Orthophotography – and photo-textured 3D surface models, in general – are most important photogrammetric products in heritage
conservation. However, it is now common knowledge that conventional orthorectification software accepts only surface descriptions
obtained via 2D triangulation and cannot handle the question of image visibility. Ignoring multiple surface elevations and image occlusions
of the complex surface shapes, typically met in conservation tasks, results in products visually and geometrically distorted.
Tiresome human intervention in the surface modeling and image orthorectification stages might partly remedy this shortcoming. For
surface modeling, however, laser scanners allow now collection of numerous accurate surface points and creation of 3D meshes. The
authors present their approach for an automated production of correct orthoimages (and perspective views), given a multiple image
coverage with known calibration/orientation data and fully 3D surface representations derived through laser scanning. The developed
algorithm initially detects surface occlusions in the direction of projection. Next, all available imagery is utilised to establish a colour
value for each pixel of the new image. After back-projecting (using the bundle adjustment data) all surface triangles onto all initial
images to establish visibilities, texture ‘blending’ is performed. Suitable weighting controls the local radiometric contribution of each
participating source image, while outlying colour values (due mainly to registration and modeling errors) are automatically filtered
with a simple statistical test. The generation of a depth map for each original image provides a means to further restrict the effects of
orientation and modeling errors on texturing, mainly by checking closeness to occlusion borders. This ‘topological’ information may
also allow establishing suitable image windows for colour interpolation. Practical tests of the implemented algorithm, using images
with multiple overlap and two 3D models, indicate that this fusion of laser scanner and photogrammetry is indeed capable to automatically
synthesize novel views from multiple images. The developed approach, combining an outcome of geometric accuracy and
visual quality with speed, appears as a realistic approach in heritage conservation. Further necessary elaborations are also outlined.