An Aerial Photography - Aided Seaweed Bed Survey Techniques
Yoshio Matsumoto, Eiji Yamauchi, and Koji Kamihashi
Asia Air Survey Co., Ltd.
Abstract
The used aerial photography in seaweed bed distribution surveys has become widespread in recent years. One of the advantages of the use of aerial photography in surveys is that it allows for a wick, economical appreciation in surveys is that it allows for a quick, economical appreciation of the distribution of seaweed beds extending over a wide area.
In the following, we shall introduce the analytical photographic techniques we use in compiling seaweed bed distribution charts classified according to seaweed bed type based on aerial photographs.
Introduction
Seaweed beds play an important role in the reproduction of marine resources; the benthic marine algae they are made up of are themselves an important natural resource, and moreover they function as nursery grounds and habitats for fish larvae of shellfish.
These important functions of seaweed beds are influenced by the type, distribution density, and distribution acreage of the benthic marine algae that make up the seaweed beds, so it is of utmost importance to gain and understanding of these factors through seaweed bed surveys.
In conventional seaweed bed surveys, the methods of observation through a glass box from a boat and direct observation by labor and time when a vast sea areas is to be surveyed. To overcome these difficulties, the utilization of vertical color aerial photography has become more and more prevalent.
Today, we apply the following three techniques for photographic analysis in compiling seaweed bed distribution charts from vertical color aerial photographs :
- Reading photo by eye :
- Digital image processing
- Analog image processing (masking method)
The following we will provide an outline of each photo analytic technique and a description of its characteristic features.
