Using recently aquired photogrammetry software, GBG is able to generate perspective corrected orthophotos from standard digital camera images - and by clever use of the software, thermal images too.
Using pattern matching techniques, carefully taken overlapping images can be anaylsed to determine the 3D structure. This is then used to generate a textured surface model, which can be aligned to generate a true orthoimage.
The image below shows an example generated at our Cambridge Office (Click for larger version - 800KB)
The technique requires that sufficiently similar and overlapping images are taken from a number of different viewpoints. They must also contain an element of random and heterogenous detail, allowing features to be matched reliably between photos. It also requires that reflections from the object surface are diffuse rather than specular. Brick and stone buildings are ideal, whereas reflective or uniform/homogenous surfaces would not be suitable.
In cases where photogrammetry techniques could not be applied, laser scanning can be employed to generate the surface model, and both optical and thermal images can be applied to that surface so long as there are a handful of features that can be matched between each image and the modelled surface.
Full 3D versions of the example above can be viewed by downloading the PDFs below - requires Acrobat Reader 9 or later
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