# Geometry :

Subject: [ggl] Snapping
From: Barend Gehrels (Barend.Gehrels)
Date: 2009-11-27 03:43:45

Hi Stephen,

OK, I'm curious. I didn't understand your diagram completely. You
mentioned that another would come, one so didn't react on this earlier.
I understand that you've two lines, and basically want to snap one line
on another line, based on mutal vertex distances. Do you also snap
between vertices? According to your diagram, yes.
Do you also need to snap one line to multiple lines? Or more lines to
multiple lines?

Regards, Barend

Stephen Leary wrote:
> Thanks Barend,
>
> I will do some simple snap tests at the weekend.
>
> Stephen
>
> On Sun, Nov 22, 2009 at 10:29 PM, Stephen Leary <sleary_at_[hidden]
> <mailto:sleary_at_[hidden]>> wrote:
>
> This is a very crude first attempt at a diagram (I will do another
> soon) but the left hand scenario the line at an angle snaps to the
> other side with the result being on the right.
>
> In GIS we usually have rules for what snaps to what. Most common
> new features snap to existing ones.
>
> If we get this snapping in place it would allow us to do ISO 19107
> topology further down the line.
>
> Cheers,
> Stephen
>
> On Sun, Nov 22, 2009 at 6:48 PM, Barend Gehrels
> <Barend.Gehrels_at_[hidden] <mailto:Barend.Gehrels_at_[hidden]>> wrote:
>
> Hi Stephen,
>
>
>
>> You mean something like: ggl::snap(geometry_from,
>> geometry_to, snapped_geometry);
>>
>>
>> Something like that yeah. Most of the actual work involved is
>> in finding points on a line that are at the snapping
>> tolerance distance from "snap to" feature.
>
> Ah, of course, specifying a tolerance is essential :-)
>
>
>
>>
>> I'll have a look at the extension model then and see how this
>> can fit. For me a snap feature is just as important as a
>> "buffer" feature.
>
> OK, you'll need the account then, I'll send it to you privately.
>
>
>>
>> poly/poly breaks down to multiple line/line snaps. line line
>> is a complicated beast because all parts of the line that are
>> within a snap tolerance of the "snap to" line get snapped.
>> I'll produce some diagrams of this and post them.
> I see. Points/lines might be snapped potentially to multiple
> lines or holes. I'll wait your diagrams.
>
> Regards, Barend
>
>
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> ggl_at_[hidden] <mailto:ggl_at_[hidden]>

>
>
>
>
> --
> Stephen Leary
>
>
>
>
> --
> Stephen Leary
> ------------------------------------------------------------------------
>
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>

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