Zone of Theoretical Visibility Assessments

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Zone of Theoretical Visibility Assessments

What are Zones of Theoretical Visibility Assessments?

Zones of Theoretical Visibility Assessments (ZTVs) are a process of collecting elevation data and mapping it onto digital software in order to determine the theoretical visibility of a planned development object. ZTVs, also referred to as Zones of Visual Influence (ZVI), are used to create 3D models of a landscape, which allows for the definitive analysis of visual impacts by development in all directions. 

Rbmp employs the most advanced ZTVs available in the form of integrated OS Terrain 5 DTM (Digital Terrain Model) and LiDAR (Light Detection and Ranging) scans to determine theoretical visibility of any location. To assess the value of landforms, surveyors utilise OS Terrain 5 DTM to construct a bare-earth model based on detailed elevation data in which specific blocks may represent houses, trees, and other landscape features. 

Augmented by LiDAR datasets, these surface models can develop into high-resolution 3D elevation maps where even minute geographical features as small as 25cm across can be visualised and assessed. With composite datasets of terrain mapping technology at their disposal, ZTV specialists can produce colour-coded areas of visibility and non-visibility to be reviewed in a thorough and accurate visibility impact assessment. 

Zone of Theoretical Visibility Assessments

Why Use ZTVs?

Zones of Theoretical Visibility Assessments play a major role in accurate Landscape and Visual Impact Assessments and create objective, quantifiable evidence of the visibility of an object based on scientific elevation analysis. Without ZTVs, it would be very difficult to have an understanding of how elevations play a role in views and to what extent development will affect surrounding visibility. With the geographic data provided by ZTVs, it’s possible to create a 3D map of the landscape and match specific vantage points with theoretical data that includes development objects. 

ZTVs are ideal in various terrains from open spaces where visual obstructions are limited and visibility elements are clearly defined to urban and rural settings where accurate composite data represents landscape obstructions such as vegetation and buildings. ZTVs are also useful in contributing to LVIAs for the purpose of devising conclusive testimonies based on a combination of geographic, man-made, and other visibility factors. 

Zone of Theoretical Visibility Assessments


Zones of Theoretical Visibility Assessments involve digital elevation mapping in-field, where comprehensive data on the terrain’s current status is collected and transferred to 3D mapping software. Within the software, design elements of future development are replicated and mapped against the geographically-accurate terrain, producing unique areas of visibility and non-visibility on which a map can be based. 

Using LiDAR composite data, this process can also account for buildings and man-made objects as well as vegetation and other obstructive factors not included in the development design. Visibility maps created with the help of ZVTs are instrumental to site surveys and LVIAs, as they highlight specific locations and vantages where visibility can occur and helps refer to those positions for further review in the assessment process.  

What are the Benefits of Using Zones of Theoretical Visibility Assessments?

Zones of Theoretical Visibility Assessments provide accurate geographical representation of the development site and surrounding areas where visibility may be affected. With the data collected by ZTVs, it is possible to present a clear line-of-sight between every coordinate contained within the visibility map. 

ZTVs are particularly useful in the case of wide areas where man-made obstructions (such as buildings) and natural vegetation are limited, and the biggest factors of visibility are geographical features and the curvature of the earth. However, through the use of integrated mapping technologies like OS Terrain 5 DTM and LiDAR, ZTVs can produce inclusive data of man-made and natural visibility obstructions as well as additional data collected by GIS and other methods which are entered into the terrain models. These comprehensive models are typically the basis of complete Landscape and Visual Impact Assessments, and allow developers to modify future designs and implement visual impact mitigation wherever necessary. 

Are there Any Limitations?

ZTVs are typically part of a comprehensive visual assessment project, and have certain limitations when conducted on their own. Because ZTVs measure geographic elevation, other objects which may affect visibility, such as buildings, trees, and various boundaries unique to the location will need to be studied with the help of other methodologies and accounted for within the 3D mapping parameters. Other factors such as scale, distance visibility, atmospheric conditions, and seasonal variations may also not be included in the assessment. 

Without conclusive data on actual visibility that accounts for obstructions, ZTVs are sometimes left to estimations of visual barriers, which detracts from the data’s objectivity and may not accurately represent the actual visibility of a location. For these reasons, ZTVs are a useful tool in achieving a comprehensive visual assessment and work best when augmented by various other technologies and research. 

Why Choose rbmp?

Rbmp utilises the latest and most advanced methodologies to deliver accurate Zone of Theoretical Visibility Assessments on behalf of clients across a wide-variety of industries with project goals in residential developments, commercial developments, renewable energy, oil and gas, transportation, and more. Whether you require a standalone ZTV assessment in areas of limited visual obstruction or a complete Landscape and Visual Impact Assessment in a rural or urban setting, rbmp offers competitive pricing while adhering to the highest standards of research and data collection in the industry. 

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