Hello !
I see that I am far from being able to use all the modules available...
I am lacking a lot of knowledge of what is offered by our API.
I have also an illustration of Apache SIS usage on my personal web site
:
http://www.cinq-beaufort.com
(the application has still "build in progress" state, I hope it will
work !)
My goal is to present touristic events, celebrations, points of interest
and shows in a city, (and I would like : the way to reach it if you are not
motorized).
To work, the application queries INSEE DBF file of French cities, and
list them in an combo-box.
When the user select one, it displays a raster of the region
(metropolitan France, Guadeloupe, Martinique...) where the city belongs to
and show its outline on the map.
I've found SVG images useful to generate web display of a map.
An SVG image is created from a shapefile (or a selection of some of its
features only) by a method I managed to create with the little understanding
of mathematics, projections, I have.
The interest the SVG have is that you can apply CSS styles directly on
polygons. And this is really convenient ! For example, if you select a city
that are large enough to be seen :
Kourou (Guyane)
Arles (Metropolitan France ; small in the south)
Morne-à-l'eau (Guadeloupe, with a multipart polygon of two parts)
you will see it's shape changing colors.
However, if SVG images are good for displaying few thousands polygons,
if you attempt to send the whole oulines of all the french cities (36,500)
it will be 50 MB or more that you will attempt to send through the browser.
To avoid this, when the web application deploys, it generates some
rasters from the big shapefiles and create a PNG image for each region.
Few days ago, I had to accelerate the reading of data to make a single
feature shown more quickly when a user select a city, especially in
metropolitan France.
(the "backoffice" work done is : SELECT city_code FROM INSEE_DBF ; then
take the corresponding feature in the Shapefile and ask the web module to
display it),
and for that, being able to use Index files (.SHX of Shapefiles but also
.NDX of DBase III) will provide me direct access to the feature I really
target. I'm working on it currently.
Later, other DBF files offered by INSEE will depict me the cities
equipments, and I will have to attempt first joins queries, provided I
succeeded in managing WHERE clauses on SQL statements.
Regards,
Marc Le Bihan
-----Message d'origine-----
From: Martin Desruisseaux
Sent: Wednesday, December 02, 2015 8:45 PM
To: [email protected]
Subject: Re: An example of web application using SIS
Hello Chris
Thanks for the feedback :-)
Yes it is our intend to bring large parts of Constellation to Apache
SIS. For now we are focussing on porting Geotk, which is the engine
behind Constellation. SIS and Geotk do not have lot of GUI components
(except Swing), which make difficult to evaluate the progress. But they
contain most of the Java code (Constellation itself has more Javascript
than Java). The sis-referencing module in progress right now is one of
the largest modules and a key component of this stack.
SIS already has an "application/sis-webapp" module, which is a little
bit orphan for now. My hope is to use that module as a home for an
Apache application derived from Constellation, if peoples agree.
Before we can start porting useful parts of Constellation, the modules
that we need to complete in SIS are:
* sis-referencing (I think I'm 80% done)
* sis-coverage (for rasters)
* sis-storage (with 2 or 3 file formats)
* sis-renderer
There is much more modules to port to SIS, but once we have the above 4
we have enough stuff for building interesting GUI in SIS.
Martin
Le 02/12/15 20:02, Mattmann, Chris A (3980) a écrit :
Martin this is amazing!
Any plans on bringing the development of Constellation SDI as either
a) a new Apache project (via the Incubator), or b) into the mainline
development as an “app on top of” SIS?
It would do wonders all the work you guys have for use cases, etc.
-C
