Ramesh Krishnamurti

The ASDMCon Project: The Challenge of Detecting Defects on Construction Sites

Techniques for three dimensional (3D) imaging and analysis of as-built conditions of buildings are gaining acceptance in the architecture, engineering, and construction (AEC) community. Early detection of defects on construction sites is one domain where these techniques have the potential to revolutionize an industry, since construction defects can consume a significant portion of a projects budget. The ASDMCon project is developing methods to aid site managers in detecting and managing construction defects using 3D imaging and other advanced sensor technologies. This paper presents an overview of the project, its 4D visualization environment, and the 3D segmentation and recognition strategies that are being employed to automate defect detection.

Explicit design space

This paper examines the need for explicit representations of the design space, in response to Woodbury and Burrow. Specifically, their proposal for a particular search strategy, by means of which one can reuse past experiences explicitly represented by previously traversed paths, is examined. This is done by exploring issues with respect to design search and representation in general, while relating these to specific issues raised by Woodbury and Burrow. The paper concludes by suggesting that their arguments essentially point to devising an appropriate “programming language” for design.

SORTS: A CONCEPT FOR REPRESENTATIONAL FLEXIBILITY

This work is based on the recognition that there will always be a need for different representations of the same entity, albeit a building or building part, a shape or other complex attribute. This exigency ensues, formally, to define the relations between alternative representations, in order to support translation and identify where exact translation is possible, and to define coverage of different representations. We consider an abstraction of representations to model sorts that allows us to define algebraic operations on sorts and recognize algebraic relationships between sorts, providing us with a method for the analysis of representations, and the comparison of thencoverage. We present the basis of support for a multi-representational environment.

Representational Flexibility for Design

We present an abstraction of representational schema to model sorts that allows us to explore the mathematical properties of a constructive approach to sorts We apply this approach to representational schema defined as compositions of primitive data types, and explore a comparison of representational structures with respect to scope and coverage. We consider a behavioral specification for sorts in order to empower these representational structures to support design activities effectively. We provide an example of the use of sorts to represent alternative views to a design problem. We conclude with a comparison with other approaches for flexibility of design representations.

Construction process simulation with rule-based robot path planning

A rule-based simulation program is developed for application to building construction. From a specified task schedule, the program generates and simulates a motion path for each robot action, avoiding obstacles and incorporating interaction, safety and other considerations.

Tractable Shape Grammars

In this paper we explore the theoretical basis for a concept of ‘computation-friendly’ shape grammars, through a formal examination of tractability of the grammar formalism. Although a variety of shape grammar definitions have evolved over time, it is possible to unify these to be backwards compatible. Under this unified definition, a shape grammar can be constructed to simulate any Turing machine from which it follows that: A shape grammar may not halt; its language space can be exponentially large; and in general, its membership problem is unsolvable. Moreover, parametric subshape recognition is shown to be NP. This implies that it is unlikely, in general, to find a polynomial-time algorithm to interpret parametric shape grammars, and that more pragmatic approaches need to be sought. Factors that influence the tractability of shape grammars are identified and discussed.

A Paradigm for Interpreting Tractable Shape Grammars

Shape grammars are, in general, intractable. Even amongst tractable shape grammars, their characteristics vary significantly. This paper describes a paradigm for practical general shape grammar interpreters, which aim to address computational difficulties posed by parameterization. The paradigm is expressed in terms of frameworks each comprising an underlying data structure, manipulation algorithms, and a metalanguage. The approach is illustrated through three exemplar frameworks.

Algorithms for classifying and constructing the boundary of a shape

This paper continues with the subject matter that we introduced previously (Krishnamurti and Stouffs, 2004). Here, we describe algorithms for classifying the boundary of a shape with respect to another, coequal, shape and for constructing the description of a shape given parts of the boundary that make up the shape. Specifically, algorithms for classification and construction of shapes in U23 (plane shapes) and in U33 (volume shapes) are described in this paper. These procedures form a unified basis for shape arithmetic.

Data Views, Data Recognition, Design Queries and Design Rules

Sorts present a constructive approach to representational structures and provide a uniform approach to handling various design data. In this way, sorts offer support for multiple, alternative data views and for data exchange between these views. The representation of sorts extends on a maximal element representation for shapes that Supports shape recognition and shape rules. In the same way, sorts offer support for data recognition, for querying design information and for expressing design rules. In this paper, we present an overview of the use of sorts to support these functionalities. Each of these relies on the ability to alter representational structures or sorts, and to manipulate the composition of data forms. In this regard, we briefly consider the user interaction aspect of utilizing sorts.

Integration of knowledge-based and generative systems for building characterization and prediction

Abstract This paper discusses the integration of knowledge bases and shape grammars for the generation of building models, covering interaction, system, and implementation. Knowledge-based and generative systems are combined to construct a method for characterizing existing buildings, in particular, their interior layouts based on exterior features and certain other parameters such as location and real dimensions. The knowledge-based model contains information about spatial use, organization, elements, and contextual information, with the shape grammar principally containing style rules. Buildings are analyzed and layouts are generated through communication and interaction between these two systems. The benefit of using an interactive system is that the complementary properties of the two schemes are employed to strengthen the overall process. Ontologies capture knowledge relating to architectural design principles, building anatomy, structure, and systems. Shape grammar rules embody change through geometric manipulation and transformation. Existing buildings are analyzed using this approach, and three-dimensional models are automatically generated. Two particular building types, the vernacular rowhouse and high-rise apartment building, both from Baltimore, Maryland, are presented to illustrate the process and for comparing the utilized methodologies.