Coastal Aerial Video Imaging (AVI) Surveys

Coastal & Ocean Resources Inc. (CORI) has conducted more than 70,000 km of coastal video imaging surveys during the past 10 years in support of coastal habitat mapping and oil spill response operations. These surveys involve the collection of oblique aerial video imagery (Fig. 1) from either a fixed wing aircraft or from a helicopter. The surveys are generally weather- independent and excellent imagery has been collected in rainy conditions. Image collection procedures vary based on client applications, but surveys are typically collected at 100 m altitude and flight speeds of 60 knots. Imagery is usually flown at low tide and often provides the only available images of the entire intertidal zone (most conventional aerial photos are often taken at high tide). We typically image 300 to 350 km of shoreline during a 3-4 hour low-tide window.

Figure 1 Image capture of aerial video image of Friendly, Nootka Island showing the latitude, longitude, and UTC time that is burned onto the image during the overflight.

Figure 2 Typical helicopter imaging set-up – door removed, communications head-set, and Sony Hi8 .DX3 camera.

 We have developed high-resolution coastal mapping systems that take utilizes video and digital still imagery in which features as small as cobbles can be discerned, as well as the zonation of intertidal algae and other biota.

CORI maintains a complete video imaging system, including Hi8 cameras and recorders (Fig. 2), DGPS positioning systems for continuous in-flight location logging, a captioning unit for burning GPS position onto the video image during the overflight (Fig. 1), and communication systems for recording two synchronous in-flight commentaries. Lap-top moving map systems are linked to the GPS system record in-flight position at one second intervals (Fig. 3) and to show location of the flight path in real time. Hi8 editing systems provide a convenient means of post-survey editing and copying of the imagery - the original Hi8 tapes are usually mastered to SVHS tapes to provide a high-resolution working copy.

The highest resolution imagery is collected from helicopters, but the system has also been used in fixed wing Cessnas, Beavers, Twin-Otters and Helio-Couriers.

Figure 3 Flightline track based on 1-second GPS fixes.

 

Published references on aerial video imaging standards and mapping systems developed by CORI:

Harper, J. R. and P.D. Reimer 1995. Review of aerial video survey techniques and recommendations of survey standards. Contract Report by Coastal & Ocean Resources Inc. of Sidney, BC to the Resource Inventory Committee of the Province of British Columbia, Victoria, BC, 38p.

Harper., J.R. and P.D. Reimer 1995. Review of aerial video imagery (AVI) applications and development of AVI standards for the Province of British Columbia. In Proceedings of the Third Thematic Conference on Remote Sensing for Marine and Coastal Environments, Seattle WA, p. 700-709.

Morris, M., J.R. Harper , P.D. Reimer, H.R. Frith and D.E. Howes 1995. Coastal biotic mapping system using aerial video imagery. In Proceedings of the Third Thematic Conference on Remote Sensing for Marine and Coastal Environments, Seattle WA, p. 200-210.