Building Surveying and Photogrammetry
These services are totally non intrusive surveying techniques allowing for highly accurate measurement and recording as well as the development of precise elevations. The different surveying solutions below have an accuracy in line with laser scanning and can be completed in a fraction of the time and at a lower cost.
Photogrammetry and CAD Services
This takes the recording of a building beyond record images to create accurate elevations and CAD-compatible rendered 3D models. A full photographic survey allows for post-capture analysis using dedicated photogrammetric software to extract highly accurate measurements, scale models and elevations from the surveyed building. This provides a quick and non-intrusive survey method, with site time much less than laser scanning but with comparable results. These surveys are fully compatible with CAD, (as DXF files, and other formats where necessary) allowing 3D models and elevations to be exported directly to your system. As well as providing highly accurate measured surveys, photo-rendered 3D visualisations are ideal to use in presentations to planners and other groups. Photo-rendering helps convey texture and detail in a way that a line drawing cannot.
This service provides a fully accurate survey in a fast and efficient manner, usually involving only a single day on site, and so is a cost effective alternative to laser scanning. The service can also be used retrospectively with historic images to create rendered models and elevations of buildings shown in archival photographs. Files can also be exported to Google Earth to allow buildings to be placed on top of orthographs to obtain a true location.
These services can be broken down into certain specific applications.
Photographic Surveys
A scaled image survey of all building facades is available at various resolutions depending on what level of detail is required. Visible control scales allow for highly accurate rectification of the images. High resolution surveys involve the stitching of 3mx3m panels which cover the whole facde into a single scaled image. Lower resolution surveys involve single images covering larger areas of the building. The output from this image is as a scaled TIFF file.
Digitally Rectified Surveys
As well as being a service in itself this also forms the backbone of the additional services that are available. This survey involves the creation of a highly accurate control net over the surface of the whole building. A photogrammetric survey is then carried out with a control frame in each image to maximise the accuracy of the final survey. Each individual pixel in the image is remapped to correct for distortion both in and outside the camera. A fully measured perimiter survey is also included as part of this survey. A variety of output options are available for this survey including rectified images and drawn elevations. This survey allows for the extraction of highly accurate measurements from the output material which have an accuracy in line with laser scanning, available at a fraction of the cost.
Stone by Stone Surveying and Elevations
The data that is collected during a rectified image survey facilitates the creation of stone by stone surveys or elevation projections. Stone by stone surveys can be completed over the whole facade or over areas of particular importance. Elevations can cover every aspect of a whole building or only the most important features. All elevations are to a perfect scale and suitable for precise measurement. Both types of survey can be colour coded for advanced analysis to highlight certain elements or stone types. For instance, stones in bad condition or those that are going to be removed can be highlighted in the elevations. The examples below illustrate the output possible from this type of survey. The tracing of each feature is completed at a single pixel tolerance giving a very high level of accuracy to the final survey. A variety of surveys are available combining elements of both stone-by-stone and facade surveys at a range of resolutions. Each survey is provided as a raster image or a vector file for use in CAD.
The methodology behind this survey is similar to the 'point cloud' approach of a laser scanner, with individual co-ordinates lifted of a corrected image (that is a perfectly accurate representation of the 2D plane under analysis) and then plotted digitally in just the same way that a laser scanning operator would join the co-ordinates of the 'point cloud'. This method allows us to provide a highly accurate and customisable survey tailored precisely to your needs.
Original rectified image
Accurate stone by stone elevation
Elevations with colour coded features to allow sophisticated analysis
(In this case stones in bad condition to be removed)
Click here to download a .dxf vector file for CAD
Advanced Colour Recording
During the Photogrammetric survey high precision colour data is recorded at resolutions up to individual stones. This can then be analysed during rectification, recording an extra level of historical detail. This is a particularly valuable application for mosaics, wall-paintings and stained glass. It is also an excellent method to allow for the analysis of plaster and render colours.
Orthographic Surveying
This is a step up from rectified imaging and invloves the creation of a 3D photo realistic model of the building. This technique produces very appealing fly-around views. As an additional benefit the images that are required for this would facilitate a high resolution roof survey. This survey can also provide the backbone of photographic virtualisations of proposed alterations for complex planning applications.
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