viewing large data sets

[Mark Rehbein <mrehbein@xxxxxxxxxxx>]

Hi LAS people,

I've just finished setting up our LAS server to allow users to view our
satellite imagery.  It is currently behind our firewall so it is not
accessible to the world as yet.

Each image is 1600x1200 pixels for each day in time (1km resolution).

A problem occurs when a large lat/lon area is chosen.  LAS reports an
error from ferret:

dding an acceptable error string: "*** NOTE: ".
        NOAA/PMEL TMAP
        Program FERRET  
        Version 5.22 - 07/27/00
        15-Jun-01 11:46     

yes? cancel mode verify
yes? cancel mode interp
yes? canc data/all
yes? go std_initialize
"/u02/risdev/ferret/data/rs_sst.nc" "1" "1" "sst_ave"
yes? set
region/x="142.0":"155.0"/y="-27.0":"-7.0"/k=1/t="18-Apr-2001":"18-Apr-2001"
yes? set win/size=.5
yes? set win/asp=2
yes? GO "/tmp/lasgo22799352674.jnl"
 **ERROR: insufficient memory: 2603301 words were requested.
CONTOUR/FILL/levels=30/set sst_ave
Command file, command group, or REPEAT execution aborted


This is the same/similar error when you plot too many data points while
using ferret directly even after doing the set memory/size=xxx command.

I would like to ask if anybody has overcome this problem as the last thing
I want is for users to get freaked out simply because they chose such a
big area.

A solution might be to automatically reduce the resolution (ie pick every
4th pixel) when an arbitary large number of data points are chosen.  Not
sure how to do this though using LAS.

Any help/suggestions would be appreciated. 

cheers

mark

Mark Rehbein
Intranet Developer
Australian Institute of Marine Science