| Maximum Likelihood processing time [message #38423] |
Tue, 09 March 2004 03:59  |
lbusett
Messages: 9
Registered: March 2004
|
Junior Member |
|
|
Hi all,
I need to evaluate the variation in the processing time required to
perform a maximum likelihood classification with a variable number of
input bands, so I'm using the ENVI built-in functions "envi stats
doit" (in order to compute ROI statistics) and "class_doit" (in order
to classify the image).
My problem is that when I perform the classification for the first
time I have a high processing time (i.e. 60 seconds), but if I perform
the same classification a second time, the time required for the
process is much lower (i.e. 10 seconds). I tried to reset the idl
session (with the .FULL_RESET_SESSION command), and also to quit and
restart idl and perform again the classification, but after the first
classification the time required for the process remains low. The only
way to have a comparable processing time is to restart my pc.
This also happens if I increase the number of input bands used: If I
make a classification with 10 bands, I have a high processing time,
but if I first make a classification with 5 bands and then a
classification with 10 bands, the time required for the 10 bands
classification is lower.
Does anybody know why it happens ? Is IDL (or ENVI) "storing"
somewhere the informations on previous calculations ?
I don't want to have to restart my computer every time I change the
number of bands in order to get comparable processing times....
Thanks for the help,
Lorenzo Busetto
Remote Sensing Lab.
University of Milano-Bicocca
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
