[mapguide-internals] MapGuide RFC 15 - New Query Features API

[Andy Morsell]

I do like the proposed behavior change.  I think it will come in handy.
And, the user can clear their selection if they don't like the ugly blue
blobs (or we can do it programmatically for them).  I do like the idea of
this not being a forced behavior, but I do think it should become the
default as I would find it more useful than the existing behavior.  There
definitely are concerns of too many objects being displayed and selected
based on the query.  For instance, all of the parcels in Canada over $100k
in value would probably blow up the server and the resultant selection
display would be horrible.  I see that there is a maxFeatures parameter to
the methods, but the optimal value for this will change depending on the
data source.  I'm not sure the best way to handle these potential abuses,
but there needs to be some internal checking before allowing the query to
execute. 


Andy 

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Bruce
Dechant
Sent: Friday, February 02, 2007 4:37 PM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] MapGuide RFC 15 - New Query Features API

Jason,

You are correct for both situations you have described.
Perhaps this needs to be optional behavior with the new APIs only instead of
forced.

Thanks,
Bruce

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch
Sent: February 2, 2007 5:24 PM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] MapGuide RFC 15 - New Query Features API

Yes, but that means that when users select parcels at 1:10k, when they zoom
out, they will see ugly blue blobs on my beautiful map.  They might
say:  "Are they new lakes?" :-)

I'd really prefer not to have this behaviour by default.  It changes
existing behaviour for users familiar with MG 6.5, and existing MGOS/MGE
installs, requiring a certain level of end-user retraining.

What happens if they select a feature when they are zoomed out that is not
visible by default when they zoom in?  Is the detailed view obscured by the
large selection blob from a generalized feature that is not supposed to be
visible at the large scale?

Jason 

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Bruce
Dechant
Sent: Friday, February 02, 2007 16:13
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] MapGuide RFC 15 - New Query Features API

Jason,

The following assumes you are using the existing API.

The selected parcels only show up if you zoom/pan after you have already
selected them. As soon as you do a new selection at the zoomed out level
where the parcels are not visible they will not be selected. This is more
for convenience so that you can see a parcel you have selected while you
zoom to more of an overview display.

Now if you are not careful with the NEW API you could end up with lots of
features selected. :)

Thanks,
Bruce



-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch
Sent: February 2, 2007 5:06 PM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] MapGuide RFC 15 - New Query Features API

I think this is a great idea, but...

Will there be any way to disable this behaviour in the viewer?  I don't know
if I want selected parcels showing up on the map at extreme zoom levels.
Talk about ugly.

This is not a feature request.  From a cartographic standpoint I'd love to
see something like this:

Representation thresholds.  Set zoom levels where adjacent polygonal
features are merged into a single polygon, and then turn into a symbolized
point feature.  For instance, consider a Hospital:
- at 1:5000, all buildings in the hospital complex are represented, and
labelled with the word "Hospital"
- at 1:10000, these buildings are aggregated into a single rubber-band
polygon, labelled with the letter "H" in a blue circle
- at 1:15000, the hospital is represented by a letter H in a blue circle,
positioned at the center of gravity of the original features

The trick is that all just different representations of the same feature, so
selection would be maintained, and geometry operations would be applied to
the true geometry, not the simplified representation.

I'm already doing this to a certain extent manually, but it would be nice to
not have to maintain multiple copies of the same data just for display's
sake, and with this method there is no way of maintaining selection status
from one scale range to the next.

Jason 

-----Original Message-----
Subject: [mapguide-internals] MapGuide RFC 15 - New Query Features API

Hi Everyone,

We would like to submit the following RFC for open discussion and
comments:

http://www.osgeo.org/trac/mapguide/wiki/MapGuideRfc15

Please respond to the list with any feedback and we will be happy to
respond.

Thanks,   

Bruce
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