Two case study areas from different aggregate bearing geologies have been chosen to demonstrate the returns from different remote sensing techniques. The first area covers a sand and silicaceous gravel zone, where dessicating peat deposits are also present. The second area covers a sand and calcareous (chalk) gravel area, which is also dominated by windblown sand deposits.
In order to use the sample multi-spectral data, you will need to have access to a program which will read Imagine img files. Any of the following software packages will allow this, although none of them are cheap.
If you do not have access to one of the above programs you can download the free image processing software Open_EV from this website http://openev.sourceforge.net/, which is open source software allowing you to view and manipulate the multi-spectral images. As of the 27/02/2007, this was version 1.80, but updates to the software are being made all the time. You may need to download the FW Tools software (available from the same website) as well as Open_EV in order to harness the full functionality of the software. The instruction web pages in this section will be using Open_EV, but the other software packages mentioned above all have similar functions. However, each programme will use subtly different algorithms to perform linear stretch and equalisation functions on imagery, so if you are using a commercial package you may see slightly different results from the images displayed in the help files.
The multi spectral data is held on two files, called Site 005 1992_reduced.img and Site 020 1992_reduced.img. These need to be downloaded and saved to your hard disk before continuing with the next step. Although the images are georeferenced, these files have had the co-ordinate information removed, in order to protect the sites from illegal metal detecting.