Cartographic Techniques
• Cartography refers to the process of conceptualizing, production and dissemination of
a map.
• Art, technology and science of map production
Definition of Cartographic Terms
Map
Is a representation, usually on a plane surface, of all or part of the earth, showing relative size
and position, according to a given projection, of physical features represented and any other
information depending on the intended purpose.
Plan
CADASTRAL plans define property boundaries and determine the enclosed area.
CADASTRAL plans do not normally show much topographical detail other than that which
forms part of the property boundaries.
Right-reading image
It’s an image on film, paper or any other material/medium that reads from left to right on the
emulsion side i.e., the image is on the top side of the material.
Mirror-reversed image
This is an image on the top side of the material and can only be read by viewing through a
mirror. The act of turning the material upside down makes the image readable if it is on a
transparency.
Positive image
A positive image is formed of lines and symbols which are opaque to light on a background
which either allows all light to pass through (transparency) or reflects all the light (a white
background) i.e., image of the original subject which corresponds to the same subject’s
scheme of light and shade - dark for dark and light for light.
Negative image
A negative image is formed by lines and symbols which allow the passage of light on a
background which is opaque to light i.e., the image has reverse tones or lines of those of the
original subject darks are light and lights dark.
The background may be opaque to all light or it may be transparent but colored in such a way
that it stops certain light waves depending upon the requirement. A negative is the opposite of
a positive.
Map grid
It’s a network of Northings and Eastings crossing at right angles to form squares. Usually
used on medium to large scale maps.
1
,Map Graticule
It’s a network lines representing the earth’s parallels and meridians on the map. Usually used
on small scale maps.
Map margin
The space along the edge of the map provided for the printing of the title and other pertinent
and attribute data, separated from the body of the map by the sheet edge, neat line or border.
Drawing Instruments
Ruling or mapping pen
Is used to draw both straight and curved lines. The pens are used in conjunction with either a
straight edge, set-square, French curve or free hand. The thickness of the line can be varied
by turning an adjustable screw to give the thickness (line gauge) required.
Mapping pens
a) Nibs
A nib is the part of a quill, dip pen, fountain pen, ball point or stylus which comes into
contact with the writing surface in order to deposit ink.
Writing nibs range from fine to coarse.
a) Graphos Pen
This is used to draw lines and write letters. A range of writing and drawing nibs are available
for different gauges. There is no setting of the pen to produce the required gauge and the pen
has a reservoir for waterproof ink.
2
,Set squares
Are used as guides when drawing straight lines or used in pairs to set parallel or
perpendicular lines. The set-squares normally are in the form of a right angled triangle and
the other angles are 45°/45° and 60°/30° respectively.
Protractor
ls used to lay out angles and for this reason its edge is graduated in degrees and half degrees.
A protractor is made of transparent material and is either a full or semi-circle.
3
, French curve
ls used for drawing lines around irregular curves. They are of various curves and usually
made of wood or celluloid material.
Railway curves
Are used in drawing arcs of constant radius and they are made of the same material as French
curves.
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• Cartography refers to the process of conceptualizing, production and dissemination of
a map.
• Art, technology and science of map production
Definition of Cartographic Terms
Map
Is a representation, usually on a plane surface, of all or part of the earth, showing relative size
and position, according to a given projection, of physical features represented and any other
information depending on the intended purpose.
Plan
CADASTRAL plans define property boundaries and determine the enclosed area.
CADASTRAL plans do not normally show much topographical detail other than that which
forms part of the property boundaries.
Right-reading image
It’s an image on film, paper or any other material/medium that reads from left to right on the
emulsion side i.e., the image is on the top side of the material.
Mirror-reversed image
This is an image on the top side of the material and can only be read by viewing through a
mirror. The act of turning the material upside down makes the image readable if it is on a
transparency.
Positive image
A positive image is formed of lines and symbols which are opaque to light on a background
which either allows all light to pass through (transparency) or reflects all the light (a white
background) i.e., image of the original subject which corresponds to the same subject’s
scheme of light and shade - dark for dark and light for light.
Negative image
A negative image is formed by lines and symbols which allow the passage of light on a
background which is opaque to light i.e., the image has reverse tones or lines of those of the
original subject darks are light and lights dark.
The background may be opaque to all light or it may be transparent but colored in such a way
that it stops certain light waves depending upon the requirement. A negative is the opposite of
a positive.
Map grid
It’s a network of Northings and Eastings crossing at right angles to form squares. Usually
used on medium to large scale maps.
1
,Map Graticule
It’s a network lines representing the earth’s parallels and meridians on the map. Usually used
on small scale maps.
Map margin
The space along the edge of the map provided for the printing of the title and other pertinent
and attribute data, separated from the body of the map by the sheet edge, neat line or border.
Drawing Instruments
Ruling or mapping pen
Is used to draw both straight and curved lines. The pens are used in conjunction with either a
straight edge, set-square, French curve or free hand. The thickness of the line can be varied
by turning an adjustable screw to give the thickness (line gauge) required.
Mapping pens
a) Nibs
A nib is the part of a quill, dip pen, fountain pen, ball point or stylus which comes into
contact with the writing surface in order to deposit ink.
Writing nibs range from fine to coarse.
a) Graphos Pen
This is used to draw lines and write letters. A range of writing and drawing nibs are available
for different gauges. There is no setting of the pen to produce the required gauge and the pen
has a reservoir for waterproof ink.
2
,Set squares
Are used as guides when drawing straight lines or used in pairs to set parallel or
perpendicular lines. The set-squares normally are in the form of a right angled triangle and
the other angles are 45°/45° and 60°/30° respectively.
Protractor
ls used to lay out angles and for this reason its edge is graduated in degrees and half degrees.
A protractor is made of transparent material and is either a full or semi-circle.
3
, French curve
ls used for drawing lines around irregular curves. They are of various curves and usually
made of wood or celluloid material.
Railway curves
Are used in drawing arcs of constant radius and they are made of the same material as French
curves.
4
