Subject: [Thuban-list] map mode 'identify' only works when clicking on boundaries & projection management question

From: "Moritz Lennert" <[email-masked]>
Date: Mon, 7 Jul 2003 18:10:19 +0200 (CEST)

Hello,

Sorry for bombarding you with all these questions, but Thuban does look
like a possible alternative to ArcView which most of my colleagues are
using, so I really want to get to know it before showing it to others. So,
here I go:

1) When using the 'identify' mode, I have to click on the boundaries of my
polygons to select a polygon. This is not very practical, as most of the
boundaries are shared, and so I don't know which of the two polygons will
be selected. Would it be possible to create a selection where the user has
to click inside the area and not on the boundary ?

2) I don't really understand the projection management, yet ? Is it
possible to re-project data ? I've tried doing so, but I only get empty
screens. What really confuses me is that I have shpae files that (should)
use the Belgian Datum 1972, but when I load them and then click on
projection for that layer, the only one that works is <none>. All the
others giving me empty screens, including the Belgian Datum. Could you
enlighten me on how projections work in Thuban ?

Moritz

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From: Jonathan Coles <[email-masked]>
Date: 07 Jul 2003 18:51:32 +0200

> to click inside the area and not on the boundary ?

Clicking inside a polygon *is* how 'identify' should work. Do you have
this problem with the iceland sample that you could tell me how to
reproduce?

> enlighten me on how projections work in Thuban ?

When you load a layer you must select the projection that that layer's
data is in (Layer->Projection). You must then select which Projection
the map is in (Map->Projection). This can be whatever you like allowing
you to reproject the layers. If the only layer projection that is
working is <None> then perhaps the data in the shapefile is not what you
think. Is it something you could send to me so I can see what is going
on?

--jonathan

-- 
======================================================================
 Jonathan Coles                                [email-masked]
 Intevation GmbH                             http://www.intevation.de
======================================================================

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From: Bernhard Herzog <[email-masked]>
Date: 07 Jul 2003 19:30:44 +0200

Jonathan Coles <[email-masked]> writes:

> Clicking inside a polygon *is* how 'identify' should work.

If the polygons are not filled only a click on the boundary will work.
One reason it's done this way is that thuban searches through all layers
and if unfilled polygons could be selected by clicking inside of them
shapes in the layers beneath couldn't be selected with the identify tool.

There probably should be a way to tell Thuban to only select shapes in
one specific layer in which case Thuban could also allow the selection
of unfilled polygons by clicking somewhere inside of them.

Come to think of it, now that we have classifications the way Thuban
determines whether the polygons are filled is not really correct
anymore. IIRC it only looks at the default classification and thus may
assume that the polygons are not filled even when most or all of them
actually are. This ought to be fixed in some way.

   Bernhard

-- 
Intevation GmbH                                 http://intevation.de/
Sketch                                 http://sketch.sourceforge.net/
MapIt!                                           http://www.mapit.de/

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From: "Moritz Lennert" <[email-masked]>
Date: Tue, 8 Jul 2003 10:16:42 +0200 (CEST)

> this problem with the iceland sample that you could tell me how to

Bernhard's explanation was the good one. I have to fill the polygons to be
able to select them. I don't find this very intuitive, but as long as it
will be documented, I guess it's alright. I can confirm, BTW that using a
classification, I have to change the default fill color to be able to
select any of the polygons, even those filled by the classification.

> think. Is it something you could send to me so I can see what is going

I didn't select the map projection. When I do this, everything works
perfectly. Thanks !

Moritz

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From: Bernhard Reiter <[email-masked]>
Date: Mon, 14 Jul 2003 16:16:10 +0200

On Mon, Jul 07, 2003 at 06:10:19PM +0200, Moritz Lennert wrote:
> Sorry for bombarding you with all these questions, 

We appreciate your question. ;-)

> but Thuban does look
> using, so I really want to get to know it before showing it to others. 

Seriously we need a lot of feedback and help 
to make Thuban a serious alternative in the GIS field.
So keep it coming,

	Bernhard