Abstract
Photogrammetry is currently facing some challenges and changes mainly related to automation, ubiquitous processing and variety of applications. Within an ISPRS Scientific Initiative a team of researchers from USAL, UCLM, FBK and UNIBO have developed an open photogrammetric tool, called GRAPHOS (inteGRAted PHOtogrammetric Suite). GRAPHOS allows to obtain dense and metric 3D point clouds from terrestrial and UAV images. It encloses robust photogrammetric and computer vision algorithms with the following aims: (i) increase automation, allowing to get dense 3D point clouds through a friendly and easy-to-use interface; (ii) increase flexibility, working with any type of images, scenarios and cameras; (iii) improve quality, guaranteeing high accuracy and resolution; (iv) preserve photogrammetric reliability and repeatability. Last but not least, GRAPHOS has also an educational component reinforced with some didactical explanations about algorithms and their performance. The developments were carried out at different levels: GUI realization, image pre-processing, photogrammetric processing with weight parameters, dataset creation and system evaluation. <br><br> The paper will present in detail the developments of GRAPHOS with all its photogrammetric components and the evaluation analyses based on various image datasets. GRAPHOS is distributed for free for research and educational needs.
Highlights
Photogrammetry is nowadays facing new challenges and changes related to automation, ubiquitous processing, variety of datasets and applications
4.1 Image pre-processing influence in feature extraction and matching process The use of the correct image pre-processing algorithm is the basis for a successful processing of an image dataset
This article has reported the developed educational tool named GRAPHOS. It was a joint project among USAL, UCLM, FBK and UNIBO supported by an ISPRS Scientific Initiative
Summary
Photogrammetry is nowadays facing new challenges and changes related to automation, ubiquitous processing, variety of datasets and applications. Performances, reliability, transparency, repeatability, accuracy potential and usability vary a lot according to packages, applications and users (see https://en.wikipedia.org/wiki/Comparison_of_photogrammetry_ software for a quite complete list of tools). With the aim to deliver a free image processing package able to fulfil all photogrammetric requirements, a team of researchers developed the GRAPHOS tool. GRAPHOS aims to bring photogrammetry and computer vision even more closer realizing a tool which integrates different algorithms and methodologies for automated image orientation and dense 3D reconstruction from set of unordered images. Automation was not the only keydriver of the tool but precise processing, reliability, repeatability and guidelines for non-experts were considered. Since the photogrammetric process involves basically three different steps (e.g. extraction and matching of image correspondences, camera calibration and image orientation, dense point cloud generation), the specifics goals of GRAPHOS are: 1. An automatic estimation of sensor size parameters was included for non-expert users and unknown cameras
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