Larry,
I have a graph implementation which has an undershoot processor in it, have
a look at the processUndershootNodes method.
http://rsiaf.googlecode.com/svn/rs-gis-core/trunk/src/main/java/com/revolsys/gis/graph/Graph.java
The algorithm processes all nodes looking for edges within 2 units (e.g. m)
from the node which are not connected to the node. It then splits the edge
introducing a node on the line segment of the edge closest to the node.
The processCrossingEdges does the similar for overshoots (and any other
crossing segments). It does this by computing the intesection and then doing
special processing for short segments which would happen in the overshoot
case
The DataObjectGraph shows how I applied this to my DataObject framework,
although you could also apply this to the JUMP Feature framework.
Paul
P.S. All code is under the Apache 2.0 license copyright Revolution Systems
Inc.
On Thu, Jun 12, 2008 at 10:53 AM, Larry Becker <[EMAIL PROTECTED]>
wrote:
> Does anyone have a link to a web page that talks about the requirements of
> undershoot, overshoot, etc.? I'm wondering if you have, for instance, three
> lines ending at (within tolerance ) the same point, how do you decide which
> point to snap the ends to? Pick one end randomly, average their positions,
> or what? Should there be options for one layer to be considered the master,
> and all others (or editable layers only?) snap to it?
>
> Larry
>
> On Thu, Jun 12, 2008 at 12:00 PM, Nacho Uve <[EMAIL PROTECTED]> wrote:
>
>> I'm very interested about that. I was working on a plugin to repair
>> connectivity errors (undershoot, overshoot, nodemismatch, etc...) but I
>> haven't got time to continue with this issue... maybe in the future I will
>> take again that project. If any person wants work on that please I would
>> like collaborate... I have some ideas to do it.
>>
>> However, I know that Kosmo has a couple of tools (CAD Tools) to extend and
>> to shorten lines.
>>
>> Best regards,
>> Nacho
>>
>>
>> 2008/6/12 Martin Davis <[EMAIL PROTECTED]>:
>>
>> JUMP doesn't. JCS I don't think did either. That's just because it
>>> wasn't a requirement for conflation per se - it's more of a data
>>> cleaning thing.
>>>
>>> Clearly this would be nice to have... all someone has to do is to write
>>> it.. 8^)
>>>
>>> Stefan Steiniger wrote:
>>> > That is a good question I asked yesterday myself when writing the
>>> > (other) person an answer on the user list.
>>> >
>>> > @Martin: can you give a comment? Does Jump have tools to remove
>>> > overshoots and undershoots?
>>> >
>>> > Larry Becker schrieb:
>>> >> Fixing undershoots and overshoots for lines seems like one of the
>>> >> most common and relatively easy to implement features that a GIS
>>> >> should have. Can it be that we have overlooked this, or is it a JCS
>>> >> feature that hasn't been ported over yet?
>>> >>
>>> >> Larry
>>> >>
>>> >> On Thu, Jun 12, 2008 at 9:52 AM, Sunburned Surveyor
>>> >> <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>>
>>> >> wrote:
>>> >>
>>> >> ---------- Forwarded message ----------
>>> >> From: Assessor <[EMAIL PROTECTED]
>>> >> <mailto:[EMAIL PROTECTED]>>
>>> >> Date: Thu, Jun 12, 2008 at 5:24 AM
>>> >> Subject: OpenJUMP question
>>> >> To: [EMAIL PROTECTED]
>>> >> <mailto:[EMAIL PROTECTED]>
>>> >>
>>> >>
>>> >> Sir:
>>> >>
>>> >>
>>> >>
>>> >> I am neither a computer nor GIS expert, although I eventually can
>>> >> figure out how to solve problems with computers; sometimes the
>>> long
>>> >> way around.
>>> >>
>>> >>
>>> >>
>>> >> PROBLEM: We draw all our maps in AUTOCAD. We have a fairly good
>>> >> "street map" which is based on our "tax map". The Tax map is
>>> >> really a
>>> >> collection of about 125 sheets comprising 10,000 parcels, varying
>>> >> scales, etc.
>>> >>
>>> >>
>>> >>
>>> >> We edge matched them and produced the street map as one layer but
>>> >> don't know how (or AUTOCAD won't let us) export it as a polygon
>>> >> shapefile. As it stands now, it comes out as a "line"
>>> >> shapefile. The
>>> >> last edition of the map was sent to a consultant who converted it
>>> >> to a
>>> >> "polygon" shapefile, probably using an ESRI product. That costs
>>> >> money
>>> >> that we don't have, and we want to do it a couple times per
>>> >> year. We
>>> >> use the Map with a database that is used for almost everything
>>> >> that I
>>> >> do as well as many other departments also.
>>> >>
>>> >>
>>> >>
>>> >> Once we get the base layer (polygons) we can do all kinds of GIS
>>> >> stuff
>>> >> with it, but we don't have a way to solve the only apparent
>>> problem
>>> >> that I think we have; namely: fixing overshoots and undershoots.
>>> >>
>>> >>
>>> >>
>>> >> No matter how good our line work is in AUTOCAD, when it comes out
>>> >> as a
>>> >> line shapefile, there are thousands (like about 18,000) over or
>>> >> undershoots. I have figured out how to fix the overshoots in
>>> >> OpenJUMP
>>> >> by using the "nodeline" tool, but I don't see how to fix
>>> >> undershoots.
>>> >> The "polygonize" tool works great, but it needs "closed
>>> >> polygons." If
>>> >> I could fix the undershoots, even by making them into overshoots,
>>> >> I'd
>>> >> be fine. I know ARC has "clean" and "Nodesnap" and tools that
>>> make
>>> >> what I want to do easy. The question is: can this be done with
>>> >> OpenJUMP or one of its plugins? If so, can you advise? I have
>>> been
>>> >> digging around on the web for days!
>>> >>
>>> >>
>>> >>
>>> >> Sorry for the long email, but I figured more info is better than
>>> >> less.
>>> >>
>>> >>
>>> >>
>>> >> Thanks.
>>> >>
>>> >>
>>> >>
>>> >> Township of Voorhees
>>> >>
>>> >>
>>> >>
>>> >>
>>> >>
>>> >> Michael C. Kane - Municipal Assessor
>>> >>
>>> >> [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
>>> >>
>>> >> www.voorhees-nj.com <http://www.voorhees-nj.com>
>>> >>
>>> >> 620 Haddonfield-Berlin Rd.
>>> >>
>>> >> Voorhees, NJ 08043
>>> >>
>>> >>
>>> >>
>>> >> 856-429-7767 (V)
>>> >>
>>> >> 856-429-5756 (F)
>>> >>
>>> >>
>>> >>
>>> ****************************************************************************************************************************************************************
>>> >>
>>> >> CONFIDENTIAL AND PROPRIETARY:
>>> >> This email message is intended only for the use of the individual
>>> or
>>> >> entity to which it is addressed and may contain information that
>>> is
>>> >> privileged and confidential; nor is it, unless specifically
>>> stated,
>>> >> intended to be relied upon by any person or persons other than the
>>> >> individual or entity named above and no warranties or
>>> >> representations
>>> >> are made or intended to persons or entities not named above. If
>>> the
>>> >> reader is not the intended recipient, you are hereby notified
>>> >> that any
>>> >> dissemination, distribution or copying of this communication is
>>> >> strictly prohibited. If you have received this communication in
>>> >> error, please notify us immediately by telephone, return this
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>>> >> to [EMAIL PROTECTED] and delete all copies. Thank you.
>>> >>
>>>
>>> --
>>> Martin Davis
>>> Senior Technical Architect
>>> Refractions Research, Inc.
>>> (250) 383-3022
>>>
>>>
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>>
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