Re: [las_users] overriding subsampling

[Remon Sadikni <remon.sadikni@xxxxxxx>]

Hi Upendra, hi Ansley,

You could switch striding off in the ferret code. I did this for Time 
Series in LAS 7.1.2, by changing the code in 
/JavaSource/resources/ferret/LAS_initialize_variables.jnl in line 141 to

IF `($num)+1 EQ ($data_count)` THEN
   IF ($operation_service_action%|Plot_2D_XY>TRUE|*>FALSE%) THEN
           GO LAS_set_strides.jnl
   ENDIF
ENDIF

It works fine for me, so only for Plot_2D_XY (Maps) the script 
LAS_set_strides.jnl will be executed.

Regards,
Remon

On 06/10/2011 12:25 AM, Ansley Manke wrote:
> Hi Upendra,
> Subsampling is in LAS to prevent overly large data requests, and is 
> done in a way to try to minimize the effect on the end result. It is 
> not done for data downloads, only graphics.
>
> The Ferret scripts compute the amount of striding based first on the 
> amount of memory available to Ferret running as the backend. Next, 
> they compute the size in pixels of the output image and base the 
> amount of sampling on that - if there are 600x800 pixels then we won't 
> get a better 2D image by using full-resolution data that is larger 
> than that.  Time series plots may lose some extreme values of course, 
> so there's an argument for allowing control in some cases. If the time 
> series is being extracted from, say, an aggregation of many large 
> datasets, it can create huge requests, so one wants to think it 
> through. Allowing control that at the level of the LAS installer means 
> that you could decide when to turn this on or off.
>
> Right now there's not a way to override this in the configuration but 
> it could be added.  I'll write you off-line and we can talk about some 
> ideas.
>
> You're quite right that we need documentation that lists the Ferret 
> properties that can be used for customizing dataset configurations. 
> I've added an item to our to-do list to create that.
>
> Ansley
>
> On 6/9/2011 1:31 PM, Upendra Dadi wrote:
> > Hi,
> >  For some of the time series graphs, LAS puts the following on top of 
> > the graph "Subsampled x in T". How do I override subsampling and show 
> > the entire data? Is there a Ferret property I need to override? Also, 
> > is there a list of mapping between Ferret properties and the 
> > corresponding LAS XML tags. Please help. Thanks!
> >
> > Upendra