20 percent larger or smaller.

• Thin lines may disappear if a vector drawing is reduced too much.

• Small errors in a drawing may become visible as soon as it is enlarged too much.

• Another important disadvantage of vector is the time and talent needed to create it. You cannot take a photograph in vector. Vector images are drawn on the computer by a graphic artist using vector editing software such as Adobe Illustrator.

• Because of the above mentioned reason the vector graphics are not as cost effective as bitmap images.