Visual Impact Assessment
Before the visual effect of a proposed development can be understood, there needs to be a clear picture of what exists now. Within a Visual Impact Assessment, the existing visual environment provides the baseline against which proposed visual change can be considered.
In Brief
The existing visual environment is the visual condition against which a proposed development is assessed. It may include the existing landscape and built form, vegetation, landform, development patterns and other elements that shape relevant views. Establishing this baseline helps the assessment distinguish what already forms part of the visual environment from the change introduced by the proposal.
The existing visual environment describes the visual conditions present before the proposed development is introduced into the assessment.
Depending on the project and assessment methodology, this may include natural and built elements such as landform, vegetation, buildings, infrastructure, open space, water, development patterns and other features that contribute to the appearance and experience of relevant views.
These elements do not need to be visually attractive or unchanged landscapes. Existing urban development, roads, utilities, industrial structures and other modifications may already form part of the visual baseline.
The purpose is to establish what is already there so that the visual change associated with the proposal can be understood in context.
A Visual Impact Assessment is concerned with change. Without understanding the existing condition, it is difficult to distinguish the effect created by a proposal from the visual characteristics that are already present.
The baseline provides a reference point for considering questions such as how much of the view may change, whether a new element introduces contrast, whether existing features provide screening and how the proposal relates visually to its surroundings.
It also helps prevent existing development from being incorrectly attributed to the proposed project. The assessment can separate the visual condition that already exists from the additional change being introduced.
For this reason, establishing the existing visual environment usually occurs before the visual effects of the proposal are evaluated.
Visual impact is an assessment of change. The existing visual environment establishes what is already present so the change introduced by a proposal can be understood.
The visual environment is usually made up of several interacting elements rather than a single feature.
Landform can influence the shape and enclosure of a view. Vegetation may frame, filter or screen what can be seen. Buildings and infrastructure can establish patterns of scale, form and development. Roads, open spaces and waterways can influence where and how people experience the surrounding environment.
The relative importance of these elements depends on the project and the particular view being assessed. A dense urban street, coastal outlook, rural landscape and industrial precinct will each have a different visual baseline.
The assessment therefore needs to describe the characteristics that are relevant to understanding the proposed visual change rather than attempting to catalogue every feature in the surrounding area.
Yes. The existing visual environment is not limited to natural landscape features.
Existing houses, commercial buildings, infrastructure, roads, utilities and other established development may all contribute to the current visual condition. In some locations, built form may be one of the defining characteristics of the view.
This can be important when considering how a new proposal relates to what is already present. A development may introduce a new visual element, reinforce an existing pattern or create a contrast with the surrounding condition.
The assessment considers that relationship without assuming that an already developed visual environment is necessarily insensitive to further change.
Not necessarily. The concepts can overlap, but they are not interchangeable.
The existing visual environment provides the baseline visual condition relevant to the assessment. Landscape character is concerned more specifically with the characteristics and patterns that contribute to the identity or character of a landscape or place.
Depending on the methodology, understanding landscape character may form part of establishing the wider visual context. A VIA may also focus more closely on the views experienced by particular visual receptors.
The terminology and level of landscape analysis required should therefore follow the scope and methodology of the particular assessment.
No. They may use some of the same project information, but they answer different questions.
A Site & Contextual Analysis examines the broader conditions that shape a site and its development context. This can include surrounding built form, land use, access, physical constraints and other contextual information relevant to planning and design.
Within a VIA, the visual baseline has a narrower purpose. It establishes the existing visual condition needed to understand the visual change created by the proposal.
Where broader site and contextual analysis is required, that work can inform the VIA without the VIA needing to reproduce the full site analysis.
The way the visual baseline is documented depends on the project and assessment methodology.
Site observations and photography can provide a record of existing views and visual conditions. Plans, mapping and available project information can help establish the location and relationship of relevant features. For some projects, additional landscape or visual information may also be required.
The objective is not simply to create a photographic archive. The information needs to establish the aspects of the existing environment that are relevant to understanding the visual effects of the proposed development.
The documentation should also make it possible to distinguish clearly between the existing condition and any visualisation of the proposed condition.
A viewpoint provides a location from which part of the existing visual environment can be documented and assessed.
From that location, the assessment can describe the existing composition of the view before considering how the proposed development may alter it.
Different viewpoints can have very different baseline conditions. A proposal may appear against vegetation from one location, existing development from another and open sky from a third. These differences can influence how the same proposal is experienced.
For more on how representative assessment locations are identified, see How Are Viewpoints Selected for a Visual Impact Assessment?
Magnitude of visual change cannot be understood entirely from the dimensions of a proposed development.
The same development can create different degrees or types of visual change depending on the existing view into which it is introduced. Its apparent scale, visible extent, contrast and relationship with surrounding elements can vary between viewpoints.
Understanding the baseline therefore helps explain what is actually changing rather than assessing the proposal as an object in isolation.
The concept is explored further in What Is Magnitude of Visual Change in a Visual Impact Assessment?
Yes. Visual environments are not necessarily static.
Vegetation can grow or change seasonally. Buildings may be constructed or removed. Infrastructure can change, and other approved or proposed developments may alter the wider visual environment.
The appropriate baseline and any future development scenarios therefore depend on the assessment scope and applicable planning requirements. Existing conditions should not automatically be combined with every possible future change.
Where other relevant developments need to be considered together with the proposal, this may form part of a cumulative visual impact assessment.
No. An existing developed context does not automatically mean that further development will have limited visual effect.
A proposal may be consistent with some existing visual characteristics while still creating a noticeable change in scale, form, prominence or composition from particular viewpoints.
Conversely, a proposal introduced into a relatively open or undeveloped view does not automatically result in a particular impact rating. The effect needs to be considered through the applicable assessment methodology.
The baseline provides context for the assessment; it does not predetermine the outcome.
Establishing the existing visual environment is one part of a wider assessment process.
The baseline helps describe what exists before the proposal is introduced. Relevant visual receptors identify who may experience change, while representative viewpoints help show where that experience can be assessed. The proposal can then be considered in relation to the existing condition to understand the nature and extent of visual change.
Depending on the methodology, factors such as visual sensitivity and magnitude of change can then contribute to the assessment of visual effects or impacts.
Together, these steps allow a Visual Impact Assessment to evaluate a proposed development as a change to an existing visual environment rather than as an isolated object.
Continue Reading
Once the existing visual condition is understood, the next question is how substantially the proposed development changes what is experienced from a relevant viewpoint.
Understand magnitude of visual change →Visual Impact Assessment
The appropriate visual assessment scope depends on the proposal, site, surrounding visual environment and planning requirements.
Send us your plans and available project information. We can review the project and help identify the appropriate assessment pathway.
Start Your Project