Sunday, 17 June 2012

Methods of survey

It is common practise to select the method of documentation of historic buildings, tools and other resources necessary for the project based on

  •            Purpose of the Survey
  •          Contextual factors and complexity of the historic building
  •          Time and Cost factors
  •          Technical know-how of the working team

In this project, however, the deliverables are fixed i.e. Hand survey documents for four monuments within a fixed time and cost. The clients are still unsure about the purpose of the survey and have left it on the consultants to arrive at a suitable method and output.
As mentioned in a previous section, documentation of historic buildings was only carried out prior to civil works to aid in forming estimates of work. Although in the last few decades, more and more documentation works have been carried out to aid conservation works; rarely has it been used for the same and more and more documents have ended up in the archives.
It remains a huge challenge for the consultants to choose the right method and deliver a product that meets the Purpose of the survey; also overcoming the various constraints on site.
This section is an attempt to discuss the methods of documentation that are being conducted.

Hand Survey methods

The consultants are documenting the plan of the historic building using

  •           Triangulation; to arrive at an overall profile
  •            Chain and offset method for the details


The clients, lacking the technical knowledge of documentation over looked the provision of scaffolding and other such necessary supports and since height of the structure remains a constraint (6ft to 11ft), the consultants had to resort to photo rectification in order to document the exterior and interior elevations. Adding to this is the fact that the site is struck by monsoons for most of the project period due to which outdoor works becomes close to impossible. The number of working hands being limited, photo rectification seemed to be the most suitable option in this case. The facades are more or less flat and are less complex which would help reduce errors in the rectified photograph.  In cases where the room width is too narrow for photography, the consultants prepare a photo mosaic which is tested for accuracy by actual measurements.
The photographs taken are being rectified using Adobe Photoshop CS4 by correcting the lens distortion.

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