Sixth International Workshop on Geographical Analysis...
Transcript of Sixth International Workshop on Geographical Analysis...
Sixth International Workshop on "Geographical Analysis,
Urban Modeling, Spatial Statistics"
GEOG-AN-MOD 11 in conjunction with
The 2011 International Conference on Computational
Science and its Applications (ICCSA 2011)
June 20 th to June 23 th, 2011,
University of Cantabria, Santander, Spain
Pier Luigi Paolillo(1),
with Alberto Benedetti, Umberto Baresi, Luca Terlizzi, Giorgio Graj
(1) Politecnico di Milano
[email protected] - http://webdiap.diap.polimi.it/paolillo/
1. Why the historic centres: a
preliminar consideration
2. The methodological process:
from the selection of descriptor and
variables to the final synthesis in the
“suitability for change” map
3. Method for analysing and
assessing the characteristics of
centrality and socioeconomic
vitality
4. Assessing the values of the built
fabric
5. The final step:
the map of suitability for change
and the relative types of change for
the single built fabrics
Estimate:
(α) residential vitality
(β) commercial distribution
(γ) services accessibility
ASSUMPTION OF THE BEST SCENARIO FOR SUITABILITY FOR
CHANGE OF BUILT FABRICS
Results:
Socio/economic
characterization
5 scenarios derived from “f”
function
Regional
Laws
Support to
administration
Identify types of change
in built fabrics
(art. 27 Lr.12/05)
Classify priority of
intervent in historic
centre
Goal:
Define degrees of suitability for change
of single buildings
Goal:
Identify and quantify demographic,
economic, social tendency
Suitability for change Social and economic phenomena
Database organised to develop Gis analysis
Multi/dimensional analysis
Comparison between scenarios and socio/economic aspects, and selection of the best-one
),,,,,( FEDCBAf
Use an algorithm to create
scenarios of suitability for change
0. The framework assumed
Urban Planning Discussion-ANCSA:
Growing importance (since 50’s) of “historic
centres” issue, related today with a
generalised decay:
- RELATIONAL (population and vacancy)
- STRUCTURAL (appeal and economy)
- PHYSICAL (built fabrics)
1. Why the historic centres: a preliminar consideration
REGULATION assessment in LOMBARDY:
- LR.12/2005: NEW PLANNING
INSTRUMENT, PGT
Goals:
- identify HISTORIC CENTRES
- recognize Types of change for each
fabric
Structuring the method:
Necessity of a different approach based on quantitative analysis
Preliminar analysis of the case-study: territorial phenomena and
planning instruments;
Use of the database to develop analysis and evaluations with Gis
software
Como historic centre:
Worsening in terms of:
- weakness in human relations
- lost of attractivity
- Growing decline and vacancy
in built fabrics
Change of approach:
60’s * conservation of historic fabrics
Today * re-use of built fabrics, in order to:
- not use further free-soil
- use fabric nowadays vacant
Identifying the
variables
Grouping the variables into
summary indicesSocio/
economical aspects
Identifying the spatial units
of investigation
Historic/
architectural aspects
Multidimensional/
algorythm analysis
Areas of iso-
problematicity
Scenarios for
change
Identifying the
descriptor blocks
Selecting the most
suitable scenario for
change in this specific place
Spatialising the phenomena
(thematic mapping)
2. The methodological process: from the selection of descriptor and
variables to the final synthesis in the “suitability for change” map
3. Method for analysing and assessing the characteristics of centrality
and socioeconomic vitality
Function
indicating how various phenomenical
aspects flow together
into the socio/economical analysis
where:
A = tendency to accumulated centrality of
the historic centre;
B = instability of the fabric due to
monofunctionality;
C = density of localisation of the most
strongly attractive activities;
D = stability of the inter-relating residential
fabric;
E = urban landscape importance of
buildings
Innovative tools and applications
Multiple centrality assessment
- Porta et al., 2006; Cardillo et al., 2006;
Crucitti et al., 2006; Scellato et al., 2006
- Similar approach to configurational
analysis (Bill Hillier and the UC London
school)
- Moving from space configuration to recognize
structure and caracteristics of open urban
spaces
Viewshed
- Viewshed analyses: common function of
most Gis software. The analysis uses the
elevation value of each cell of the Dem to
determine visibility to or from a particular cell
- Application of viewshed to built fabric with
specific carachteristics (constraints, facades,
uniformity of a specific built-area)
3. Method for analysing and assessing the characteristics of centrality
and socioeconomic vitality
Indices and variables
A) Mca (Multiple centrality
assessment)
Goal:
recognize the inclination towards
transformation of built fabrics
Indices:
Betweenness -> traffic long-radius
Local closeness -> traffic short-radius
Land use density -> concentration of
extra-residential buildings
Functional heterogeneity -> application of
Shannon index to calculate heterogeneity
Basis:
- Connection
from point to
point to create
Axial map
(ecuclidean
axis) with Mca
tools
Betweenness (x) Local
closeness (y)
Network
interaction (a1)
2
yx
Land use
density (x)
Functional
heterogeneity (y)
Vitality of the
economic fabric
(a2)
2
yx
3. Method for analysing and assessing the characteristics of centrality
and socioeconomic vitality
Indices and variables
B) Instability of the fabric due to
monofunctionality
Goal:
Recognize areas with potential risk of
becoming monofuncional and central
“banlieue”
Indices:
Index of ageing -> areas with old
inhabitants
Residential density -> areas with
inhabitants
Index of heterogeneity of non-residential
activities -> monofuncional areas
Basis:
- Make residential
and economical
data interacting
toghether using
Kernel Density
Index of ageing Residential density
Index of
heterogeneity
of non-
residential
activities
Thematic activities
3. Method for analysing and assessing the characteristics of centrality
and socioeconomic vitality
Indices and variables
C) Density of localisation of the
most strongly attractive activities
Goal:
Recognize the competitive areas from
the economic point of view
Indices:
Density of commercial activities
Density of service sector activities
Density of
commercial
activities
D) Stability of the inter-relating
residential fabric
Goal:
Recognize problematic residential areas
Indices:
Incidence of the non-Italian resident
population
Incidence of residential vacancy
Distribution of the population within
buildings (underoccupation –
overcrowding)
Density of
service sector
activities
Vacancy
Indices
Variables
Resident
nationality
Residential
buildings size
Roots
Census of
built fabric
Residential
dataset
Census of
built fabric
3. Method for analysing and assessing the characteristics of centrality
and socioeconomic vitality
Indices and variables
E) Urban landscape importance
of buildings
Goal:
Recognize buildings with particular
landscape values
Indices:
Building perception -> is the building
seen from relevant points of observation?
Characterisation of the perception -> how
is the building perception?
Basis:
- Advanced applications in Gis softwares:
* building the (Digital Elevation Model);
* selecting points of observations;
* building Viewshed
Building DEM
(DTM+Built fabrics)
Building
VIEWSHED
Points of
observation
Fabrics
with
positive
elements
Fabrics
with
negative
elements
Quantity
of fabric
percepted
Urban
landscape
importance
of buildings
3. Method for analysing and assessing the characteristics of centrality
and socioeconomic vitality
Viewshed procedure
Decomposing the observation
points into a number of different
viewshed analyses
(e.g.: access points to the historic
centre, busiest historic streets,
open spaces for public socialising,
and so on)
Selecting
observation
points
Sifting
informational
strata
Summarising, referring as
necessary to the qualitative
characterisation of the
particular building (E)
Quantifying and
summarising the
degree of
visibility of any
given building
Refining the analysis as appropriate (e.g.:
distinguishing between buildings seen in
perspective and buildings seen in the
round)
Analysis:
if k = 1
the building is
visible
3. Method for analysing and assessing the characteristics of centrality
and socioeconomic vitality
Applied multidimensional geostatistic analysis
i) correlational analysis, aimed at
reducing the number of variables to be
tested and used in the subsequent
stages;
ii) non-hierarchical analysis, which makes
it possible to identify the spaces that are
homogeneous in terms of the variables
adopted for describing the model
From variables and indices to
Multidimensional analysis
Use of dedicated software Addawin (prof.
Griguolo, IUAV of Venice) in the GIS
environment:
from aggregated indicators derived
estimating f (A, B, C, D, E),
to application of geostatistics procedures, in
particular multivariate analysis:
Facplan image:
step that analyses the distribution of the
centres of the stable profiles with respect
to the two axes that most effectively
explain the multivariate situation under
investigation
Phenomena
Clusters
4. Assessing the values of the built fabric
Function
indicating how various phenomenical
aspects flow together
into the built fabrics analysis
where:
F = suitability for retention, intrinsic in the
building itself
G = suitability for retention, in the
relationship between building and urban
blockH = the urban landscape importance of the
context in which the building stands
I = suitability for increases in volume
Assumption of descriptors block and variables
Indices and variables
F) Suitability for retention,
intrinsic in the building
Goal:
recognize the inclination towards
transformation of built fabrics
Indices/variables:
F1 - presence of environmental and
historic/architectural constraints
F2 - persistence of buildings over time
F3 - the state of conservation of buildings
F4 - presence of facades to be retained
F5 - presence of excrescences
F1 - Contraints F2 - Datation
F3 - Conservation F4 - Facades
F5 - Excrescences
4. Assessing the values of the built fabric
Indices and variables
G) Suitability for retention, in the
relationship between building
and urban block
Goal:
recognize the inclination towards
transformation of built fabrics, in the
relation with the urban blocks
Indices/variables:
G1 - presence of transformed areas
(causing discontinuities in the urban
fabric)
G2 - degree of uniformity in respect to the
first historic threshold adopted
G3 - degree of uniformity in respect to the
number of storeys
G1 – Transformed
areas
G3 - Uniformity
(number of storeys)
G2 – Uniformity
(first historic
threshold)
4. Assessing the values of the built fabric
Indices and variables
H) Urban landscape importance
Goal:
recognize the built fabrics impact on
perception
Indices/variables:
H1 – presence of quality elements
H2 – presence of elements of contrast
H3 – index of perception of the building
H4 – incidence of the building on the
public space
H4 – Perception from public spacesH3 – Index of perception (from historic
roads, points of access, public places)
H2 – Contrast
factors
H1 – Quality
factors
4. Assessing the values of the built fabric
Indices and variables
I) Suitability for increases in
volume
Goal:
recognize the building that can be
raised as number of storeys
Indices/variables:
I1 – character of the existing built
frontage
I2 – possibility of adding extra storeys
1 – Built-front with at
least 50% fabrics with
same height
3 –Buildings useful for
raising storeys
4 –Buildings unuseful
(as reference) for
raising storeys
2 – Buildings with
specific characteristics
4. Assessing the values of the built fabric
Algorhythm for assessing suitability for change
4. Assessing the values of the built fabric
Assumption of an
algorithm to classify the
built fabrics
Classification of the result
values
Aggregation of variables
and indices in thematic
blocks
Assumption of different
classes of suitability for
change, for every built
fabrics of the historic centre
Devising the basic
algorhythm of suitability
for change
Creating
scenario 1
Types of change
permitted by the
regulations
Correlating the classes of suitability for change
to the consented methods of changes to buildings
Preparing the map of suitability for change
Devising
different
scenarios
Territorial
socioeconomicconfigurations
Comparing scenarios and selecting the scenario
that is most compatible with these territorial
configurations
4. Assessing the values of the built fabric
Building and selecting scenarios of suitability for change
4. Assessing the values of the built fabric
Classifying and
comparing different
scenario outputs
i) internal consistency:
correlation between suitability for change and the dataset
of variables adopted, identifying excessively high
interdependencies that would indicate a flattening of the
outcomes of the multivariate analysis
ii) external
consistency is the
correspondence
between the
general character of
the scenario, in
terms of suitability
for change, and the
real social,
economic, and
demographic
characteristics of
the territorial
configurations of the
historic core
Building and selecting scenarios of suitability for change
5. The final step:
the map of suitability for change and the relative types of change for the single built fabrics
Final scenario of
suitability for change Cartography
From classes to types of change on built fabrics
5. The final step:
Comparison between prescriptions of the old Prg and the new assessment recognized by Pgt
From a homogeneous
classification of buildings
To a new one, coherent
with the specific
characterization of the
single built fabrics
Previous planning instrument:
Prg -General regulator plan
(1975-1993)
New planning
instrument:
Pgt -Plan for territorial
government (2010)
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