Client's Shoreline & Coastal Webcams

Erdman Video Systems has years of experience monitoring the beach, park, and shoreline environments and has developed hardware, software, and strategies specifically for these goals. There are several ways to utilize Erdman Video Systems digital monitoring solutions in the coastal and tidal zones. A number of highly specialized image acquisition and processing tools are built into VM95, including ARGUS file format support.

Erosion	Restoration	Tourism

There are a number of features that we designed into our software that will benefit shoreline studies:

Streaming JPEG Sequences: The software handling the video signals can stream any of its video lines out to a browser or our dedicated application running under Windows. Streaming rates are usually limited by the bandwidth available. In a local LAN situation, streaming speeds depend on the processor power: typically on a 500MHz machine, streaming at 30fps is possible at 320x240, and 12 fps at 640x480. JPEG compression setting also affect this.

Image Averaging and Variance Computations: Image averaging and variance images are computed in real time by accumulating the pixel values of each frame, and accumulating the square of each value for the variance calculation. This is done at typical frame rates of 5 per second.

Pixel Data Extraction and Time Stack Creation: Up to 4096 points can be extracted from the video images in real time at rates up to 15 frames per second. Pixel data extraction can continue for over an hour, and at the end of the sampling period, a time stack plot is created from the data in the for of a bmp file. Embedded in this file is the time of each sample and the coordinatesof the points extracted. A utility program provided by EVS allows a text fileto be created from the bmp file which containsall the data in a form that can be easily imported into MatLab.

ARGUS File Format Support: ARGUS is a world-wide beach monitoring network developed and operated by the Coastal Imaging Laboratory (CIL) at Oregon State University, U.S.A. Snap, timex, variance and time stack images can be saved and uploaded following the ARGUS format so you can use their software directly on the uploaded imagery.

Long Exposures: Up to 15 second exposures can be programmed for night time imaging or for controlledlighting situations. For example, during the exposure, strobe lights (LED's can be triggered at various sequences.

Seek Exposure: Regions of the image can be selected for which the average brightness can be computed. By using seek exposure, the camera will take an image, compute the brightness in the selected region and adjust the exposure accordingly to obtain the desired level of exposure. This is an iterative process, but is very effective and accurate in low light scenes. Image stacking can be enabled by which multiple 15 second exposures are taken and summed (stacked) in such a way that the colors are perceived correctly. This is a technique developed in the astronomy field.

Burst Sampling: Five images taken in about 1.5 seconds can taken, downloaded to the computer, and archived to disk. This process can be repeated every 8-15 seconds depending on the capture resolution which impacts how long it takes to process and write the images to the media card. Optionally, this set of 'burst' images can be formed into an averaged image and a variance image.

Fastest Averaging Possible: Coastal Study projects often want an 'averaged' image, 10-20 minutes long, of near shore conditions in order to help identify shoreline position and also get an indication of where the submerged sandbars are, and where rip currents are most likely to be found. The faster images can be taken, the better the average comes out. Unlike video cameras, capturing from digital camera is slow, but the spatial resolution can be up to 20 times greater. The fastest speeds obtainable are about 1 image every 3-4 seconds for a resolution of 1024x768, and one image every 4-5 seconds for the highest resolutions. Averaged images formed this way for periods of 10 minutes or more appear very similar to those obtained using a video camera and faster sampling.

High Resolution Time Lapse (wmv file) Creation: Time lapse videos can be made automatically on schedule from any sequence of images. The sequences can be chosen from any scene and cover any interval of time up to the present. Selecting images at various intervals during the time period is also possible. For example, if you have images taken every 5 minutes for the past 6 months, you can make a video of hourly values covering the last 60 days of work.

For more detailed information see our applications page.