In the field of Oil & Gas, the ISO15926 proposes a standard for integration, sharing, exchange and delivery of data between computer systems based on the standardization of data formats and an ontology approach to represent common industry classes and relations. Due to the structure and the large number of terms defined at this standard, the complexity of creation information models is high. This aims to consolidate a methodology for modelling geometric objects following the structure of ISO 15926. We take into account the need for complete abstraction between geometry and business data. Three approaches are presented with a comparative analysis, which should reveal the appropriate practice to be adopted both in manual and in software supported ISO15926 compliant information modeling.
using the data model [ISO 159262- 2003] and the initial refer ence data set
Due to, among others, the high complexity of modelling concepts by the structure of the standard and the large amount of terms defined by its ontology, there is no consolidated methodology for information modelling in ISO 15926. It is essential for the usability of this standard that this complexity be hidden by the template use [ISO 159267- 2011]. The most basic templates must be modelle d using only entities from ISO 15926 - Part2 and ISO 15926 - Part4 as a requirement to be co mpatible with its conceptual model. Therefore, this basic model may be specialized to accommodate any field of engineering knowledge, as geometry, whose relevance is present in any Engineering schematic, 3D model, datasheets etc.
Engineers working on Capital projects use ComputerA-ided D esign and Drafting systems (CADD), which, for representing 3D and 2D schematics, ultimately use geometric objects (or primitives), such as: ellipses, polylines etc. Thus, to interoperate geometry related information, a standard is required for the structured data that describes the geometric objects. This is offered by the ISO 15926 Part3 [ISO 159263- 2007], which defines the catalog of geometry and topology terms.
This work presents three approaches for modeling geometric objects following
ISO 15926 and a comparative analysis among them. In the next session we present a brief
introduction to this standard and after that we present our proposals. Then, we present the
conclusions, work in progress and future work.
2. ISO 15926
The ISO 15926 standard
Part 1: Overview and fundamental principles [ISO 159261- 2004] – Sp ecifies a representation of information associated with engineering, construction and operation of process plants.
Part 2: Data Model [ISO 159262- 2003] – Describes the entities used b y the standard to represent the process plant lifec-ycle information. It is d esigned to be used in conjunction with reference data [ISO 159264- 2007]: default instan ces that represent information common to users and process plants.
Part 3: Geometry and Topology [ISO 159263- 2007] – Defines objects in the reference to data library for geometry and topology. It is based on ISO 10303 [ISO 103031- 1994] and the dictionary of standard shapes are extracted from the ISO 103034-2 [ISO 103034-2 2003] and ISO 103031-04 [ISO 103031- 04 2000]. Part 4: Reference Data Library [ISO 159264- 2007] – Support for a spe cific life cycle depends on the use of appropriate reference data based on the data model [ISO 159262- 2003].
Part 6: It defines a methodology for development and validation of reference data. Part 7: Templates Implementation methods for the integration of distributed systems [ISO 159267- 2011]. A template is seen as a data schema and the part 7 describes a catalog of templates and defines an implementationi-ndepen dent template methodology for definition, verification, expansion of templates, as well as presenting an initial set of templates to allow the use of the conceptual model ISO 15926- Part2. It consists of the definition of the signature and axioms in firsto-rder logic; v erification and expansion are done with the software Template Expander.
Part 8: Implementation methods for the integration of distributed systems – OWL implementation. This part defines the specification for data exchange and lifecycle information integration using RDF and OWL to describe the templates of part7.
According to ISO15926, complex objects must be defined as templates, concepts that are defined using basic entities until they are reduced to basic terms (Proto and Core Templates). They must be compliant with ISO 15926 - Part2 and ISO 15926 - Part4, ensuring the integration of data portability and interoperability.
To define a best practice of how to represent geometry and topology of the manufactured and geological objects of an industrial process in ISO 15926, the ISO 15926 Part3 was created [ISO 159263- 2007]. It presents a huge libr ary of basic terms and definitions to be used for modeling.
According to ISO 15926, the geometric objects and properties must be
modelled using Templates
We present three approaches of modeling geometric objects, regarding a circle (geometric entity) as an example of how to use them.
In the modeling process, it is important to understand the requirements of the object that will be modelled (stage 1). At this moment we will identify the object (e.g. circle) properties according with the ISO 15926P-art3 [ISO 159263- 2007]. All the entities definitions present in this work were extracted from the ISO 15926P-art3 . Any term in boldface represents a term in the ISO 15926 ontology. Circle definition:
An object is a circle if and only if: 1i-t is curve; 2i-t lies in a plane; 3- there is a centre point that is equid-istant from each point in the cur ve. NOTE 2 A circle has the geometric properties: radius; center and plane. These properties can be given for a circle by a axial reference placement and a radius. A circle has two alternative values for the axial reference placement corresponding to opposite directions for the normal.
According with the definition, the concept circle is subclass of the concept curve and it is defined by a radius, a central point and a plane. So, the properties of a circle can be defined by the concepts radius and axial reference placement.
An object is a radius if and only if:1i-t is a function between geometric objects with a unique radius and metric space length; 2- it specifies the radius. An object is an axial reference placement if and only if: 1i-t is a function between geometric objects with a unique axial placement and axis1 placement (which is a metric space point and a direction denoted z); 2- it specifies the position and orientation of the geometric object.
The concept radius is defined by a metric space length, that stores the measure of the radius. So the concept radius is used to link the measure with an object that has a radius, at this case the circle.
By the definition, the concept axial reference placement is used to connect a plane with an object. This plane is defined by the concept axis1 placement, that is composed by a set of points (metric space point and one direction (direction). Then the concept axial reference placement will connect the axis1 placement and the circle.
After the requirements are known, it is necessary to analyze the data and the
relationships that will be used in the modeling process (stage 2) [
During the circles’ modelling process, it was observed that some concepts were not connected with each other. By the Fig. 2, only the circle is connected with the class curve, because circle is subclass of curve. In its definition, the concept radius is part of a circle, but it is not a circle (analogous to axial reference placement), so it is necessary to compound this relation. The compositions of these relations will be done with the construction of templates, whose methodology is described by the document ISO 15926 Part7 [ISO 159267- 2011]. The templates hide the internal co mplexity of the models (described by the axioms), since access is given by the elements present in the signature.
1. Definition of the signature, that describes the elements that compound the relationship; 2. Definition of Axioms/Sentences in First Order Logic (FOL), that describes the semantics through the relations between the elements presented in the signature.
The axioms will be used to verify the consistency of the template. This verification is done by a tool called Template Expander that expands the axiom until the description with concepts defined in ISO 15926P-art2 or ISO 15926P-art4 [ ISO 159267- 2011].
The specification of a template axiom in FOL is done with the if and only if logical connective, where the signature of the template is on the left side, and the sequences of formula connected with the conjunction connective are on the right side.
Example: The template RealMagnitudeOfProperty is used to connect a concept classified as a property with a numeric value and a scale (as in Table 1 and the following axiom).
What follows is a research about the template modeling process, regarding a circle as an example.The first approach presents a simplified modeling process. As some properties of the model are hidden due to its simple construction, it is necessary to understand the full model to infer these properties by queries. In the second approach, the model has more properties explicit and therefore the modeling process is more difficult it is possible to access the properties with simpler queries (it is not needed to know the full model to infer the properties in queries). The third approach proposes an intermediate abstraction between the first and the second one.
Part3, axial reference placement and radius are functions that connect concepts, so they are candidates for templates.
In this alternative, the model of the template has a low granularity, it hides some possible templates without compromising the model structure. We constructed three templates: RadiusTemplate, MetricSpacePointTemplate and DirectionTemplate. The first template will connect one object that has a radius with a value that describes the length of radius. Its signature is shown at Table 5
The concept metric space length alone does not represent the numeric value of a radius, it defines just a measure. A relationship between this measure and the circle is done by the template RadiusTemplate that relates this measure with a scale.
Some of the templates that are necessary to the modeling process can be found at the ISO 15926P-art7. In the template proposed above, the tem plates RealMagnitudeOf
15926P-art 7.
According to ISO 15926P-art3, metric space length is subclass of property. Thus, it satisfies the condition of the template RealMagnitudeOfProperty. The template RealMagnitudeOfProperty claims an scale object, defined by the ISO 15926P-art2 . The scale is used to define a range of allowed values. To model a scale the template
scale, that is connected with a numeric value and a metric space length.
The template MetricSpacePointTemplate will connect an object with a metric space point with three real values (Table 3) that defines a plane according to ISO 15926P-art3.
The template CoordinateSystem, presented at ISO15926P-ar t7, specifies a plane with its three coordinates, that are connected with the template ListOfReals3Template.
The template DirectionTemplate connect three real values to represent the direction of the object (see Table 4).
Bellow is presented a graphic example of templates instantiations (RadiusTemplate, MetricSpacePointTemplate, DirectionTemplate) to construct the circle with a radius which the value is 3, with the position(1,2,3) and the direction expressed by the coordinate (1,0,0). It uses the following diagram language. The example is in Fig. 4. All the following Figures follows the legend in Fig. 3.
high. The model is defined with five templates. As the first alternative, all the properties that define a circle are modelled. This process is more complex, but once it is modelled and instantiated, the queries about any properties will be done with ease.
The template RadiusTemplate (Table 5) is used to join all the properties about a radius. Its signature is the same as that of alternative 1, but the axiom that describes the template model is more detailed.
In the formula above, the template MappingTriple [ISO 159267- 2011] joins the object with radius to its properties.
The template AxialReferencePlacementTemplate (Table 6) defines the circles’ plane. It relates six real values: three that define the ReferencePoint and three others that defines the Direction.
AxialReferencePlacementTemplate(q,px,py, pz, dx, dy, dz) <->
ObjectWithAxialReferencePlacement(q) & exists k(axis1_placement(k) &
ReferencePointTemplate(k, px, py, pz) & ReferenceDirectionTemplate(k, dx, dy, dz) & exists p(MappingTriple(p, q, k) & axial_reference_placement(p))).
The template AxialReferencePlacementTemplate uses the ReferencePointTemplate (Table 7) and ReferenceDirectionTemplate (Table 8). These templates define the reference point and the direction respectively.
mantics of the templates presented at the alternative 1. The template ReferenceDirectionTemplate uses the template DirectionScaleTemplate (Table 9), that connect the three real values using the template ListOfReals3Template which has the same semantics presented at the alternative 1.
DirectionScaleTemplate(x, dx, dy, dz) <->
ObjectWithDirection(x) & exists k ( direction(k) & exists c(CoordinateSystem(k,c) & ListOfReals3Template(c,dx,dy,dz)) & exists p ( MappingTriple(p, x, k) & direction_scale(p)) ).
Bellow is presented a graphic example of templates instantiations (Fig. 5), that uses the same diagram language and values of the circle instantiation proposed at the alternative 1: a circle with a radius which the value is 3, with the position(1,2,3) and the direction expressed by the coordinate (1,0,0). Alternative 3: Trying a Balanced Approach. This approach presents two alternatives of intermediate granularity using a high level template. It aims to propose a model whose properties are explicit, to simplify the process of constructing queries in alternative 1 and simplifying the model construction in alternative 2, using all of its elements. In our first attempt, called CircleTemplateAlternative3 1, a higher level of abstraction is presented to construct instances of the model in the alternative 1. It uses all of its elements with a new template that constructs all the necessary instances, as a procedure that encapsulates all the process. This template signature is present in Table 10. The CircleTemplateAlternative3 2 presents a more compact process of individuals construction which does not affect query construction negatively. Its template signature is shown in Table 10. The signature is the same for both alternatives in this approach, differing in its axioms, as follows.
CircleTemplateAlternative3_1(q,rd,rl,ru,px,py,pz,dx,dy,dz)<-> circle(q) & RadiusTemplate(q, rd, rl, ru) & MetricSpacePointTemplate(q, px, py, pz) &
DirectionTemplate(q, dx, dy, dz).
CircleTemplateAlternative3_2(q,rd,rl,ru,px,py,pz,dx,dy,dz)<-> circle(q) & RadiusTemplate(q, rd, rl, ru) & AxialReferencePlacementTemplate(q,px,py,pz,dx,dy,dz).
The effort in the development and application of the ISO 15926 standard contributed with
a new paradigm of information management for the Oil e Gas industry, that will reduce
the costs in this area [
In future works, the main objective is to develop the standard researching subjects as the implementation of tools to help domain experts use the ISO 15926 standard, i.e. software to model and verify ISO 15926 templates, as well as an environment to create and to manage distributed data bases built upon the ISO 15926 proposed paradigm, building on the accumulated experience of the iRING User Group etc.; Implementation of the models using Web Ontology Language using the ISO 15926P- art8, envolving studies correlated with present day ontology challenges such as: how to store the ontology, how to manage the RDF triple store, how to make an efficient query across distributed RDF databases on the web; Design of an architecture to support format neutral exchange of 2D and 3D documents, based on SPARQL Endpoints providing federated management of process plant item symbology and Engineering document templates.
The authors thank TecGraf/PUCR-io Computer Graphics Techn ology Laboratory and CNPq, for supporting this work, the PCA Geometry Special Interest Group and most especially Mr. Onno Paap for his advice and encouragement.
ISO 103031-04 (2000). Integrated application resource: Fi nite element analysis.
ISO 159267- (2011). Implementation methods for the integra tion of distributed systems:
Template methodology.