Web based digitizing

Hi,

I was looking different implementations for web based digitizing and
really came out with nothing. Most common "digitizing" implementation is
selecting one hotspot and attaching some attributes to it but I was
looking for more complex solution that would involve annotations with
text, lines, areas, arcs/circles/curves, placing symbology etc. and
editing them.

I know that one could use divs, SVG, canvas, java applet, flash/flex at
least.

I've implemented very basic digitizing with divs and applet methods but
does anyone know demo or complete site that uses SVG or flash/flex to
produce mapping with digitizing?

--

Jani Tiainen

wrote:



Have you looked at MapBuilder (http://communitymapbuilder.org/ )? I
think the entirely client-side approach you are looking at is probably
not the way to go; SVG, Flash etc. don't know about "real world"
coordinate systems, so you really need something backed by a Web
Feature Server or similar; WFS-T is designed to do what you want, but
there aren't many clients for it out there.

Paul

Paul Cooper kirjoitti:

I'm now just looking for implementations about _digitizing_ with
browser. Spatial data viewers exists for almost any flavor I need:
images, svg, flash, java-applet etc. That's not problem. But problem is
that there is very few implementations where you can construct spatial
objects through browser.

I have done simple java-applet and div-based html creation/editing for
spatial objects (points, lines, polygons, circles), but I'm looking for
more complex solution - or knowledge that those even don't exists (for
reason?).

WFS-T is just one standard to transfer data to (and from) server. Not
too many libraries or server with that transaction capabilities. Plain
WFS implementations you can find a lot. And it doesn't solve my problem:

How you can create/modify (draw) spatial objects in browser? Preferably
in vector format.

--

Jani Tiainen

wrote:



The point about MapBuilder and WFS-T is that they allow remote
modification of data. If you really want to modify or create spatial
objects in the browser, then this is the starting point you need to
work from. As I noted before, the BIG problem is that your browser is
unaware of the complexities of spatial reference systems, and without
that you don't have a working system.

You must also have interaction with a server; otherwise how are you
going to store your data? The security model of browsers doesn't
normally allow modification of local files.

Paul

Paul Cooper kirjoitti:

Yes they do, but now I'm not interested in servers. I'm just interested
in clients. And that is big problem but not for reasons you mentioned.


I'm obviously not making myself clear here. :)

At this point I'm not interested in technology/protocols etc. about data
transfer between browser (client) and server. WFS-T is still just one
open (standard) protocol to do it.

All I'm looking for is a tool that can show raster/vector map and you
can draw points, lines (polygons) and circles on top of it and post it
back to _any_ server that implements _any kind of saving method_

Most of implementations I've seen this far can only handle points. You
can set POI on map and maybe even save it (to datastorage). All of those
seem to use some kind of proprietary protocol. That's just what
MapBuilder samples seem to do. you can make POI. But where you can draw
areas for example?

I've myself implemented applet that can be used to digitize and save
geometries to datastorage - it doesn't use WFS-T nor mapserver but my
proprietary server and protocol. It's just very clumsy to use and needs
java to be installed on end user machine.

I've seen div (dhtml) based digitizing with AJAX. It uses also
proprietary server and protocol. Problem is slowness - creating lines
using divs is more than slow.

I've studied possibility to use SVG DOM object to handle vector data
(from server or drawn) but I haven't found any implementations that
would do such things.

Also I'm looking for possible implementations using digitizing with
flash/flex technology.

For decades we have had desktop clients for creating and modfuing GIS
data, but I'm really looking ways to do it on web, currently this seems
very good oppurtunity for OSS project since not many exists.

--

Jani Tiainen