Thanks Andy- I appreciate the info. Something to consider in the future.
Maybe the dev team should take a look at it as they investigate replacing JAI?
Looking forward to some examples/docs whenever you get to it.
Take Care,Peter
From: Andy Turner <a.g.d.tur...@leeds.ac.uk>
To: Jody Garnett <jody.garn...@gmail.com>; teeschke <daniel.te...@web.de>;
Peter Borissow <peter.boris...@yahoo.com>
Cc: GeoTools Users <geotools-gt2-users@lists.sourceforge.net>
Sent: Thursday, December 3, 2015 10:18 AM
Subject: Re: Grids
#yiv1662499447 #yiv1662499447 -- P
{margin-top:0;margin-bottom:0;}#yiv1662499447 Yes, no_data values can be set.
In calculations, no_data values are treated as I have thought was appropriate,
for example in generalisations that calculate averages etc. You can request the
value of the Grid at a point and there are utility type methods that get all
values within a set distance in coordinate space.
The input data does not need to be tiled. I load input data into Grids using an
ESRI ASCII grid format. Typically this tiles the data the number of rows and
the number of columns in each tile (chunk) can be set and don't have to be the
same.
You can do everything in Grids without JAI, so it is not really required, but
more of an optional for storage of data in chunks. However, not all the Grids
source will compile without it. I did want to separate this out completely and
have the JAI data store as a sort of plugin, but have not got around to this -
and from the sounds of it, it might be best to factor JAI out completely anyway.
Grids depends on my Generic library (https://github.com/agdturner/generic)
which helps handle the swapping of data (amongst other things, in particular
calculations using BigDecimal arithmetic). The Generic library itself depends
on Apache Commons Math. Again, that is not much of a dependency and could be
factored out.
I don't have a lot of time right now, but I'll work on some examples and reply
in due course.
Cheers,
Andy
From: Peter Borissow <peter.boris...@yahoo.com>
Sent: 03 December 2015 14:50
To: Andy Turner; Jody Garnett; teeschke
Cc: GeoTools Users
Subject: Re: Grids Hi Andy- Sounds interesting. Does the Grids library
support no_data and random access to a region of interest? Does the input
raster need to be tiled? Is JAI required? Any other dependencies? Any known
limitations?
Also, it would be interesting to have a couple simple examples on your github
page for how to load in a raster and access pixel values at a given point on
the image.
Thanks,
Peter
From: Andy Turner <a.g.d.tur...@leeds.ac.uk>
To: Jody Garnett <jody.garn...@gmail.com>; teeschke <daniel.te...@web.de>
Cc: GeoTools Users <geotools-gt2-users@lists.sourceforge.net>
Sent: Sunday, November 29, 2015 2:55 PM
Subject: Re: [Geotools-gt2-users] embedding GeoTools is always a pain
One thing I think it is worth pointing out about Grids (as it is fairly
fundamental) is that the underlying coordinate system is based on BigDecimal.
The calculations for where a grid value is located are based on BigDecimal
arithmetic. This is because otherwise there can be problems when dealing with
rasters with very large numbers of rows and columns. Although Grids will handle
multiple rasters with very large numbers of rows and columns, there are non
memory/disk resource restrictions on how many rows and columns any grid can
have and this will vary depending on how the definition of the chunks (data
model used to store these).
I have not parallelised anything much in grids, but many grid operations can be
parallelised and I have thought about this in respect of memory handling.
Some of the memory handling catches OutOfMemoryErrors to deal with problems if
they do come up. It is much better though to test available memory to judge if
the grids processing component is running low. In the Generic library upon
which Grids depends there are useful functions for this.
From: Andy Turner <a.g.d.tur...@leeds.ac.uk>
Sent: 29 November 2015 19:27
To: Jody Garnett; teeschke
Cc: GeoTools Users
Subject: Re: [Geotools-gt2-users] embedding GeoTools is always a pain Hi Jody,
Hi everyone,
Many moons ago I started developing a raster data calculator based on the
Raster class of GeoTools. I developed this so that it tiles/chunks 2D square
celled rasters into chunks of the same size, but configurable rows and columns.
I called the library Grids. Every Grid in Grids currently either holds ints or
doubles, but I had envisaged developing ones for boolean and BigDecimal too.
Every Grid shares a Grids_Environment object for memory handling, so if when
processing the system runs low on memory, various data/tiles/chunks can be
swapped to file space. There can be quite a lot involved in being clever about
swapping data to and from different memory stores. Anyway, the library can
handle multiple large grids on modest resources for many operations. Perhaps
this can be evolved to be the JAI replacement.
In Grids there are various ways of storing chunks. They can be stored as
HashMaps or Arrays or in other ways depending on their size. At present these
can be stored as JAI images too, so currently there is a dependency on JAI for
these, but it is not necessary at all.
Here is a link to the latest Grids on GitHub:https://github.com/agdturner/grids
| | agdturner/gridsgrids - A Java spatial raster data handling library.Read
more... |
There is a bit more history of grids
here:http://www.geog.leeds.ac.uk/people/a.turner/src/andyt/java/grids/
Any questions I'll be happy to try to answer them and provide examples etc.
Cheers,
Andy
From: Jody Garnett <jody.garn...@gmail.com>
Sent: 29 November 2015 18:40
To: teeschke
Cc: GeoTools Users
Subject: Re: [Geotools-gt2-users] embedding GeoTools is always a pain We are
starting to look at replacing JAI, and will be doing design and fundraising
over the course of 2016. JAI is not open source so we are unable to place it on
maven central. The second part is service provider interface is a pain in some
environments, and the "service registry" we use looks to be unsupported in Java
9.
| | Replace JAI · geotools/geotools Wiki · GitHubgeotools - Official GeoTools
repository ... You can clone with HTTPSRead more... |
If you have any suggestions on parties interested in the above tasks we would
love to know.
--Jody Garnett
On 24 November 2015 at 14:35, teeschke <daniel.te...@web.de> wrote:
Dear GeoTools users and developers,
after embedding GeoTools in my n-th project I am very annoyed about the
complexity and pitfalls of this process. Two Scenarios to describe the
problem:
First: I wanted to parse a KML file and try to follow the Geometry Guide on
http://docs.geotools.org/stable/userguide/library/xml/geometry.html#kml-parser
1. add boundless repository and include gt-api, gt-main and gt-epsg-hsql
because I learned my lessons from projects before
2. trying to resolve the KMLConfiguration
a) adding gt-xml and gt-geometry modules as dependencies which is not
documented but seems to be meaningful because the how-to is about this
b) adding the xsd/gt-xsd-kml module as dependencies because I stumbled into
the xsd folder and it sounds meaningful as well
--> lucky me: it was the right one
Sidenote: I needed to scroll through the boundless repository manually to
scan for this modules
Second Scenario: whenever I want to do something with grid files - the JAI
library is required but not hosted in the maven central or boundless repo.
So I must use another repository (osgeo/webda) which seems to be the last
one which is hosting the JAI library :)
At the end of the day all this searching and trying needs a lot of time, is
not a pleasure and from my point of view not state-of-the-art because all
other libraries are available at maven central and are able to manage their
own dependencies. But in case of GeoTools I always need to look into
reference projects to find out how I was getting it the last time.
What are your experience with scenarios like this? Are you adding all
modules into the pom to not run into problems I always got or is there a
how-to I missed? :)
Thanks and kind regards,
Tee
--
View this message in context:
http://osgeo-org.1560.x6.nabble.com/embedding-GeoTools-is-always-a-pain-tp5238366.html
Sent from the geotools-gt2-users mailing list archive at Nabble.com.
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