3D real estate visualisation and virtual property walkthroughs

1 Introduction
2 Related articles on Designing Buildings

[edit] Introduction

3D real estate visualisation refers to the use of computer-generated imagery (CGI), rendering software and digital environments to represent existing or proposed properties in three dimensions. Virtual property walkthroughs extend this capability by allowing users to navigate through a digital representation of a property interactively, using a web browser, computer, mobile device or virtual reality (VR) headset.

These technologies are used across residential, commercial and mixed-use development to communicate design proposals, support stakeholder engagement, assist with the presentation of planning proposals, market properties and help prospective purchasers or tenants understand spaces before construction is complete or before visiting a property.

[edit] Types of 3D visualisation

Several formats are used for property visualisation and virtual walkthroughs.

Still 3D renders are high-resolution static images generated from three-dimensional models. They can depict interiors, exteriors, streetscapes, aerial views and proposed developments, and can represent materials, furniture, landscaping, lighting and surrounding context.

3D animated walkthroughs are pre-rendered sequences that move through a digital representation along a predetermined route. They can be used to demonstrate spatial relationships, circulation, materials, lighting and proposed finishes, but unlike an interactive walkthrough they do not normally allow the viewer to control their route.

Interactive virtual tours provide real-time navigation through a digital environment. The user can normally change their position and viewing direction and, depending on the system, interact with objects, materials, lighting or other information. Such environments can be developed using real-time rendering or game-engine technology and delivered through computers, mobile devices or headsets.

360-degree photography and virtual tours use panoramic photographs captured from physical locations. Individual panoramas can be linked to create a navigable tour. This is different from a fully modelled three-dimensional environment because the user is viewing photographic imagery rather than freely navigating a computer-generated model.

Virtual reality walkthroughs use a VR headset or other immersive display to provide an interactive computer-generated representation. They can provide a strong sense of scale and spatial relationships, although the quality and accuracy of the experience depend on the underlying model and the hardware and software used.

Augmented reality (AR) combines digital content with a view of the physical environment. For property and construction applications, this can allow a proposed building, component or interior arrangement to be viewed in relation to an existing physical location.

[edit] Applications in the construction and property sector

3D visualisation is widely used for the presentation and communication of proposed developments. Photorealistic renders and interactive environments can help prospective purchasers and tenants understand layouts, finishes, furniture and external spaces, particularly for properties that have not yet been constructed.

Architects, designers and other project participants can use three-dimensional models and walkthroughs to communicate proposals to clients and other stakeholders who may find conventional technical drawings difficult to interpret. Interactive models can also help identify design issues and facilitate discussion of alternative layouts, materials and finishes during design development.

Visualisation can form part of planning application material where appropriate. Three-dimensional representations can help communicate the massing, appearance and relationship of a proposed development to its surroundings. Whether particular visualisations are required or useful depends on the nature of the proposal and the requirements of the relevant planning authority.

In interior design and space planning, three-dimensional environments can be used to assess furniture layouts, finishes, colour schemes, lighting arrangements and circulation before physical work is undertaken. Changes can be made to the digital model and alternative options presented without modifying the physical space.

During construction, visualisation can be combined with Building Information Modelling (BIM) to communicate design information, coordinate building elements and support construction planning. Three-dimensional models can also be used as the basis for clash detection and, where appropriate, linked to programme information to create four-dimensional representations of construction sequencing.

[edit] Technology and software

The production of a 3D visualisation generally involves several stages. A three-dimensional model is first created or obtained from CAD, BIM, surveying, scanning or other digital information. Geometry is then prepared for the intended application, with materials, textures, lighting and environmental information added as required. The resulting model can be rendered as a still image or animation, or prepared for real-time interaction.

Rendering systems range from offline rendering engines, which can produce highly detailed images but may require significant processing time, to real-time rendering systems that generate images interactively. Game-engine technology can be used to create interactive walkthroughs and VR environments.

For existing properties, three-dimensional environments can also be generated from photographs, laser scanning, photogrammetry or other reality-capture techniques. The resulting digital representation may contain different levels of geometric and photographic information depending on the capture method and intended use.

The choice of software and hardware depends on the required visual quality, degree of interactivity, model complexity, delivery method and available computing resources. A model created for technical BIM purposes may require additional preparation before it is suitable for high-quality visualisation or real-time navigation.

[edit] Integration with BIM

3D visualisation is closely related to, but distinct from, Building Information Modelling. BIM is a process for creating, managing and exchanging information about built assets, whereas visualisation primarily concerns the graphical representation and communication of that information.

A BIM model can provide geometry and associated information for visualisation, while a visualisation can be derived from a BIM model without necessarily retaining all of the information contained within the original model. Consequently, exporting geometry to a visualisation system can result in information being simplified, converted or omitted.

The level of detail and accuracy required should therefore be determined by the intended purpose. A visually realistic marketing image may require detailed materials, lighting and landscaping but little non-graphical information, whereas a BIM model intended for construction or asset management may require substantially more structured information.

Maintaining appropriate links between visualisation outputs and source models can also be important where design changes occur. Without suitable model and information management procedures, visualisations can become inconsistent with the current design.

[edit] Accessibility and remote property viewing

Virtual walkthroughs can allow prospective purchasers, tenants, investors and other stakeholders to examine properties without being physically present. This can be particularly useful for properties that are geographically remote, under construction or not yet available for conventional viewing.

Web-based walkthroughs and 360-degree tours can generally be accessed using standard computers and mobile devices, while VR walkthroughs require compatible hardware. The accessibility of an experience therefore depends on its delivery method, device requirements, internet connection, file size and software compatibility.

Virtual viewing can complement rather than replace physical inspection. Digital representations may not communicate all aspects of a property, including acoustic conditions, tactile qualities, odours, actual daylight conditions, defects or variations in workmanship and materials.

[edit] Limitations and considerations

3D visualisation can provide a convincing representation of a proposed property, but it remains a representation rather than the physical building. The apparent accuracy of a visualisation depends on the accuracy of the underlying model, assumptions about materials and finishes, lighting conditions, surrounding context and the techniques used to produce the image.

Photorealistic imagery can also create an impression of certainty that may not be justified where aspects of the design remain subject to change. This is particularly relevant to marketing material for properties sold before construction. Visual representations should therefore accurately communicate material aspects of the property and should not create a misleading impression.

Interactive walkthroughs can require substantial computing resources, particularly where they contain detailed geometry, high-resolution textures, complex lighting and large environments. Web-based applications must also take account of bandwidth, loading times and compatibility with different devices.

The cost and time required to produce visualisations vary considerably. Simple models or images can be produced relatively quickly, whereas detailed interactive environments may require extensive modelling, texturing, lighting, programming and testing. Costs are affected by the complexity of the property, required level of detail, number of views, degree of interactivity and whether an existing model is available.

Privacy and data protection can also be relevant where digital models are created from existing properties. Detailed scans, photographs and digital twins may contain information about private spaces, occupants, security arrangements or personal possessions. Appropriate permissions, access controls and data management procedures may therefore be required.

[edit] Regulatory and ethical considerations

Visualisations used in property marketing should accurately represent the property being offered. Where a development is proposed, it should be clear which elements are illustrative or indicative and which have been confirmed. Changes to the design, specification, landscaping, surrounding development or site conditions can affect the relationship between a visualisation and the completed property.

Consumer protection legislation can apply where visual representations are used in property marketing. In the UK, businesses must take care not to provide misleading information or create misleading overall impressions about material characteristics of a property.

Visualisations prepared for planning purposes have a different function from marketing images. Planning visualisations should provide an appropriate representation of the proposal and its context so that the likely visual effects can be assessed. The required type and level of visual information will depend on the proposal and the relevant planning process.

Used appropriately, 3D visualisation and virtual walkthroughs can improve communication between project participants and provide a useful means of presenting spatial information. Their value depends on the accuracy and currency of the underlying information, the suitability of the chosen technology and the purpose for which the visualisation is being used.