Image-based 3D acquisition tool for architectural conservation

In this paper an image-based 3D acquisition tool is presented. The tool has been developed with architectural conservation in mind. The proposed tool is developed as part of a project that aims at developing a technology that enables the operator to build up an accurate three dimensional model without too much repetitive work starting from photos of the objects and measured reference coordinates. This model can in a later phase be used as a core for a multimedia database, to represent designs for interventions, or for distribution to the wider public. The presented 3D acquisition tool is largely automated. A limited amount of interaction is used to indicate the reference points in the images to allow global localization in world coordinates. These points are also used to simplify the matching process so that wide baselines can be coped with. Depending on the number of reference points the camera needs to be pre-calibrated or not. From this point on the approach automatically finds additional matches and refines the calibration. A globally consistent estimate can be obtained through bundle adjustment. The next step consists of dense depth estimation based on stereo matching. From the computed information a dense textured 3D surface reconstruction of the recorded structure is computed. The tool also allows extracting 2D slices or pointing measurements. The results can be used both for measurements and for visualization purposes.