[IDV #MQM-696970]: visad error propagation facility

Hi Tyn-

> Thanks, sounds wonderful.

No problems.  It's more complete this way.

> According to this example Tom provides the variable should already have an 
> error attached before an operation is preformed (see first two lines):
> 
> a = new Real(10.,1.);
> b = new Real(255.,10.);
> c = (Real) a.add(b, Data.NEAREST_NEIGHBOR, Data.INDEPENDENT);
> System.out.println("sum = "+c);
> System.out.println("error of sum is="+c.getError().getErrorValue());
> When you run this example, you get:
> sum = 265.0
> error of sum is=10.04987562112089
> 
> How do I provide the error FieldImpl along with the FieldImpl, should this be 
> done before I perform sampleToReal?

When you call setSamples on the FieldImpl, you would pass in the ErrorEstimate. 
 I'll have to get more info on what that will look like.  

> As i wrote earlier: I have a seperate error-field along with the FieldImpl i 
> do the GridUtil.sampleToReal on. The two FieldImpl share the same 
> time-dimension as they're from the same ADDE imageSeq.

So, do you have an error value for each point in the image?  Or is it an error 
per image?

Don

> -----Original Message-----
> From: Unidata IDV Support [mailto:address@hidden]
> Sent: Tuesday, February 23, 2010 5:24 PM
> To: Valentijn Venus
> Cc: address@hidden
> Subject: [IDV #MQM-696970]: visad error propagation facility
> 
> Hi Tyn-
> 
> > Further to my previous message, I already found some answers to some of my 
> > questions. However, can you comment on the ??? below.
> >
> > > What are the numerical equivalents for the other propagations methods to 
> > > set int errorMode correctly?
> >
> > Data.NO_ERROR    = 202
> > Data.INDEPENDENT = ???
> > Data.DEPENDENT   = ???
> 
> Data.INDEPENDENT = 200
> Data.DEPENDENT   = 201
> 
> I've added the following to GridUtil so you can use them there:
> 
> public static final int NO_ERRORS = Data.NO_ERRORS;
> public static final int DEPENDENT_ERRORS = Data.DEPENDENT;
> public static final int INDEPENDENT_ERRORS = Data.INDEPENDENT;
> 
> I've also added an error mode to the sampleToReal. sample already had the 
> error mode signature.
> 
> These will be in tomorrow's build.
> 
> > http://www.unidata.ucar.edu/software/idv/docs/javadoc/constant-values.html#ucar.unidata.data.grid.GridUtil.DEFAULT_ERROR_MODE
> >
> > > Is there a javadoc showing all propagations methods?
> >
> > NO, except this snippet in 
> > http://www.unidata.ucar.edu/mailing_lists/archives/visad/2002/msg00170.html:
> >
> >
> > > Also, I can see that Data.INDEPENDENT uses a linear 'error
> > > propagation' algorithm, but what does actually Data.DEPENDENT do (doesn't
> > > one need to know the functional form of the dependency?). Is there any
> > > auxiliary documentation somewhere, or references to the algorithms used?
> >
> > For Data.DEPENDENT the system uses the worst case error
> > propagation, where they are simply added. This is essentially
> > interval arithmetic. For Data.INDEPENDENT the system uses
> > root mean square error propagation.
> 
> I don't know any more than what was in that message.  As Bill pointed out, 
> this has not been tested very well. I have no experience using the error 
> propagation, but if you run into problems, we can muddle along together. ;-)
> 
> Don
> 
> > -----Original Message-----
> > From: Unidata IDV Support [mailto:address@hidden]
> > Sent: Wednesday, May 13, 2009 12:25 AM
> > To: Valentijn Venus
> > Cc: address@hidden
> > Subject: [IDV #MQM-696970]: visad error propagation facility
> >
> > Hi Tyn-
> >
> > > thanks!
> > >
> > > Unfortunately, not everything is done with visad.
> >
> > It will be difficult to do the error propagation fully then.
> >
> > > On the IDV side, would it take a lot of work to for all methods to pass 
> > > an error propagation type other than Data.NO_ERROR? Do you think Willem 
> > > could handle such a task?
> >
> > You'd need a way for the user to set the error mode and then modify all the
> > methods in GridUtil that take a sampling method to also take an error mode.
> > I took a stab at the latter, but not sure I got all the methods yet.  Then
> > any of the controls/methods that do sampling would need to implement this
> > as well.
> >
> > I'm sure there are other gotcha's out there.  We're in the middle of
> > finalizing the 2.7 release, so don't have time to work on this.  If
> > Willem wants to look into it I can try to answer some of his questions.
> >
> > Don
> >
> >
> > Ticket Details
> > ===================
> > Ticket ID: MQM-696970
> > Department: Support IDV
> > Priority: Normal
> > Status: Open
> >
> >
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> > Faculty of Geo-Information Science and Earth Observation (ITC)
> > University of Twente
> >
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> 
> Ticket Details
> ===================
> Ticket ID: MQM-696970
> Department: Support IDV
> Priority: Normal
> Status: Open
> 
> Faculty of Geo-Information Science and Earth Observation (ITC)
> University of Twente
> 
> E-mail disclaimer
> The information in this e-mail, including any attachments, is intended for 
> the addressee only. If you are not the intended recipient, you are hereby 
> notified that any disclosure, copying, distribution or action in relation to 
> the content of this information is strictly prohibited. If you have received 
> this e-mail by mistake, please delete the message and any attachment and 
> inform the sender by return e-mail. ITC accepts no liability for any error or 
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> 


Ticket Details
===================
Ticket ID: MQM-696970
Department: Support IDV
Priority: Normal
Status: Open