Sixth International Workshop on "Geographical Analysis, Urban Modeling, Spatial Statistics"
GEOG-AN-MOD 11 in conjunction with
The 2011 International Conference on ComputationalScience 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) Polytechnic of [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) residenzial vitality
(β) commercial distribution(γ) services accessibility
ASSUMPTION OF THE BEST SCENARIO FOR SUITABILITY FOR CHANGE OF BUILT FABRICS
ASSUMPTION OF THE BEST SCENARIO FOR SUITABILITY FOR CHANGE OF BUILT FABRICS
Results:
Socio/economic characterizationSocio/economic characterization
5 scenarios derived from “f” function
5 scenarios derived from “f” function
Regional Laws
Support to administratio
n
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 changeSuitability for change Social and economic phenomenaSocial 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 fabricsToday * 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-radiusLocal closeness -> traffic short-radiusLand use density -> concentration of extra-residential buildingsFunctional heterogeneity -> application of Shannon index to calculate heterogeneity
Basis:- Connectionfrom point topoint to create Axial map (ecuclidean axis) with Mcatools
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 inhabitantsResidential density -> areas with inhabitantsIndex 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 populationIncidence of residential vacancyDistribution of the population within buildings (underoccupation – overcrowding)
Density of service sector
activities
Vacancy
Indices
Variables
Residentnationality
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 itselfG = suitability for retention, in the relationship between building and urban blockH = the urban landscape importance of the context in which the building standsI = 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 constraintsF2 - persistence of buildings over timeF3 - the state of conservation of buildingsF4 - presence of facades to be retainedF5 - 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 adoptedG3 - 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 elementsH2 – presence of elements of contrastH3 – index of perception of the buildingH4 – 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 frontageI2 – 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
Creatingscenario 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
socioeconomic configurations
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 datasetof 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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