Showing posts from May 15, 2008

Why do we use a Geographic Information System?

In a recent post we described how we manually converted a high-resolution aerial image mosaic of the Bermuda reef platform into a set of georeferenced polygons - creating a digital map of all the reefs around the island.

There are many benefits to having an electronic map instead of a paper map.

When each patch reef was added to the database, they were each assigned a number. This means every single patch reef in Bermuda now has a unique ID tag that can be used to name them.

In this section of the aerial image, abouto 1km wide,
you can see the ID number of each patch reef.

Having an ID number for every reef helps scientists and resource managers, as it gives another way to distinguish each reef.

Proximity Mapping
Wecan ask the GIS programme to select reefs within a certain distance of another mapped object. For instance, if we have a layer representing the Island, we can ask the programme to select and highlight all of the reefs that are within 1 nautical mile from shore. This then …