3. Raster and Vector GIS measurement

Question 3a Raster Gis Distance measurement C = [3x300]²+[7x100]² Euclidian Manhattan M = 3 X 300 + 7 X 100 = 1600 m C Source : Google Maps = 1140.17 m

3b. Vector GIS Area measurement A B F C D E 600 m Source : Google Maps

Formulation Area of rectangular Area = Length x Width Area of triangular Area = ½ Length x Width What total Area of Caird Park ?

Area of rectangular

Area = Length x Width

Area of triangular

Area = ½ Length x Width

Area A and B Area A = 550 x 375  206250 m² Area B = 1100 x 300  330000 m² Source : Google Maps

Area A = 550 x 375  206250 m²

Area B = 1100 x 300  330000 m²

Area C, D and E Area C = ½ 550 x 600  175000 m² Area D = ½ 300 x 50  7500 m² Area E = ½ 250 x 50  6250 m² Source : Google Maps

Area C = ½ 550 x 600  175000 m²

Area D = ½ 300 x 50  7500 m²

Area E = ½ 250 x 50  6250 m²

Area F Area F = ½ 1050 x 250  131250 m² Source : Google Maps Area A = 206250 m² Area B = 330000 m² Area C = 175000 m² Area D = 7500 m² Area E = 6250 m² Area F = 131250 m² Total = 846250 m² Approx True ????

Area F = ½ 1050 x 250  131250 m²

Area A = 206250 m²

Area B = 330000 m²

Area C = 175000 m²

Area D = 7500 m²

Area E = 6250 m²

Area F = 131250 m²

Total = 846250 m² Approx True ????

So what is wrong ? Area C = 165000 m²

4. Six Key elements of map design ? Frame Of Reference Projection Used Feature to be Mapped Level Of generalization Annotation Symbolism

Frame Of Reference

Projection Used

Feature to be Mapped

Level Of generalization

Annotation

Symbolism

Question ? How far does the car move ? Where does it move ? 1 5 7 N m

How far does the car move ?

Where does it move ?

Question : The Frame reference Heywood, et.al, An Introduction to GIS, p255

What are the 6 key maps design elements Frame Reference A map is scale model of the real world so it needs some form of spatial reference so the user can fix its location in the real world . Mechanism that can be used to provide this: A grid with lines (representing latitude longitude) or planar (x.y) co-ordinates A north arrow in conjunction with a scale bar An inset map

A map is scale model of the real world so it needs some form of spatial reference so the user can fix its location in the real world . Mechanism that can be used to provide this:

A grid with lines (representing latitude longitude) or planar (x.y) co-ordinates

A north arrow in conjunction with a scale bar

An inset map

What are the 6 key maps design elements Projection Used Map projections can radically affect measurements such as area or distance. Small scale maps of larger areas are more affected by the projection method. For maps of large areas, decision need to be made regarding what is most important (i.e. area, distance, directions, lines of true scale etc) Heywood, et.al, An Introduction to GIS, p47

Map projections can radically affect measurements such as area or distance. Small scale maps of larger areas are more affected by the projection method. For maps of large areas, decision need to be made regarding what is most important (i.e. area, distance, directions, lines of true scale etc)

Question Heywood, et.al, An Introduction to GIS, p255 Projection

What are the 6 key maps design elements Features to be mapped Maps are by definition a communication device for spatial information, so it is important that the map shows only what is necessary to get that intended message . It should contain no distractions Source : Google Maps

Maps are by definition a communication device for spatial information, so it is important that the map shows only what is necessary to get that intended message . It should contain no distractions

What are the 6 key maps design elements Level of generalisation Balance of detail is critical. Too much – map is difficult to read, too little – map may be missing vital information. Deciding what to ‘leave in’ or ‘leave out’ is a difficult choice. (For example, in designing a road map – which smaller roads would you leave out? This would depend greatly on why you are mapping the roads... What makes an individual road more or less significant than another ? In all depends on context. Source : Google Maps

Balance of detail is critical. Too much – map is difficult to read, too little – map may be missing vital information. Deciding what to ‘leave in’ or ‘leave out’ is a difficult choice. (For example, in designing a road map – which smaller roads would you leave out? This would depend greatly on why you are mapping the roads... What makes an individual road more or less significant than another ? In all depends on context.

What are the 6 key maps design elements Annotation Annotation is textual and graphical information that labels the maps, details the features or provides supplementary information. It should be appropriate and economic. Examples of annotation: numerical guides, frame of reference (also a form of annotation), map title, legend.

Annotation is textual and graphical information that labels the maps, details the features or provides supplementary information. It should be appropriate and economic. Examples of annotation: numerical guides, frame of reference (also a form of annotation), map title, legend.

Question Heywood, et.al, An Introduction to GIS, p255 Annotation

What are the 6 key maps design elements Symbolism Symbols used on the map to represent the real world . Symbols on a map are either, points, lines or areas. Shape and pattern of symbols should also bear some relation to the feature being represented. Whatever symbols are decided upon, a ‘legend’ or ‘key’ must be provided so the users understand what they are looking at . Colours are also important. They should where possible match the real world i.e. Rivers should be blue, forests - green so as not to confuse users. If you coloured a river black, users may think it’s a road http://www.simmons.edu/i/maps/mapOverviewDetails.png

Symbols used on the map to represent the real world . Symbols on a map are either, points, lines or areas. Shape and pattern of symbols should also bear some relation to the feature being represented. Whatever symbols are decided upon, a ‘legend’ or ‘key’ must be provided so the users understand what they are looking at . Colours are also important. They should where possible match the real world i.e. Rivers should be blue, forests - green so as not to confuse users. If you coloured a river black, users may think it’s a road

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