Façade Surveying using Photogrammetry

London property developer – prime sector

A major central London property developer approached H+R about the possibility of surveying areas of internal brickwork that were due to be left exposed following refurbishment works. Not only did the client require a bill of quantities to form a schedule of repair works, but they also required conditions be marked up onto rectified photographs produced by H+R.

Having agreed a scope and specifications for the type of brick repair required by the architect, H+R faced several challenges in regard to image capture in such narrow and confined hallways.


H+R tackled the issues posed by using photogrammetry techniques employed during similar projects to capture entire elevations as single images to then mark-up during a second site visit. This involved the use of a high-resolution camera mounted on an extendable telescopic pole, allowing the H+R operative to capture images at a consistent and changeable height. A series of photographs were captured at the 1m, 1.3m, 1.7m and 2m mark (example seen below), allowing for overlap between images to aid in the photo-merge process. Photographs were then stitched together back at the office using several Autodesk programs by our qualified technicians to produce the final images for mark-up back on site.

Photogrammetry Case Study - Technology - (Image 3)

Using the rectified and/or stitched images of the requested areas (such as the one seen below), H+R returned to site to complete the survey work and designate cost-effective remedial repairs.

Each marked-up image was delivered to the client with an accompanying bill of quantities to allow the client to price the designated repair works accordingly before passing on the marked-up images to brick-masons to ultimately carry out the repairs.

H+R have found that marking up rectified photographs rather than drawn elevations for survey work can reduce the risk of any potential confusion between the repairs specified and those ultimately carried out. Marked-up photographs at high-resolution can often transparently represent defects to all stakeholders in a way that vector-based line drawings cannot.

Photogrammetry Case Study - Technology - (Image 2)