Cihan Altuntas

The registration of point cloud data from range imaging camera

AbstractThe measurement and 3D modelling techniques have been evolved as parallel technological improvements. Every new technique provides an opportunity for low-cost and fast measurements. The latest method for 3D measurement is the range imaging (RIM) camera. The new period in photogrammetry and 3D modelling applications has begun with the RIM cameras, and it has brought new research areas for scientists. The measurement capabilities, accuracies and application areas of RIM cameras have been increased by the time. In this study, the registration of point cloud data of RIM camera was investigated to perform 3D modelling task.

Laser Scanning and Data Integration for Three-Dimensional Digital Recording of Complex Historical Structures: The Case of Mevlana Museum

Terrestrial laser scanning method is widely used in three-dimensional (3-D) modeling projects. Nevertheless it usually requires measurement data from other sources for full measurement of the shapes. In this study a 3-D model of the historical Mevlana Museum (Mevlana Mausoleum) in Konya, Turkey was created using state-of-the art measurement techniques. The building was measured by terrestrial laser scanner (TLS). In addition, some shapes of the indoor area were measured by a time-of-flight camera. Thus, a 3-D model of the building was created by combining datasets of all measurements. The point cloud model was created with 2.3 cm and 2.4 cm accuracy for outdoor and indoor measurements, and then it was registered to a georeferenced system. In addition a 3-D virtual model was created by mapping the texture on a mesh derived from the point cloud.

Pair-wise automatic registration of three-dimensional laser scanning data from historical building by created two-dimensional images

Abstract. Registration of a point cloud is a great challenge in the process of laser scanning data. So far, many registration methods have been introduced by range data, integrated camera image, and a combination of them. Moreover, the automatic registration of three-dimensional point clouds is an important research topic in both geomatics and computer sciences. In this study, keypoint-based registration of point clouds was introduced. Intensity images were created from the laser scanning data, and then a pair-wise automatic registration was performed with the keypoints extracted from the intensity images by a scale invariant feature transform (SIFT) and affine SIFT (ASIFT). The results were compared with the iterative closest point, which has high accuracy and is the extensively adopted method for the pair-wise registration. Consequently, SIFT and ASIFT keypoints which were extracted from intensity images can be exploited to pair-wise automatic registration of the point clouds.

Keypoint based automatic image orientation and skew investigation on tie points

Purpose – The relative orientation (RO) is an important step on photogrammetric processes of stereoscopic images. The relationship between the stereoscopic images is constructed by tie (conjugate) points. Many automatic tie point selection methods have been introduced by photogrammetry community so far. The scale invariant feature transform (SIFT) and speeded‐up robust features (SURF) are frequently used for automatic tie point selection from stereoscopic images. However, any research has been performed related to RO errors (y‐parallaxes) on SIFT and SURF extracted tie points. The purpose of this paper is to compute errors on tie points and investigate their distributions on the model area in terms of size.Design/methodology/approach – The experimental studies were performed on an historical building as it enables more tie points for investigation. While a couple of the stereoscopic images include rich details, the other has poor details. The image orientation and tie point selection accuracy were evaluat...

Georeferencing of ground-based LIDAR data using continuously operating reference stations

Abstract. Terrestrial laser scanning has been used for various outdoor visualizations such as urban, construction, excavations, and land topography. Since laser scanning data have their own local coordinates in each station, a three-dimensional point cloud model of the object of interest is created in the local coordinate system by the combination of these measurements. For spatial queries and computations, the point cloud and other spatial data should be combined in a common coordinate system. In this study, a terrestrial laser scanner (TLS) and global navigation satellite system (GNSS) receiver were integrated for the registration of the laser scanner measurements into the geodetic coordinate system. Two georeferencing methods based on the continuously operating reference stations in the network Turkey (CORS-TR) were introduced. After the building was modelled by integrating the TLS and the GNSS receiver, the point cloud model that was created was registered to the international terrestrial reference frame. The registration was performed with 0.05 m root mean square error for the two georeferencing methods.

Range and image sensor combination for three‐dimensional reconstruction of objects or scenes

Purpose – Laser scanning is increasingly used in many three‐dimensional (3‐D) measurement and modeling applications. It is the latest technique used in 3‐D measurement, and is becoming increasingly important within a number of applications. However, many applications require photogrammetric data in addition to laser scanning data. The purpose of this paper is to present a range and image sensor combination for three‐dimensional reconstruction of objects or scenes.Design/methodology/approach – In this study, a Nikon D80 camera was mounted on an Ilris 3D laser scanner and CPP was estimated according to the laser scanner coordinate system. The estimated CPP was controlled using three different methods which were developed in this study and a sample application as coloring of point cloud using image taken by the camera mounted on the laser scanner was performed.Findings – It was found that when a high‐resolution camera is mounted on laser scanners, camera position parameters (CPP) should be estimated very acc...