<simboss> ciao mbedward
<simboss> or michael
<mbedward> hi simone, andrea
<mbedward> I'm not sure how to start - do you have something you would like to begin with
<aaime> Is this a meeting?
<mbedward> no just a chat
<mbedward> about jai-related things
<simboss> well, the floor is yours
<simboss> daniele is coming
<simboss> not sure if antonello is around
<simboss> looks like is not
<simboss> checked on the udig channel
<mbedward> I can wait a few minutes - that's no problem
<simboss> if you did not sent around a reminder
<simboss> it might be that he has forgotten
<mbedward> yes - I'm afraid I forgot about reminding anyone
<mbedward> perhaps we can just start chatting - we can always go back if he joins us or rehash later
<aaime> if you want any chance of him showing up send a mail to him and Silvia
<mbedward> ok, I'll do that now
<moovida> morning folks
<moovida> thanks for the email
<mbedward> no worries
<moovida> I was working on a bug and forgot
<moovida> what did I miss?
<mbedward> we haven't started
<moovida> oh, great!
<mbedward> we couldn't start without you !
<mbedward> perhaps I'll begin my just describing my immediate project needs that have led me down this path
<moovida> good for me
<mbedward> for an app that I'm working on at the moment I need to be able to do two things
<mbedward> 1. allow a user to create a grid coverage based on mathematical expressions
<mbedward> where the user just provides a relatively simple script
<mbedward> and the expressions have spatial position and/or other coverage data as inputs
<aaime> just for the record, Sextante has some raster algebra support built-in
<mbedward> ok - I'd be interested to hear about that in a minute
<moovida> mbedward: what do you mean by: the expressions have spatial position?
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<mbedward> basically functions of x,y coords
<moovida> not row/column, but instead coordinates?
<mbedward> could be row/col, or proportion of width/height etc
<moovida> can you make an example in which you would want to use coordinates inside an expression?
<moovida> ah, ok, got it, wanted to be sure
<mbedward> sure: my app is about animals in landscapes
<mbedward> responding to various resources
<mbedward> imagine I want to create an artificial resource map
<mbedward> with a north-south gradient
<mbedward> I might do that with a simple linear function plus a noise component
<moovida> ok, nice
<moovida> so you are talking about functions really or more neighbour cell touching?
<moovida> I mean you won't be able to embed a function based on position in a static approac
<moovida> you will have to use relative positions between cells?
- moovida has difficulties to explain himself
<moovida> so the gradient will be based for every cell on values of the cells around it
<moovida> is that what you mean by function?
<mbedward> that's not what I was think about in the example...
<mbedward> although neighbourhood stuff certainly comes in lates
<moovida> ok, good, how would a hipotetic function look like?
<moovida> you have an idea already?
<moovida> the linear function for example
<mbedward> value = xpos * alpha + beta + random(sigma)
<mbedward> where xpos could be position along coverage axis scaled as 0 -> 1
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<moovida> sounds good
<mbedward> so very simple
<mbedward> this was the idea behind 'jiffle'
<mbedward> the ANTLR grammar that I'm fiddling with
<mbedward> it's essentially a simple expression evaluator
<mbedward> I've put the current ANTLR parser and tree grammars on to the project site
<mbedward> they are very preliminary but maybe give you some idea when you look at them
<mbedward> but it isn't joined to images yet
<mbedward> now that I've got basic arithmetic, trig functions etc in jiffle
<mbedward> the next thing I'd like to do is work out how to plug input image data into the interpreter
<mbedward> I was interested in the r.mapcalc page that you pointed me to yesterday
<aaime> again for the record, what about Janino? http://www.janino.net/use.html It can be used to compile expressions into bytecode. Makes the evaluation very fast
<moovida> r.mapcalc is what I will need and for which I could work
<mbedward> I don't know this at all - would be very interested to know more - have you used it ?
<moovida> and I think it contains also what you need
<moovida> so, how could I/we help you?
<mbedward> you mentioned that you were using jep previously ?
<aaime> sextante does too
<aaime> (use jep)
<moovida> yes, I did for a while
<moovida> but it is now closed source
<moovida> and so I would not want to use it any more
<moovida> or better, I do not use it any more
<aaime> yep, that's why I looked into janino a little bit, to suggest Sextante an escape route
<mbedward> I understand jep was highly optimized
<moovida> yes, it was, but from that moment on they closed the source
<mbedward> at the moment speed is less important for my needs than just ease of use and flexibility
<mbedward> and having something that I can understand !
<moovida> ok, but you would not want to use jep, right?
<mbedward> what are your r.mapcalc needs ?
<mbedward> no - I want to use open source
<moovida> my needs are well inside yours
<moovida> functions would be great
<moovida> because they contain also functions based on several maps
<moovida> and conditions are important
<moovida> things like:
<moovida> if in map1 the value is null, do that, else take value from map2
<moovida> but I think on this we have the same ideas
<moovida> so one question from an ignorant antrl person
<moovida> antrl is used as a functional language "compiler"?
<moovida> and then you need something to evaluate the transformed language?
<mbedward> it is general parser building tool
<mbedward> similar in aim to lex, yacc, bison...
<mbedward> for example
<moovida> ok, so thorught that you get your java language for the math you write
<mbedward> you can
<mbedward> or C, or python or other things
<mbedward> it can be used to build a translator
<mbedward> but what I am interested in is an interpreter
<mbedward> so two steps...
<mbedward> first provide a grammar that describes the language elements (similar to EBNF)
<mbedward> from this ANTLR helps you to build a lexer and parser that can accept language statements
<mbedward> detect syntax errors
<mbedward> re-arrange things for faster processing
<mbedward> the output of this first step is a tree representation of your input statements
<mbedward> Abstract Syntax Tree in the jargon
<mbedward> second step is to build a 'tree-walker'
<mbedward> this knows how to take navigate the tree-representation of your 'program'
<mbedward> and you can embed the code for actions into the walker
<mbedward> that's a really terrible explanation )
<mbedward> I'll give an example
<moovida> I understand, the JGrass console is built like that
<moovida> now I am very sorry we didn't use antrl
<mbedward> antlr is really cool
<mbedward> I'm only learning
<mbedward> but it is possible to get quite a bit done in a small amount of time
<moovida> the developer created an own compiler, and now every time I have to changes something, I get mad
<moovida> yes, that was my feeling of antrl
<moovida> sound really good
<mbedward> in the past I've written parsers by hand and this is **much** easier
<moovida> what timeline did you think of for this?
<moovida> also, were are you based?
<mbedward> I'm already very late
<mbedward> I'm in Sydney
<moovida> argh, I found one in London and thought we could meet for an initial push
<mbedward> I think he works for the BBC
<mbedward> I saw his name on TV once
<moovida> hmmm, then let's get back to the timeline, Sydney is out of budget for this project
<moovida> just to understand if we could coordinate
<moovida> I also have to study antrl first
<moovida> so it would be good to see if we are at least a bit in sync
<mbedward> well, it's very fuzzy for me and there are many strands to my project that I can also work on when it's not convenient to be in sync
<mbedward> sync in time I mean
<mbedward> there are good intros on the antlr site
<moovida> great, I'll check them out
<mbedward> I want to find a good starting approach for inputting image data into the interpreter...
<mbedward> r.mapcalc had the simple convention of var names
<mbedward> if not functions etc. they were assumed to be maps - is that right ?
<moovida> yes, and keeping those would help me get JGrass -> GRASS compatibility
<moovida> yes, exactly
<mbedward> I was thinking of something slightly more indirect
<mbedward> though it might still be compatible
<moovida> users have huge scripts for mapcalc to do the most powerfull things
<mbedward> I thought that would be the case
<mbedward> so it would be great to be compatible
<moovida> good you think so
<moovida> at least to start like that
<mbedward> I want to keep this all as modular as possible
<moovida> then there are always possibilities to get out of compatibility
<moovida> what do you mean?
<mbedward> well the interpreter is one module
<mbedward> it 'knows' (will know) how to access data from some provider interface
<mbedward> but the provider implementations could be quite diverse
<mbedward> my thinking is very fuzzy...
<mbedward> in r.mapcalc is there any sort of definition section for variables / inputs
<mbedward> or do they just appear in statements ?
<moovida> I don't understand exactly what you mean
<mbedward> is there anywhere in the script where you have to declare var names prior to using them ?
<moovida> you can have also variables evaluated in steps and then used inside the script
<moovida> no, var=eval() is enough
<mbedward> I need to go study r.mapcalc while you look at ANTLR
<moovida> then we have a sort of plan
<mbedward> yes !
<moovida> even if I feel it will take me some longer
<moovida> the mapcalc module can do very complex things
<moovida> did you think to make a constatly usable progress?
<mbedward> definitely !
<moovida> I mean, start to work and get a version that supports some functions and son and on?
<mbedward> otherwise giant mess !
<moovida> great, that sounds good
<moovida> same for me here, and also the project then can grow
<moovida> slowly and stable
<mbedward> there is also a second strand to this work - JAI operators
<mbedward> especially for neighbourhood map calculations
<mbedward> I need to be able to do the sort of things that, in the old, old days I might have done in arc-info
<mbedward> esp. focal functions
<mbedward> e.g. average neighbourhood value, dominant value, number of discrete values...
<mbedward> I was a bit surprised that these were not already in JAI operators
<moovida> are you sure there aren't?
<mbedward> also being able to constrain these and other calculations with mask / ROI
<moovida> sounds strange to me also
<mbedward> I think some of these things could be useful to geotools etc. generally
<mbedward> and I would like to open source my code for new operators
<mbedward> so I plan to put them on the jai-tools site also
<moovida> seems to be a lot of work to be done
<moovida> what was your schedule again?
<mbedward> I'm very very late
<moovida> for yesterday or so?
<mbedward> but I am also the project manager
<mbedward> unfortunately the project does not have enough money to employ a real programmer...
<mbedward> so an ecologist is doing the job
<moovida> ecologist and environmental engineer
<mbedward> obviously there is overlap between ANTLR side and jai-operators side
<moovida> any other person that wants to join the brigade?
<mbedward> I think / hope simone is interested in the jai operators strand
<moovida> simboss, dany_r ? What about you guys?
<dany_r> yes he's interested
<moovida> mbedward: just to have an idea, you need a version that does x,y,z for date a,b,c
<moovida> can you tell about x,y,z and a,b,c
<moovida> if you are allowed, and just a more-or-less
<moovida> is enough
<mbedward> yep, roughly anyway...
<moovida> this job is resources absorbing and if I help I want to be able to really do so
<mbedward> in next month I would like to have the scripting working to the point where
<dany_r> our aim would be allowing handling, chaining math operations and functions in JAI operators.
<mbedward> it can do arithmetic and basic math/trig functions already in grammar
<mbedward> plus conditional expressions
<moovida> hmmm, I guess that will not be exactly the case
<moovida> am I right?
<mbedward> and access data from input images
<mbedward> (will get to that in a sec)
<moovida> doing it mbedward's way will mean that no chaining occurs?
<mbedward> if I can get that working by end of Feb that would be very good for me
<mbedward> ok - in terms of output
<mbedward> I have thought about two approaches, each of which I'd like to implement
<dany_r> in this right moment Simone is not here but he can provide you more details about its idea very soon.
<mbedward> first is interpreter produces output that can be linked to a JAI image function
<moovida> sorry guys, I have to run, could anybody post the logs, or send me the logs, if much is said after this moment?
<mbedward> no worries
<moovida> mbedward: I am very interested to join the efforth, but I have to understand if I am ablr to contribute that early
<moovida> to do so, I will study antrl in the next days
<moovida> and study what you already did
<mbedward> you can then tell me all the mistakes
<moovida> would be glad to
<moovida> and let's keep the discussion in the list active please
<mbedward> will do
<moovida> thanks for the chat
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<mbedward> dany would you like to keep going when simone comes back ? or I can pen some thoughts and send them to you...
<simboss> ciao michael
<simboss> I am back
<mbedward> ciao simone
<simboss> sorry, but I have someone here, so I had to talk to him
<simboss> I am all yours now
<mbedward> I think we were only just getting to teh things you are most interested in
<mbedward> jai operators plus
<simboss> ah great
<mbedward> possibility of using an interpreter to help make image functions etc.
<simboss> well, at this stage
<simboss> my interest is in having a good project
<simboss> where we can drop JAI operators
<simboss> so that we can releases
<simboss> in a more stable manner
<simboss> JAI is not dead
<simboss> but it's a zombie
<mbedward> why has that happened ?
<mbedward> it's hard to understand
<simboss> the members of the prject are heavily involved in other projeects
<simboss> well, it's simpler than it seems
<simboss> JAI was created under bih push from JPL
<simboss> the Jet Propulsion lab fa NASA
<simboss> they used in a few mission
<simboss> and they are still using
<simboss> and it's pretty good the way it is
<mbedward> but there are some surprising gaps
<simboss> they are not interested in moving it forward
<simboss> or in babysitting
<simboss> but it's an empasse
<simboss> they do not want to spend time on it
<simboss> but they are not releasing it
<simboss> as OS
<simboss> that's why I started imageio-ext
<simboss> and I am happy to see something like JAI-operators
<mbedward> are there tricky licensing issues ?
<mbedward> for instance
<mbedward> I have written a modifed convolve operator
<mbedward> that can use an ROI
<mbedward> so it's really just a hack of the existing image op
<simboss> my advice about code from JAI is use it as a template
<simboss> but rewrite it all
<mbedward> I see
<simboss> the license is too messy to reuse that code
<simboss> for imageio
<simboss> you can reuse it, but that's another story ....
<simboss> I am hoping that sooner or later SUN will OS JAI and Imageio
<mbedward> I have a number of operators that I need for my current project
<mbedward> so I would like to open source these
<simboss> if we show them that there is a community able to ensure the continuity of the projects that might help them to make up their minds
<mbedward> that would be great
<mbedward> but surely they must know that jai is very actively used already ?
<simboss> yeh they know very well
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<simboss> but their team, while very very good, is small
<mbedward> I should compile a list of the operators that I will be needing soon
<mbedward> and send it to you
<mbedward> perhaps some are already available and I have overlooked them
<mbedward> otherwise it will be the list of things I will be coding in the next month or two
<simboss> there is one thing
<simboss> that I might want to bring up
<simboss> I did the same thing with antonello a while ago
<simboss> are your operators geospatial-aware (e.g. they need some parts of geotools torun)
<mbedward> not so far
<simboss> or do they run in the pure raster space, where there is no notion of geospatial
<simboss> I would recommed to be careful with this in order to not introduce circular dependencies between the teo projects
<mbedward> I understand
<simboss> usually I try, whenver possible, to clearly separate geostuff (geotools) from pure raster stuff (jai or imageio)
<simboss> the key for doing this is usually the gridtoworld transform
<simboss> (probably I am going to far, but I think it is important to say at least once)
<mbedward> yes, that's good point to bring up early
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<mbedward> so far
<mbedward> for example with the convolve operator I mentioned
<mbedward> that works in raster space
<mbedward> then there is a wrapper for geo-spatial part
<mbedward> but I agree with you that keeping those things separate is best
<mbedward> and I also find it easiest
<mbedward> anyway, regarding the project and site
<simboss> following you...
<mbedward> I am very open to
<mbedward> approaches to managing it / handling releases etc
<mbedward> I don't have fixed ideas or
<mbedward> requirements in that regard
<mbedward> and to begin with
<mbedward> I will just be gradually uploading my operators
<mbedward> and working on the ANTLR related strand
<mbedward> we are probably done for now - yes ?
INFO Preference "collapseMsgs" is "on".
<simboss> I think
we would like to port one operator
that is right now inside geotools
which we could probably somehow join with your stuff
we should develop also a simple operator
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<simboss> thatcan be used
to transform a single color
into a trasparent color
<mbedward> which is the operator in geotools ?
<simboss> it is buried inside the renderer since there was not complete consensu about where to put it
<CIA-21> aaime * r32368 /trunk/modules/ (4 files in 3 dirs): GEOT-2316 jdbc-ng should advertise query capabilities
<simboss> it can be used to create a piecewise transformation
<mbedward> have to go in minute - sorry
<simboss> np, I think we are done
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<mbedward> thanks simone !
<simboss> thanks to you man