There are a number of different image types that are collected by the ARGUS coastal imaging system.
The simplest image type is the snap-shot image. This is the same image that you would see if you took a picture of the beach using a conventional camera. Snap-shot images provide simple documentation of the general characteristics of the beach, but they are not as useful for obtaining quantitative information.
A much more useful image type is the time-exposure image. Time-exposure images are created by the ‘averaging’ of 600 individual snap-shot images that are collected at the minimum rate of 1 picture every second, for a period of 10 minutes. A lot of quantitative information can be obtained from these images. Time-exposures of the nearshore wave field have the effect of averaging out the natural variations of breaking waves, to reveal smooth areas of white, which has been shown to provide an excellent indicator of the shoreline and nearshore bars. In this manner, a quantitative ‘map’ of the underlying beach morphology can be obtained.
At the same time that the time-exposure images are being collected, max (below left) and min (below right) images are also created. Whereas the time-exposure is an average of many individual snap-shot icons, the corresponding max and min image display the maximum and minimum light intensity during the period.
In place of max and min images, the older Argus II stations collect variance images (below), the ”variation” of light intensity during the same 10 minute time period. The max, min and variance images help identify regions which are changing in time.
Snap-shot, time-exposure and max and min (or variance) images are automatically created every hour or half hour at the remote camera site, and the images transferred to WRL for archiving and analysis. Analysis tools include the ability to rectify images to real-world coordinates, merging of images from multiple cameras to produce a single plan view image, and the mapping of the shoreline, bars, rips and many other features of the coastline. More information about this is provided in the image analysis section of this website.
