This multi-camera system can be configured for almost any river mapping or monitoring operation. This system can be used to  record location of riverbank infrastructure, condition and vegetation.This system can be deployed from the air, river bank or by water vessel.

Advantages

    Inexpensive

    Cost effective

    Rapid data collection tool

    Advanced data processing & fast turnaround time of data

Applications

• River bank stability, vegetation survey, wildlife survey
• Engineering works planning
• Flood risk, defenses
• Waterway network navigation, tourism promotion
• Fisheries management

Image depicting positioning of object, (fish trap) from datum point onboard  

This system is constructed using two camcorders and one CamNav unit. Most high-street camcorders are suitable (Video8, S-VHS, Hi8, DV) as long as the camcorder has an external mic input to enable the GPS signal to be encoded on one of the audio tracks (normally two on standard camcorders). Alternatively, higher quality optical sensors together with DV VCR can be used. These have the advantage of higher quality images and longer play tapes.

Power consumption for this multi-camera configuration  is usually quite low and can be usually operated using batteries. A mount is normally constructed to maintain the cameras in a stable position inside the cabin or externally. This mount contains separate screw-in plates for each individual cameras. These can be adjusted enabling the camera to be rotated in pitch, roll and yaw. Usually, the higher the cameras are the better field of view (FOV). GPS encoded data is recorded onto each camcorder. A green light indicates that the GPS fix is good and recording is operating correctly.

Example of amulti-camera river browser

Schematic of multi-camera equipment for river mapping

Processing

The encoded data is processed using a frame-grabbing card and a suite of software located on a standard PC machine. The tape containing the encoded GPS is now decoded using the Camcorder, which is connected to the CamNav. Two output cables containing the video and GPS data are then connected to the frame-grabbing card and RS-232 serial port respectively. 

This is usually a two stage process. 

Processing - Stage One 

Frame-grabs frames at a rate chosen by the operator. These frames are tagged with GPS time and saved onto hard disk. At the same time, the GPS data is logged at the serial RS-232 port and saved in a file.

Screen-grab of the spatial video processing system.

Processing - Stage Two 

The second stage involves de-interlacing the digital video images and producing digital images 768*576 in size. An ESRI 'shape' navigation file is constructed from the logged GPS data. This file contains all the navigation data together with references to image names. It will take approximately 1.5hr of computer time to process one hour of spatial video data. Most of this time is required by the frame-grabbing module, which can only operate at normal video speeds.

The browser integrates the various video, GIS, database, measurement modules into an easy to use lightweight application. The main application window is split into video (right), GIS (left) and database (bottom left) displays. The user can load up any survey using the pull-down menus. A metadata layer is usually constructed beforehand and enables various surveys to be loaded with minimum fuss.

Screen-grab of a ‘basic’ browser system

The user can navigate through the spatial video data using the video controls, or by double-clicking on some point on the map or by clicking on a record within the database module. The video plays in the main video display as well as the three thumbnail displays. The position of the boat or vessel is dynamically displayed on a moving map. The usual pan/zoom/identify functions are available. Replay speed can be adjusted and various views can be turned on or off. Left or middle,  views can be chosen by clicking on the any one of the thumbnails below the main video display. Positions of river side objects can be measured using a perspective transformation algorithm  (based on a monoscopic camera model). This feature together with a data input module enables route objects to be entered into a database. Full spatial and imaging geometry of the object or feature are also stored. This allows the object to be quickly displayed later once the user double-clicks on the database record. This database together with associated video images can be easily exported to other mapping/imaging system and/or databases.

Additional products

Below is an example of a mosaic or strip-map compiled automatcically using 50 video frames of the River Yar (in association with Earthlinks)

CamNav Mapper™ Multi Camera Services

Blueglen prefer to work with the client to devise the most cost-effective and 'fit for purpose' solution for client's application. 

Acquisition

The client can acquire the CamNav Encoder/Decoder box and carry out the data acquisition themselves. Alternatively, BlueGlen can carry out any type of survey on your behalf.  Regardless, BlueGlen has a wealth of experience in choosing cameras, recorders, mounts, power distributionunits and can help the client decide on best options.

Processing

The multi camera processing suite can be purchased, rented or BlueGlen can undertake the processing on behalf of the client.  BlueGlen would provide remote or on-site support should the client purchase the processing module.

It is possible to setup a number of processors in parallel, to process multiple videotapes at the same time.

Browser

A single browser licence is included with a multi camera purchase.  Any number of extra licenses can be obtained or a corporate licence might be a more suitable option.

Normally a browser requires some customisation.

Level 1 Brow ser

Simple digital interactive map and GPS encoded video viewing system that allows the client to view data using PC based video control buttons and a 'moving map' display.

Level 2 Browser

Same as level 1 plus a database interface for data input, in-frame measurement, automated report generation, image processing functions.