@CONFERENCE{MTMT:2688560, title = {Sphere Fitting On MS Kinect Point Cloud}, url = {https://m2.mtmt.hu/api/publication/2688560}, author = {Molnár, Bence and Charles, K Toth and Dorota, A Grejner-Brzezinska}, booktitle = {MAPPS/ASPRS 2012 Specialty Conference}, unique-id = {2688560}, abstract = {The Microsoft Kinect sensor is getting prominent in several applications beyond the original field of videogames. The main advantage of this 3D measurement device is the low price and easy software development. Kinect has a Flash LiDAR type sensor and RGB camera to provide colored 3D point cloud acquisition. Based on previous accuracy investigations, the range calibration results were found rather good for a low-end device. The accuracy, however, can be further increased with more sophisticated sensor calibration, especially by using the IR intensity values for co-registration, as the number of matching points between the depth and RGB images can be further increased, which may yield to better calibration performance. Previous experiences indicated some object distance dependent scaling issues for depth calculation; objects farther than 2 meters are scaled down, caused by the measurement quantization required for data transmission. In addition, the spacing of the points is growing with the object distance. This means that the common sphere fitting methods fail with Kinect on farther objects. Therefore, a new fitting method was developed for sphere fitting on Kinect acquired point cloud, which yields better results, even over 2 meters. This way, the raw measurement values can have high accuracy and, in particular, if some preliminary information about the object morphology exists.}, year = {2012}, orcid-numbers = {Molnár, Bence/0000-0002-2602-2684} } @inproceedings{MTMT:2684494, title = {Calibrating the MS Kinect Sensor}, url = {https://m2.mtmt.hu/api/publication/2684494}, author = {Charles, K Toth and Molnár, Bence and Andrew, Zaydak and Dorota, A. Grejner-Brzezinska}, booktitle = {ASPRS 2012 Annual Conference}, unique-id = {2684494}, abstract = {Flash LiDAR systems have been around for several years, but their use was limited, mainly due to their poor performance. The first generation products had range limitations and were quite sensitive to ambient light conditions, basically restricting their use to indoor applications. In addition, the high-noise level provided for very low accuracy and stability. As technology advanced, the Flash LiDAR sensors have shown gradual improvements in performance, resulting in an increasing number of applications. One of the most recently introduced inexpensive sensors is the Microsoft Kinect, originally designed to support gaming. Despite its low cost, the Kinect is very powerful, providing a relatively dense point cloud and high-definition video at high data rate. This paper reports about our investigation with this sensor, including calibration experiences and performance evaluation.}, year = {2012}, pages = {538-546}, orcid-numbers = {Molnár, Bence/0000-0002-2602-2684} } @article{MTMT:2684910, title = {Accuracy Test of Microsoft Kinect for Human Morphologic Measurements}, url = {https://m2.mtmt.hu/api/publication/2684910}, author = {Molnár, Bence and Toth, C. K. and Detrekői, Ákos}, doi = {10.5194/isprsarchives-XXXIX-B3-543-2012}, journal-iso = {ISPRS (2002-)}, journal = {INTERNATIONAL ARCHIVES OF PHOTOGRAMMETRY AND REMOTE SENSING (2002-)}, volume = {39}, unique-id = {2684910}, issn = {1682-1750}, abstract = {The Microsoft Kinect sensor, a popular gaming console, is widely used in a large number of applications, including close-range 3D measurements. This low-end device is rather inexpensive compared to similar active imaging systems. The Kinect sensors include an RGB camera, an IR projector, an IR camera and an audio unit. The human morphologic measurements require high accuracy with fast data acquisition rate. To achieve the highest accuracy, the depth sensor and the RGB camera should be calibrated and co- registered to achieve high-quality 3D point cloud as well as optical imagery. Since this is a low-end sensor, developed for different purpose, the accuracy could be critical for 3D measurement-based applications. Therefore, two types of accuracy test are performed: (1) for describing the absolute accuracy, the ranging accuracy of the device in the range of 0.4 to 15 m should be estimated, and (2) the relative accuracy of points depending on the range should be characterized. For the accuracy investigation, a test field was created with two spheres, while the relative accuracy is described by sphere fitting performance and the distance estimation between the sphere center points. Some other factors can be also considered, such as the angle of incidence or the material used in these tests. The non-ambiguity range of the sensor is from 0.3 to 4 m, but, based on our experiences, it can be extended up to 20m. Obviously, this methodology raises some accuracy issues which make accuracy testing really important.}, year = {2012}, eissn = {2194-9034}, pages = {543-547}, orcid-numbers = {Molnár, Bence/0000-0002-2602-2684} }