USING SVG TO PROVIDE CUSTOMIZED HOUSING SOLUTIONS FOR LOW-INCOME POPULATION

Keywords: Architectural models , Customizing SVG documents , own land building

Prof. Germán Enrique BRAVO-CÓRDOBA
Associated Professor
Universidad de los Andes, Departamento de Ingeniería de Sistemas y Computación
Bogotá
Colombia
gbravo@uniandes.edu.co

Biography

Computing and Systems engineer from Universidad de Los Andes, Bogota, Colombia; DEA Informatique from the Institute Nationale Polytechnique de Toulouse, France. Associated professor in the Computing and System Engineering Department at Universidad de Los Andes since 1989. The main areas of interest concern information engineering and programming, mainly geographic information systems, databases and grid computing. Responsible of the Computing Laboratories at the Department since 2001.

Dr. Claudia Lucía JIMÉNEZ-GUARIN
Associated Professor
Universidad de los Andes, Departamento de Ingeniería de Sistemas y Computación
Bogotá
Colombia
cjimenez@uniandes.edu.co

Biography

Computing and systems engineer form Universidad de Los Andes, Bogotá; DEA and Docteur en Informatique, from INP, Grenoble, France. Associated professor in the Computing and System Engineering at Universidad de Los Andes from 1989. The research and courses work are in the information engineering area, mainly databases, document management, multimedia information management, XML and SVG information integration and datagrid computing. she works in the undergraduate, magister and other postgraduate programs, as well as research projects.

Mr. Rafael Armando GARCIA-GÓMEZ
Academic Director
Politécnico Grancolombiano, Departamento de Ingeniería de Sistemas
Adjunct professor
Universidad de los Andes, Departamento de Ingeniería de Sistemas y Computación
Bogotá
Colombia
rgarcia@poligran.edu.co
rgarcia@uniandes.edu.co

Biography

Computing and systems engineer form Universidad de Los Andes, Bogotá; Magister in mathematics from Universidad Nacional de Colombia, Bogotá. Instructor professor in the Computing and System Engineering at Universidad de Los Andes until 2006, currently adjunct Professor at this University. Academic Director of the Systems Department at Politécnico Grancolombiano. Academic Director of the Mathematics Department at Politécnico Grancolombiano. The main research and courses work are formal methods for software construction, computable analysis (TTE), numeric methods, language theory and bioinformatics.

Mr. Sergio Daniel MORENO-PUENTES
Research Assistent, Adjunct professor
Universidad de los Andes, Departamento de Ingeniería de Sistemas y Computación
Bogotá
Colombia
serg-mor@uniandes.edu.co

Biography

Born November 8th 1983, graduated in Systems Engineering from Universidad de los Andes, Colombia in 2007. Currently research assistant for project Cumbia. (http://cumbia.uniandes.edu.co).


Abstract


This paper presents CatArSis, a successful project using SVG as representation and integration technology for architectural information. The project’s objective is the development of a systematized catalog of home solutions for low-income population, assuring architectural quality, appropriate technical conditions and satisfying all legal issues in Bogotá, Colombia. SVG has been chosen as the basic representation for architectural information, in order to generate customized documentation appropriate to demand building licenses and to apply to government subsidies. The paper presents the problems issued from the own-land-building and then the architectural and computational solution developed, making emphasis in the use of SVG technology in the system.


Table of Contents


1. Introduction
2. General Context
     2.1 The own-land-building phenomenon
     2.2 Legal context: Urban norms and the building licenses
3. The CatArSis’ Strategie
4. CatArSis: An Architectural and a Software Solution
     4.1 The architectural solution
     4.2 The software solution
     4.3 Main users and operations
     4.4 Software Architecture of CatArSis
          4.4.1 Architectural models management module
          4.4.2 Beneficiaries’ management module
          4.4.3 Budget management module
          4.4.4 Development environment
5. Using SVG in CatArSis
     5.1 Geometric component
     5.2 Architectural models customization component
     5.3 Interface and visualization component
     5.4 Document generation and customization component
6. Results, Conclusions and Future Work
Bibliography
Acknowledgements
Footnotes

1. Introduction

The ordered urban development of a city is a difficult issue when people do not, or can not, follow all technical specifications of the building projects they do. This is the case of low-income population, who hardly acquires a plot for their house, but rarely can afford the costs of legal, architectural and engineering studies, in order to construct it correctly. A phenomenon called “own-land-building" occurs, which implies problems of informality, the constructions do not follow the minimal technical specifications and the lack of homogeneity in the constructions, even in the same block.

Legal construction implies that the project has been approved and has the corresponding building license. City government, by granting subsidies, promotes legal construction among low-income population by means of an institution called Caja de Vivienda Popular (CVP). Currently, the getting of a building license is long and costly, because it implies, among others, the honoraries of professionals and the costs of study the construction project to verify whether it follows the urban norm or not.

In order to reduce theses costs and facilitate the getting of the building license for their house, and hence the corresponding subside, to low-income population, Los Andes University have developed CatArSis to provide building solutions for social purposes. CatArSis has an architectural component providing appropriate home solutions for low-income population – a set of complete and high quality architectural models, almost ready to be approved – and a software component that stores them, permits the choice of one of them and finally prints the corresponding model documentation, fully personalized, as required to get the building license. This paper describes these two components, making emphasis in the software one, and specially, in the use of SVG as a representation format for the architectural information.

For the software component, the main functional requirement is the customization of models, in order to generate the personalized documentation. To fulfill this requirement SVG was chosen as the representation format for architectural information. The models are drawn, converted to SVG and then imported to CatArSis. When a model is chosen, the customization information (addresses, names, location, etc.) is appended to SVG files and then printed. Non-functional requirements include the easy and low cost of the implementation, and the usability of the system. The first one is guaranteed by the use of free licensing software tools and standard technology, and by defining that all printed information goes in legal size sheets of paper; a web browser as the front end satisfies the second one. In this way, neither, CVP or its beneficiaries have to incur in additional costs to implement or use CatArSis.

This paper presents first the own-land-building problem and the CatArSis’ strategy to deal with; then, it describes the architectural and software solutions proposed, making emphasis in the use of SVG; and finally, synthesizes the results, gets some conclusions and defines some future work to do.

2. General Context

2.1 The own-land-building phenomenon

Bogotá has 6'776.009 million habitants [ref1], corresponding to 16.4% of Colombian population, living in about 2 million homes [ref3] [ref4]; about 70% of them (nearly 5.56 millions of habitants) correspond to low-income population, having 32.8% of the overall city income, earned mainly for labor activities [1]. Upon statistics [ref3] , in last quarterly 2005, in Bogotá and for this population sector, 3833 building projects were finished, and 11613 were under construction. In the first quarter 2006 [ref2], 10245 new building projects where reported in Bogotá, corresponding to 61.25% of the whole country; 32.61% of these new buildings are housing for low incoming families. This data show the great dynamics in building for this socio-economic group.

An important phenomenon in this social context is the called “own-land-building" : Families acquire a plot, in order to build their houses in the future, when resources are available. In general, the building is owner’s responsibility and, in many cases, performed by self-construction. One of the main characteristics of this kind of construction is the informality: It is usual to build the house by stages, without greater technical planning of engineering or architecture, and little care of city-planning norms regarding the height of the house, road allocations and minimum living areas, among others. It is also usual to find real estates with license for a certain number of floors but that, in fact have more, because the owner adds additional floors as time passes, with the evident risks by the lack of foundations, resistance to seismic events, land stability, flooding, etc. Another consequence is that there is no uniformity in the houses in a block, nor the neighborhood, as can be observed in the urbanizing building projects.

In conclusion, this phenomenon must be controlled and must be then one of the main concerns of governmental institutions, in order to have an ordered and less risky city.

2.2 Legal context: Urban norms and the building licenses

In Bogotá, there are three institutions mainly concerned by the ordered development of the city:

Within this institutional context, the process when a low-income person wants to legally build his house is: First, the owner needs to contract an engineer or an architect and demand him to design a house for his plot, fulfilling all city-planning and technical norms and generate the corresponding documentation. Then, he tries to obtain the building license; he must present the corresponding documentation as many times as necessary, until all urban norms are satisfied. With the building license, he demands the CVP for the VIS subsidy. Finally, he may contract a constructor or builds the house by his own. Low-income population can hardly afford the costs associated to this process. These costs include the honoraries of professionals and each study of the documentation.

In conclusion, in order to reduce the informal construction in the city, it is necessary to reduce the costs associated to getting a building license and the time required to complete the whole process.

3. The CatArSis’ Strategie

To accomplish this objective, CVP and Los Andes University have signed a cooperation accord. The research groups GIV (Grupo de Investigación en Vivienda) from the Architecture Department and COMIT (Communications and Information Technologies) from the Systems and Computation Department worked together to define and implement CatArSis, by its name in Spanish “Catálogo Arquitectónico Sistematizado" to reduce the costs of getting the building license for own-land-construction.

CatArSis proposes to generate a set of generic architectural models, based on the desired characteristics of VIS construction projects and then socialize them, in order to be widely used in the city.

The proposed models have the following features:

Concerning the socialization, the models must be known by the CVP, facilitating their dissemination among the objective people, by the “curadurías", who may easily approve construction projects using them, by the low-income population by the way of CVP, and finally by the construction companies that can propose lower construction costs based in the volume of projects. In order to get to all these people, a software tool stores the models, makes queries over them to find the most appropriate to a given owner and plot, and, when required, print all the model documentation, fully personalized, as required by the “curadurías"

With the models developed and the software tool available, CatArSis redefines the process for own-land-building, as follows:

The estimated impact of this project for the user is to reduce the whole process time to 50%, and the related costs to 10%. For the city, there will be a great improvement in its development, having a better ordered city, less informal building, lower risks and reduced management costs.

4. CatArSis: An Architectural and a Software Solution

The main purpose of this project is then to generate a set of generic architectural models fitting the needs of “own-land-building" phenomenon and to construct a software application supporting its management and querying. This section presents first the architectonic solution and then the developed software solution. The legal component is responsibility of CVP and is out of the scope of this article.

4.1 The architectural solution

The proposed models are based on the usual geometry of objective plots. According to statistical information, the “own land" plots (about 30,000 in Bogotá) are usually rectangular, varying between 4.7 and 6 m. in front and between 10.5 and 12 m. in depth. For this first exercise, based on the financial capacity of objective population and building tradition in Bogotá, the models are based on construction bricks N° 5, measuring 33 x 17.5 x 11.5 cm, and a modulation unit of half a brick is taken.

The parameters to design the models are:

The following factors are also taken into account:

According to these parameters and restrictions, a set of families of high quality architectural models is defined. All models in a family have the same typology, expected use, topography, spaces in the front and location in the block; they differ only in their dimensions. CatArSis allows as many building technologies and model families as necessary. For this first stage of the project, seven families have been developed and 85 models have been designed and fully documented.

4.2 The software solution

The software solution effectively supports the storage and querying of architectural models, the generation of model documentation and tracks the users and models chosen in order to have some degree of accountability about the use and effectiveness of CatArSis.

The information to manage concerns the architectural models, the users demanding them and materials costs, allowing the calculus of the actual cost to build the house at any moment.

Two other issues have been considered: the easy and low cost of the implementation of CatArSis in one or several sites of CVP and the usability of the system. The first one is guaranteed by the use of free licensing software tools and standard technology and the second one by choosing a web browser as front end for the system.

It is a real issue of CatArSis the fact that it is not limited to technologies, typologies, dimensions and other parameters above. By the definition and implementation of a formal grammar describing the models, CatArSis is able to accept models for whatever architectural application domain.

4.3 Main users and operations

CatArSis has three main user categories:

4.4 Software Architecture of CatArSis

Figure 1 shows the architecture of CatArSis. This section presents a brief description of general modules. The modules concerning directly to SVG are presented in more detail in section 5.

4.4.1 Architectural models management module

This module manages the architectural models database. The content of this database represents the universe of solutions proposed by CatArSis, describing all their characteristics: dimensions, construction technology and the others specified earlier in this article. This module manages the model parameters in a generic way and can accept models appropriates to other architectural domains without any problem

To populate this database, there are naming and development conventions that must be followed by architects when they design a model, such that CatArSis can recognize and include the model in its universe of models. The database contains references to a repository with all files representing the model documentation. This repository tends to be huge.

4.4.2 Beneficiaries’ management module

This module manages the beneficiaries of CVP database: the people coming to CVP searching for a housing solution for their plot and the corresponding subsidy. This module keeps track of users, plots, proposed models, chosen models, dates of all operations and subsidies granted. With this information, CVP can monitor the use and effectiveness of CatArSis, preferred models, usual plots, etc.

./fig1.jpg

Figure 1: Software architecture diagram

4.4.3 Budget management module

This module manages all information concerning materials, quantities and costs to guarantee an up to date calculation of budget necessary to build a model. For a given technology, the information managed is the needed materials and their unitary cost; for a model the required quantities of materials.

This module has two main operations: The generation of a standard budget document for any model and the updating of unitary costs database.

4.4.4 Development environment

CatArSis has been developed in Windows platform having a web browser as front end. It has been designed as a multi-tier application, although for this first version it is working as a standalone application. The main reasons for these decisions are that connectivity cannot be guaranteed in all CVP’s offices, that CVP wanted to use the existing infrastructure and that a short learning curve for CVP’s operatives was desired.

CatArSis has been developed in Java 1.5, using SVG and Batik [ref5] to manage the architectural documentation and customizing, and Postgres [ref6]as DBMS.

5. Using SVG in CatArSis

The main purpose of CatArSis is the generation of documents allowing the user to demand a building license and become creditor to the subsidy given by government.

Although the models are generic, the main issue is that documentation must correspond exactly to the reality, respecting the plot, its location and address, its form and dimensions and to the user information. The legend of each generated document - plans, budgets - must include the location of the lot, its address, the name and identification number of the user, and eventually the name and identification of the constructor. Concerning the plans, the model must fit the plot, streets must be correctly labeled, dimensioning between plot and model have to be calculated and included, the plot area not covered by the model is hatched, etc.

This information is only known when a person arrives at the CVP looking for a solution house for his/her plot: The automatic manipulation of documents associated to the models including the architectonic plans is then necessary.

SVG has been chosen as the representation format for all model documents, by the following three reasons: independence of commercial tools, usability of the system in order to use a web browser for visualization, and finally by the possibility to edit the architectural models in order to satisfy legal requirements. For model generation, architects can use whatever tool they have, but to include the model in CatArSis database, they translate them to SVG. For this particular project, models were initially designed in AutoCad®.

Figure 2 shows an example of the visualization of the first floor plan of a model, with all customization specified. The deformation of the plot and how the model is correctly located within the plot, can be appreciated; there is also the inclusion of the address in the plane (KR 13 A, to the right), the dimensions of the plot and the differences with dimensions of the model (to the left and to the top). The legend has all the user and his/her plot information. Figure 3 shows a section plan, having also the corresponding customization.

./fig2.jpg

Figure 2: First floor customized plan

The fundamental strategy to obtain these results was the early definition of legend contents and layout, considering the restriction to print all documentation in legal size sheets of paper. The orientation of the model is defined, by placing the front of the model always to the right of the sheet of paper.

./fig3.jpg

Figure 3: A Section plan showing the SVG customized legend

The template information (see Figure 4) defines the areas where information has to be placed. The bottom part contains the legend; the central part for the maximum plot and inside it the architectural model; the right side is for address and road allocation restrictions; around the plot the dimensioning of the plot; on the top, the dimensioning of the model and finally to the left there is an area to place other information if needed. Some of these areas are available only for architects while other is reserved to CatArSis.

This template was defined in SVG and understood by CatArSis to locate correctly the models and make the corresponding customization for the screen and for the printed version.

The following sections describe in detail the components of CatArSis (see Figure 1), directly related to SVG, satisfying the requirements and issues described throughout this paper.

5.1 Geometric component

This component attempts to solve the geometrical problem associated with the selection of architectural models appropriated to a particular plot.

./fig4.jpg

Figure 4: Template for architecture design and SVG software edition

An instance for the geometric problem includes a set of models A={M1,…,Mn}, a plot L and a set of tolerance or over measure values ε. Each model in the set A is described by the 4-tuple Mk=(fk,bk,mk,lk), where (fk,bk) denotes the dimensions of the sides in the rectangle associated to the ground floor plan of the model, mk denotes the size of the unitary component, and lk ∈ {D,M,I} represents the location of the model in the block of houses. A plot is described by the 6-tuple L = (p1,p2,p3,p4,l,a), where pi=(xi, yi) represents the absolute location of each corner of the plot. This absolute location is related to the origin of coordinate system of the city, l ∈ {D,M,I} represents the location of the plot in the block of houses, and a is a set of affectations used in order to calculate the actual usable dimensions of the plot. Note that the plot L is not necessarily a rectangle.

The solution to a particular instance of the problem is a ordered set S ⊆ A such that, if M ∈ S then M is a model suitable for the plot L. M can be built in the plot L whenever M respects location (l), road allocation (a) and has gap values less than tolerance values (ε). S is decreasingly sorted, with the relation order given by a function providing a goodness measure of the model – plot ratio.

Obviously, the algorithm in the first phase apply a filter on the set A to obtain a set A1 such that, if Mk ∈ A1 then lk=l and area(L) - Earea(ε,mk) ≤ fk * bk ≤ area(L). In other words, select all models from A such that the location in the block of houses is the same that the location in the block of houses of the plot, that can be built in the plot and respect the area tolerance value (the area tolerance value is function in ε and mk).

In a second phase, all models in A1 are collocated, performing modular rotations and modular translations, inside the plot L. This location provides a measure to the model – plot relation: c(Mk,L). The value c(Mk,L) is used to sorting the solution set S. S contains only models in A1 with a good qualification for the model – plot ratio.

5.2 Architectural models customization component

This component is charged of the SVG manipulation of vector information, in order to customize applicable models documentation to a particular plot. It constitutes one of the main aspects of this work.

The main challenge of this component lies in the spatial integration of model information and the actual user and plot information. This integration must be done in the plans, specifically with respect to the location of the model in the plot and in the block of houses, the road information and in the plan legend.

The customization information is entered to the system when a user demands CVP for a house solution. Based on the defined template, this module inserts this information in the appropriate places of the SVG document.

5.3 Interface and visualization component

Obviously, this component deals with the interaction between users and CatArSis. It is charged of visualization of SVG vector information, display manipulation, navigation over the models documentation and receives the events triggering the functionalities of the system. Figure 5 shows the interface presented to CVP’s operatives, divided in three sections.

./fig5.jpg

Figure 5: CatArSis interface

The upper part of the screen contains the zone to navigate over pre-selected models and plans. It has two rows of tabs: Tabs in the upper row corresponds to pre-selected models; tabs in the second rows correspond to model documents. At first instance, for all suitable models for a plot, CatArSis presents the first two floor plans of each model, expecting that this is enough information for the owner to choose the model he wants.

The central zone of the screen shows the vector information of the model, already located in the beneficiary’s plot and the corresponding customization. This is information in SVG format and respects the aspect ratio of the printed information. Alphanumeric information concerning detailed use of areas and budget is also generated in SVG and shown in this pane. Zooming and panning using the keyboard are available, based on Batik’s features. The bottom of the screen contains the data entry panel (see Figure 6). The layout is organized by categories: owner identification, plot information (cadastral information, location and urban norm), optional information about the constructor and finally some command buttons.

Menu options complete the functionality of the system, allowing the initialization of databases, the updating of costs database, and finally the impression of model documentation.

./fig6.jpg

Figure 6: Data entry screen

5.4 Document generation and customization component

This component solves the associated problems to the generation and printing of architectural model documentation. This printed information is the final result of CatArSis towards the potential beneficiaries of the own land building solutions. The printed model documentation includes CVP’s technical presentation, construction manual, complete set of plans, tables of areas of the project and its detailed budget.

The main challenge of this component lies in the manipulation SVG file in order to adapt SVG information to the specific paper format, preserving the aspect ratio in all plans. SVG is a vector format of images and then scalable in natural way: the scale and proportions of visualization and impression depends on the way the user use the web browser, generating eventually deformations in the plans. The printing and the visualization modules manage this situation in order to avoid these deformations dues to factors outside the control of CatArSis.

Another interesting challenge is the printing of SVG files preserving the detail of the architectonic drawing in such a way that the thickness of lines, labels and dimensioning respect the architectonic conventions.

6. Results, Conclusions and Future Work

This article presents the successfully use of SVG in customizing technical and architecture information, in the context of own land building solutions for low-income families.

The choosing of SVG as the format to represent architectural information was one of the keys of this success. Customized documents are generated and neither, CVP or its beneficiaries have to incur in additional costs. CatArSis runs over standard infrastructure (Windows, web browser, java, SVG …) and uses the printing facilities provided by Windows, and then, it is not necessary to buy additional hardware or software. The use of a web browser as front end diminishes the learning curve of the system. CatArSis can easily be implemented in various places and environments. From social point of view, there is a considerable reduction of costs and time in the whole process of obtaining a building license and build the house. From the point of city, it will become more ordered and administrable.

Some issues concerning SVG had to be solved. Some of them are the definition of standards for legends and model generation, the modifications to SVG files to reflect the required customization, the finding of best fitting location of a model within a plot and the preservation of the aspect ratio of architectural information.

The project has been presented to several institutions concerning city planning, real state registration, city development, financial aids in social projects, among others, and has been fully accepted by them. It is expected that they define cooperation protocols in order to increase the effectiveness of CatArSis and architectural models developed.

The future of CatArSis glimpses in several fronts, mentioned here without any particular order: To achieve a greater dissemination of the software, using it in other municipalities. To increase the building models database, including, by example, three floor houses or other building technologies. To produce building solutions for other social building purposes, other than housing, like hospitals and schools. To produce models with other geometric features, allowing architectural modifications made by the software on query time and not on the building time as stated until now. Finally, the integration of CatArSis with other government applications, in order to provide on line verification of urban norms, plot registration, owners, grants verifications, etc.

Bibliography

[ref1]
Dane, Departamento Nacional de Estadística de Colombia. "Census 2005 report". 2005. http://www.dane.gov.co
[ref2]
Dane, Departamento Nacional de Estadística de Colombia. “Vivienda VIS y No VIS - I Trimestre de 2006". 2006. http://www.dane.gov.co/files/investigaciones/boletines/vis/bolet_vis_Itrim2006.pdf
[ref3]
RCN. “En Bogotá, el ingreso de los ricos es 49 veces mayor al de los pobres". Jun 2006. http://www.rcn.com.co/noticia.php3?nt=14035
[ref4]
Secretaría de Hacienda Distrital. “Ingresos, gastos y exclusión social en Bogotá". Cuadernos de la ciudad – Serie Equidad y Bienestar. N° 8. March 2006 http://www.shd.gov.co/pls/portal/docs/PAGE/PORTAL_INTERNET/PUBLICACIONES/TAB_ECO/TAB340482/TAB340498/E_Y_B_9_8_EXCL_SOCIAL.PDF
[ref5]
Batik Project. Jun 2006. http://xmlgraphics.apache.org/batik/
[ref6]
Postgres Project. Jun 2006. http://www.postgresql.org/

Acknowledgements

Authors want to thank the essential work of the architect team of the project: Rodrigo Rubio, Rafael Villazón, Juan Pablo Cuervo, Javier Silva, and Camilo Olano. Their work in the model conception, plan design and technical information production for CatArSis is remarkable. We thanks Architect Rodrigo Rubio for involve us in this important project for the development of our city.

Footnotes

  1. Complete data from the census 2005, on building and population in Colombia, may be consulted in [ref1].

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