The Dictionary of Human Geography

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RS data can be ambiguous, requiring careful

interpretation.

One problem is that as RS signals pass

through (for example) cloud cover and the

atmosphere the signals are degraded. Second,

although commercial satellites now offer very

precise imagery (1–5 m resolution), if these

are unavailable and if an object is smaller than

the resolution offered by the sensor, then its

spectral properties will be mixed with others

around. Third, objects can be obscured by

others above; for example, vegetation below a

tree canopy.

In any case, human geographers may be less

interested in land coverper seand more con-

cerned withland use, or the social meaning

given toplaces. A spectral signature is a co-

production ofnatureandscience; the way in

which places are constructed and used is

infused with social praxis and signification.

There is no necessary one-to-one relationship

between the science and social science.

However, an interesting development

within RS has been to use methods ofimage

classification that incorporate geographical

thinking. Standard methods ofclassification

generally are probability based (and Bayesian,

notably the maximum likelihood approach:

seebayesian analysis). If it is known (from

direct evidence) where various land cover

types are located on some parts of the RS

image, then it is possible to extrapolate and

determine that the spectral signatures of

other parts of the image more likely indicate

one land cover type than any other. A more

geographical approach is to classify pixels

within the context of what is around them; to

extract information about spatial configur-

ations and associations that may say more

about the land function than an aspatial ana-

lysis of land cover alone. Such techniques

include space syntax (related to graph

theory). rh

Suggested reading

Campbell (2002); Hillier and Hanson (1989);

Lillesand, Kiefer and Chipman (2003).

rent Formally defined, rent is any payment

to afactor of productionover and above

that necessary to keep it in its present use.

While any factor of production can potentially

accrue rent it is the analysis of only one factor

• land – that dominates the discussion of rent
  withingeography. This is partly because the
  payment for land is pure rent (a consequence
  of the fact that land costs nothing to produce,
  and not the case for other factors), and partly

because land is bound to location, thus lend-

ing itself to geographical analysis.

Rent is the price of land, and because land is

differentiated by both quality and location,

each land plot will have a different rent level.

Two quite different approaches have been

deployed to explain differential land rents.

The orthodox view ofneo-classical econom-

icstreats land as any othercommodity, with

rents set by forces of supply and demand. Rent

is determined as in a giant auction, with

rational buyers and sellers of land meeting

to haggle over price. Those plots of land with

characteristics most demanded given the avail-

able supply will fetch the highest rents, and in

the process determine land use. In contrast,

marxist economicsemphasizes thepowerof

different social classes in determining rent

levels. While land characteristics play a role

in setting rent, they are always subordinate to

a set of wider social relations characterizing

capitalism around the inequality of power

and resource ownership. Without inclusion

of this larger context, no analysis of rent is

complete.

Both traditions have provided analyses of

the role of land rent within explicitly geog-

raphical settings. The von thu

..

nen model

is the best known within the neo-classical

tradition (Chisholm, 1979). Assuming that

agricultural crops are cultivated at varying

distances around a town, which is also the

sole market, a competitive bidding process

among farmers results in plots of land closer

to the town centre receiving differentially

higher rents than those farther away. In this

case, the spatial pattern of land rents is

explained by differential savings intransport

coststhat allow farmers closer to the town to

bid higher rents than farmers farther out.

Rents are thus set by the supply and demand

for plots of land differentiated by location.

The von Thu ̈nen model has also been

extended to explain rents within the city.

William Alonso’s bid-rent approach (see

alonso model) draws upon differential trans-

portation costs ofcommutingalong incomes

to explain urban land rents and residential

land-use patterns.

The Marxist approach to rent is most asso-

ciated with writings by David Harvey (1999

[1982]) and Neil Smith (2008 [1984]).

Harvey draws directly on Marx’s categories

of absolute and monopoly rent to stress the

role ofclasspower in determining rent levels.

Landowners use their clout either to restrict

investmentin the case ofabsolute rent,orto

constrain the supply of land in the case of

Gregory / The Dictionary of Human Geography 9781405132879_4_R-new Final Proof page 644 2.4.2009 9:12pm

RENT