[ka-Map-users] Drawing polygon in ka-map

[Lorenzo Becchi]

Hi Stephen,
I've lost this e-mail because was not in the list, sorry.
I'm answering you publicly to share this thinking, hope it's ok for you.

your questions:
> Would it be possible to get you to bubble polygon creation/editing  
> up to the top of your stack :) Or more generally, geometry, instead  
> of just polygons. It would be nice if this feature would allow the  
> user to:
>
> create:
> select locations using the mouse on the map and
> "save" the polygon back to the server in map coordinates (ie: lat/ 
> lon).
>
> edit:
> get a polygon from the server via unique id or unique id via a query
> optionally request the polygon be locked
> allow vertices to be added, deleted, moved
> "save" the polygon back to the server or
> "save as new" the polygon back to the server
> bonus points: suport some special case polygones:
> 1) square or rectangle, optionally rotated about a corner
> 2) circle and N-side polygon, based on center, radius or radius point
>
> unlock:
> release a lock before it times out if requested above.
>
> delete:
> request a polygon on the server be deleted via unique id or query



This ideas are in my and Andrea's mind since quite a long time. I  
know we are not the only ones.
We scanned all technologies to see how to do this and to do it  
strong, mostly universal.
Vectorial drawings are the system to use.
The system PG has developed is a good starting point to do this but  
there are some doubts:
1) browser support for vectorial graphics is not fully stable and not  
universal (not standard). PG had to play with different technologies  
to manage his API for ka-map.
2) in this situation only "little" polygons or lines can be managed.  
"little" is a relative concept and in this case it starts to be more  
relative. Maybe it's OK to desing a 20 vertices polygon but what  
about a country border? how can you offer a system that works just  
with 20-100-1000 vertices and not for 10.000?
this in not depending from your skills but from browser support and  
development.
more over there are other problems related moving 10.000 point over  
the internet.
3) I've seen something nice done with flash that has a good vectorial  
management system. The problem? flash is proprietary, that's enough  
for me. more other you need a plug-in to use it in your browser and  
connection problems are the same of any other technology.

So, my sentence is: browsers are not yet mature to do this.
(or maybe, I'm not yet mature to do this)

Now I have to say that I'm always looking for a way to mind this gap.  
Once I'll be ready I'll surely let you know.
:-)

anyway there are many experimental ideas we are working on.
One dream is to create a Web Interface for some/many GRASS functions  
using ka-Map framework.

hope my answer doesn't look so simplistic.
thanks for asking and commenting
ciao
Lorenzo




On 08/ago/06, at 14:50, Stephen Woodbridge wrote:

> Lorenzo Becchi wrote:
>> Elene, we are working on it.
>> We'll be please if you'll help us testing  and debugging it.
>> Please be patient a while more...
>> you can trace CVS updates with:
>> http://cia.navi.cx/stats/project/ka-map
>> anyway, main changes will be commented on the list.
>
> Hi Lorenzo,
>
> I know you have been busy contributing LOTS of great stuff to ka- 
> map. I particularly like kaExplorer. Thanks. I took a vacation in  
> the Dominican Republic a few years ago. It is a great place to  
> visit, I hope you are enjoying the sun and the culture.
>
> Would it be possible to get you to bubble polygon creation/editing  
> up to the top of your stack :) Or more generally, geometry, instead  
> of just polygons. It would be nice if this feature would allow the  
> user to:
>
> create:
> select locations using the mouse on the map and
> "save" the polygon back to the server in map coordinates (ie: lat/ 
> lon).
>
> edit:
> get a polygon from the server via unique id or unique id via a query
> optionally request the polygon be locked
> allow vertices to be added, deleted, moved
> "save" the polygon back to the server or
> "save as new" the polygon back to the server
> bonus points: suport some special case polygones:
> 1) square or rectangle, optionally rotated about a corner
> 2) circle and N-side polygon, based on center, radius or radius point
>
> unlock:
> release a lock before it times out if requested above.
>
> delete:
> request a polygon on the server be deleted via unique id or query
>
> It would be up to the user of the functionality to write the  
> polygon.php or geometry.php script to implement the backend. But I  
> would be happy to write a simple reference server-side script to  
> support this functionality and say store and retrieve the data from  
> postgis. By using postgis, it would be simple to include the data  
> in the database as a layer in the mapfile for display and query.
>
> Please let me know if you are interested. I would be happy to work  
> up a spec for the server scripts and work with you to define the  
> data exchange for the ajax requests. I know this is relatively  
> small effort, but it is something that I can do to support this  
> effort.
>
> Best regards,
>   -Stephen Woodbridge

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