Appendix C

File Handling Table

The bulk of the time is spent in mosaicing images to composite a complete scene.  With large study areas this becomes a major component of the project which can be eliminated through use of other remote sensing platforms such as SPOT.  Where the cost of mosaicing is comparable to a purchase of SPOT imagery then the latter is recommended if available due to the reduced time for image processing.  A further saving in time is available where image downloading/uploading is not required and the processing hardware has adequate storage facilities (in the order of  greater than 5Gbytes).
 
PROCEDURE
TIME (Min)
FILE SIZE (approx)
% TIME (approx).
import single DMSV data file
10 
1.7Mb
  
 60 % 
 
save
1
1.7Mb
georeference single DMSV file
35 
1.7Mb
mosaic 350 files
240
410Mb
resample
150
190Mb
subset veg file
120
410Mb
  25 % 
subset water file 
120
410Mb
ISODATA classification
1500
410Mb
digitize vegetation mask
480
N/A
digitize water mask
240
N/A
digitize class polygons
1920
N/A 
create signature files 
10
N/A
edit signature files
480
N/A
edit raster colour attributes
40
N/A
supervised classification 
120
80Mb 
map
30
N/A
5%
postscript output
45
69Mb
DAT down/upload
240
2Gb
10%