Specialist Survey Techniques
Specialist survey techniques, such as photogrammetry and laser scanning, are a fundamental component of any heritage project.
Often referred to as metric or measured survey, they provide visual and metrically accurate base data for a variety of heritage applications including conservation planning, condition surveys, decay monitoring, recording, architectural analysis, archaeological investigation and site presentation.
Direct survey techniques
These are used where there is a need for specific survey information that requires data selection at the point of capture. They rely on the surveyor understanding the selection requirements of the project as well as the technical constraints on the technique.
They include hand survey as well theodolite/total station equipment that uses active, non-contact distance measurement technologies. Guidance on such surveys can be found in Measured and Drawn.
Indirect survey techniques
These are used where there is a need for mass data capture or when the size or extent of the subject is too large for direct techniques to be suitably deployed.
They are typically based on image capture, be it photographic or laser-based (to derive a point-cloud) and often require some post-processing in order to derive the required survey outputs.
They include rectified photography, photogrammetry, orthophotography and laser scanning. Further guidance on the use of such techniques can be found in 3D laser Scanning for Heritage
Recent developments in multi-image photogrammetry and machine vision have led to increased use of Structure-from-Motion (SfM) across aerial, terrestrial and close-range applications. SfM allows three-dimensional structures to be derived from two-dimensional image sequences.
Reflectance Transformation Imaging (RTI) is an innovative multi-light imaging technique that utilises a pre-fabricated dome to produce an interactive output for revealing subtle surface relief. Further information about this technique can be found in
Multi-light Imaging for Heritage Applications
Survey standards and specifications
Use of a defined survey standard allows:
- An understanding of the project requirements by both client and end-user
- Data consistency
- Management of client expectation
- A focus on what an end-user needs from a survey technology.
Metric Survey Specifications for Cultural Heritage
To ensure metric survey data is both appropriate and 'fit for purpose', Historic England has developed a standard specification for metric survey.
Now in its third edition this document includes all metric survey techniques that are currently applied across a range of heritage applications. This includes laser scanning, multi-image photogrammetry/Structure-from-Motion (SfM), the capture of low level aerial imagery using Small Unmanned Aircraft (SUA) and Building Information Modelling (BIM), that are all being increasingly applied across cultural heritage professions.
The title ‘Metric Survey Specifications for Cultural Heritage’ reflects a more generic approach to specification as now used by the Royal Institution of Chartered Surveyors (RICS).
There are further client guides available from The Survey Association.
Building Information Modelling (BIM)
BIM is a process of illustrating, in digital terms, all the elements that compose a building. It allows a project team to collaborate and create a single source of data that assists construction, estate & facilities management processes throughout the life-cycle of a building.
Within Historic England an internal BIM Special Interest Group (BIMSIG) exists that through the Heritage Science strategy is considering the impact of BIM across heritage.
Historic Places Investigation
Also of interest...
Historic England experts use airborne remote sensing methods to identify, record and monitor the condition of heritage assets
Historic England experts investigate how geophysics and specialist survey methods can be used to learn about heritage assets