Building information models are actually representations of de- signed reality, aimed at improving the perception of ideas and ex- change information [41]. By advanced rendering of the models and surroundings, the user is offered a greater amount of information. This can reduce the possibility of misinterpretation of the designs [3]. With technological progress greater degree of realism can be achieved but according to this theory the perfect model cannot be established since reality presents a limit that can be approached but never reached [36]. Augmented reality on the other hand offers a dif- ferent approach. It takes the live picture of real surroundings as a base to which virtual elements are added. With that in a given point in time and space the user’s interpretation of proposed digital solutions can be easier [14].

There are many terms used to define the segment of continuum between the extremes of the real and the virtual: mixed reality, am- plified reality, augmented reality, mediated reality, diminished real- ity, augmented virtuality, virtualised reality [22]. In this paper the term, augmented reality (AR) is used since our application augments the insight to the real situation for the user.

2.2. Building  information modelling/model

By definition the building information modelling is a process of digital designing, which results in some form of a building informa- tion model (BIM). Ideally it should include all the data needed for the construction instead of the data being scattered throughout numer- ous drawings, folders, tables, reports, documents, etc. [9].The basic premise of building information modelling is to enable frictionless collaboration of different actors (professions) at various stages of a building life cycle, integrated around a shared model. The actors may enter, retrieve, update or adopt the information in BIM and with that justify their roles as the participants in the construc- tion process [6,24]. The 4D BIM is a model that includes the tempo- ral properties. The 5th and 6th dimensions of BIM sometimes denote cost and facility management [32].

2.3. Project documentation

Formally speaking, the project documentation that is required by Slovenian legislation is defined by the Construction Act [40]. It should consist of the conceptual design, preliminary design, basic design, de- tailed design, and as-built design.

In this paper the term “project documentation” is used broader than formally defined by Slovenia legislation. The term project doc- umentation is used to denote a set of all documents needed for the construction. It includes all information contained in building infor- mation models.

2.4. Intersection between conscious real and virtual

The role of augmented reality can theoretically be explained in the context of the meaning triangle in Fig. 1 [31]. The concept is an idea in the mind that refers to that specific referent (real world object). The symbol is a visual or audible signal symbolising the idea about that referent.

摘  要  近年来，信息模型的建立大大提高了设计信息所想表达的内容。信息模型用于集成项目开发的初始阶段。然而，在建筑工地上，这些设计仍然主要表现为基于线条的图纸或便携显示器上的投影。一种通用技术，可以将信息和将其置于时间、地点和上下文中是增强现实。所讨论的具体研究问题是：(1)增强现实技术在土木工程中是否有潜在的应用；(2)与之相比对于其他技术来说，这是潜在的；(3)采用它的主要障碍是什么。一般的研究问题的方法是开发一种评估技术潜力。建造了一个原型，它被测试在一个实际的建筑工地，以评估它的使用潜力和使用研究方法。然后对潜在用户进行了一组结构化的访谈。将原型与传统的表示方法进行比较。使用这种方法，我们发现增强现实技术将与从二维线图到真实感三维投影的转变一样重要。采用的主要障碍是不成熟的核心虚拟现实技术、建筑企业的保守性和建筑信息模型的规模。