Video Beach Monitoring of Shoreline Change ("Cam-Era")

Computer-controlled video cameras monitor the environment (for data collection and research) while simultaneously providing images for beach-goers, such as surfers and swimmers. A series of cameras has been established since this project started in August 1997. There are three cameras on the Coromandel coast, overlooking Tairua and Pauanui Ocean Beaches. The sand spit at Mokau is experiencing significant long-term coastal erosion. Cameras were placed at Mokau Spit to monitor changes in the beach and river mouth/bar. A Master of Science study was initiated to utilise images gathered to isolate the natural processes controlling spit dynamics and the time scales over which they occur. Data was collected at Mokau from 1999 until 2007. In 2007 a new camera site (two cameras) was established at Raglan. Each hour, cameras at Pauanui, Tairua and Raglan automatically collect images which are then archived (for subsequent research purposes) and placed on the Web for public use. The cameras provide data for research into beach processes. The images can also be used for monitoring beach state, shoreline position, beach use, wave conditions, bar conditions and rip currents. The project is a collaboration between Waikato Regional Coucnil and NIWA.

Every hour during daylight time, 600 images (one every second for 10 minutes) are taken. The first of the 600 is saved as an individual image and posted on the website. The 600 images are averaged and saved as one image, which is also archived.

Two cameras at Pauanui (north and south end), one on Paku Hill overlooking Tairua Ocean Beach. Two cameras at Mokau (one camera looking over river mouth and offshore bars, the other along the foreshore - site disestablished in 2007). Raglan (two cameras) established in 2007.

Tairua Camera: August 1997 - present Pauanui A & B: December 2000 - present Mokau A & B: June 1999 - 2007 Raglan A & B: 2007 - present. Mokau RTK-GPS survey 22/12/03, 22/03/04, 5/07/04 and 15/12/04.

Images are collected hourly and displayed on the Waikato Regional Council website and NIWA website. See links below. Cameras at the remote sites are mounted on poles or on buildings overlooking the monitoring site. The cameras have rain hoods and lens-washers to improve image quality. Each site must have a power supply, a computer to control the system and a phone connection so that it can communicate with the base station in Hamilton. The Mokau site has the remote computer housed in the Mokau museum away from the camera, with a radio link connecting the two. Further details are given at NIWA link below.

There are a number of image processing techniques required to make use of the image for many purposes, including: Averaging: Some information that can be obtained from the images is not apparent from an individual image. For example, to find the position of the shorlein or offshore sand bars (from breaking wave patterns), 16 minutes of images (600 images) are taken every hour an can be averaged. In the resulting image, the average shoreline and average position of the bar become clearly visible. Rectification: the rectification routine takes an oblique image and converts it to a plan view by mathematical transformation using the orientation and position of the camera. Once the oblique images are rectified, the images become the equivalent of a vertical aerial photograph, which allows direct scaling of features such as high water marks and rip currents. Lens distortions: for detailed measurements (e.g. measuring wave parameters) distortions caused by imperfections in the glass and the way the surface is shaped need to be corrected. These distortions have been corrected using freely available software written by Janne Heikkila at the University of Oulu, Finland (Heikkila and Silven 1996). There are occasional gaps in the data when cameras or housings have been damaged. Complicated aspects of data quality are available in the many publications listed here. Some gaps are present in the data record due to equipment failure and camera maintenance. Some images at Mokau are of poor quality due to light levels, sun angle and the quality of the radio link.

Digital images, including individual and averaged images. Averaged images are also rectified and may be available in some cases - contact NIWA.

Coastal processes research and beach monitoring.

Not confidential but contact data owners

Study ongoing as described above

Cameras at Raglan, Tairua and Mokau owned by Waikato Regional Council. Cameras at Pauanui owned by NIWA.