CU-VIDEO TRACKER: QGIS PLUGIN FOR VIDEO TRACKER

Transcription

1 CU-VIDEO TRACKER: QGIS PLUGIN FOR VIDEO TRACKER Suchawadee Sillaparat 1 and Sanphet Chunithipaisan 2 1 Graduate Student, Department of Survey Engineering, Chulalongorn University, Bangkok, Thailand chadee.silla@hotmail.com 2 Assistance Professor, Department of Survey Engineering, Chulalongorn University, Bangkok, Thailand sanphet.c@chula.ac.th KEY WORDS: GIS, Video, QGIS, Plugin, tracker ABSTRACT: In recent years, video camera is widely used in Thailand to capture events for various purposes e.g. car cameras and drone camera. Many of video cameras integrate with GPS data. Such data would be very useful for updating GIS database if video itself can be visualized with logging positional data fr om GPS through georegistered visual and audio records. This paper reports the development of CU-video tracker plugin in QGIS which enable video can be visualized with logging traveling path from GPS data. This plugin is adapted and extended from Video UAV Tracker QGIS Plugin in order to use with a delimited text file. The interpolation of logging time and position of traveling path to link with video frame is supported. The creation of landmark responding to the video scene is provided via location identifying on screen and/or video frame snapshot. Sample data from car camera and drone camera are tested. This developed plugin can help GIS users earn more benefits from video data together with tracking data associated for updating GIS database 1. INTRODUCTION Recently, the most camcorder are mounted with GPS and enabled the linkage between video and GPS. Most videos present only graphic without position of such video (Hak Joo and others, 2004). If video can be visualized with its traveling path on GIS and snapshot of video can be gotten with its location, this will be very useful for GIS people to make use this media for updating GIS data. Quantum GIS is free popular software in open source software (Keawseekao, 2011) and has the ability in processing of both vector and raster data. In addition to the main feature of program, the user is able to create the additional tool as plugin with Python language to add in the program. Generally, the data of log file which come from GPS-mounted camcorder has the different data collection depends on manufacturer (QgisProject, 2014) such as car camera, drone camera and mobile application that collect many kinds of data such as latitude, longitude, elevation and timestamp. Sometime log file would not record timestamp data that is the important data in linkage of video and taking position. This paper purposes the research which applies Quantum GIS to display the linkage of video and its position in GIS using logging data. This development adapted the plugin Video UAV Tracker which it is the plugin used in video display together with flight path from UAV (Agosta, 2012). This research uses with log file in delimited text format to calculate the linkage of the position in logging data and video frame. Time offset of each logging position is calculated by assuming that log file is recorded in equal time interval. Besides the plugin which can show the video along with its position from GPS, it is also able to create data layer to record the interested position and image to update spatial data. 2. METHODOLOGY The objective of this research is to develop GIS tools for linkage between video and tracking data with the concept that timestamp is used in linkage process (Johansen, 2006). However, sometime log file does not record timestamp data. Therefore, it is not able to link video with tracking data straightforwardly. Time offset is then to be used instead of timestamp by using logging interval to get time offset in order to support and enable the linkage of video data with log files.

2 Log File Timestamp No Timestamp Logging Interval Time Offset Figure 1. Method of log file 2.1 Logging Interval Data logging interval can be calculated from the number of recorded data on the assumption that the logging data coincides with the media recording and uses the same period for each log. Therefore, logging interval can be derived from the total time of video and number of point in logging data. P 3 P 4 P 5 P 2 P 6 P 1 P 0 Number of Point = 8 Number of Range = 7 P 7 Figure 2. Number of Point and Range Logging interval = Where T N 1 T = Total time of video (seconds) N = Number of Point in log file 2.2 Time Offset Time offset is the accumulation model of time interval from the first point to the last point of recording data. Time offset starts at 0 to the time of video. Time offset will be a part of attributes of logging position data which used to link with the video. n 1 Time Offset = i P i x Logging Interval Where P = Point number in log file n = Number of Point in log file i = Point number starts at 0 to n-1

3 2.3 Linking video data with tracking The linkage between video and tracking data is the link between time of video and time offset calculated from logging data. The starting frame of video is associated with the starting point of tracking, and the last point of tracking is mapped to the last scene of video Time Interval = 1 Time offset = Video time (Second) 2.4 Plugin for visualizing and capturing data POINT LATITUDE LONGITUDE TIMESTAMP TIME OFFSET Figure 3.Concept of linkage between video and track The tool for visualize video with tracking path in GIS was developed in the form of plugin on Quantum GIS. The video visualized with tracking path can be done through the attribute of time offset. The capturing tool to create point of interest from video and location from tracking path was created to get the video snap shot and its location. This captured data is stored in another temporary GIS layer and can be exported into comma delimited format which can be used in other GISs. Figure 4. The functional design of plugin 3. RESULT 3.1 Data Video and log file used in the test of plugin are from car camera and drone camera as following;

4 3.1.1) Car camera The testing data from some car camera was taken to test the plugin, and its log file includes latitude, longitude and timestamp as shown in figure ) Drone camera Figure 5. Video ang log file from car camera Another testing data was from drone camera. Log file contains only latitude, longitude and no timestamp as shown in figure 6. Figure 6. Video ang log file from drone camera 3.2 The result of the linkage between video and tracking Testing results have clearly shown the visualization of video with tracking point along the path representing the location corresponding with video data. The capturing location and snapshot of video were also tested in both selecting from the position and video to get the picture and its coordinate. The results shown in form of coordinate of the location and the picture taken from selected location. The snapshot images are stored in the specific folder, and the path of image is stored as an attribute in point attribute table. These captured data can also be exported into CSV format in order to reopen in other GISs.

5 IMAGE Figure 7. The result of the linkage between video and tracking 4. DISCUSSION AND CONCLUSION This plugin is developed in order to increase benefit from the vehicle camera which is more popularly used in Thailand. Presented plugin aims to people who need tools for accessing video with GIS. In addition to view video, it can be used to support updating GIS data such as landuse or infrastructure along the line. Most vehicle camera with GPS records latitude and longitude in its logging data. These data can be viewed in GIS through this plugin. Any point of interest along the path can also be captured to get the snapshot of defined location. REFERENCES Hak Joo I., Hyun Hwang T. and Ho Choi K., Generation of video metadata supporting video GIS integration. In: International conference on Image Processing (ICIP), Korea. Johansen D., Video stabilization and target locationlization using feature tracking with small UAV video, United State. Keawseekao A., Development of video image tool on Quantum GIS. In: The 18 th National Convention on Civil Engineering (NCCE), Thailand. QGIS Project, QGIS User Guide: Working with GPS data, pp.153 Agosta S., Video UAV Tracker., Retrieved December 10, 2014, from /plugins/video_uav_tracker/