Centerline Between Polygons

[MatthewHinton1]

I am working to find planning jurisdictions for my county.  Each city within the county has a 5 mile planning radius, except one which has a 3 mile radius.  I have applied the appropriate buffers around each municipality, but I'm hoping to find a centerline between each municipality in areas where their planning jurisdictions overlap. This seems like it would be simple, but it's got me stumped at the moment.

[ChrisSnyder]

This sounds like a job for euclidean allocation (Spatial Analyst): http://resources.arcgis.com/en/help/main/10.1/index.html#//009z0000001m000000

With some monkey business, this could also be a job for Thiessen Polygons: http://resources.arcgis.com/en/help/main/10.1/index.html#//00080000001m000000

Get your city boundary allocations 1st, then do any buffering (and division of the buffer areas) as a second operation.

[Rajeshkomte]

Hello all,

guys for the last 2-3 days iam haunted with this question.. "HOW TO DERIVED CENTRELINE FROM ROAD POLYGON". i tried everything shown here but nothing happened.

[RichardFairhurst]

Hello all,

guys for the last 2-3 days iam haunted with this question.. "HOW TO DERIVED CENTRELINE FROM ROAD POLYGON". i tried everything shown here but nothing happened.

If you have an Advanced license did you try the Collapse Dual Lines to Centerline tool?  It has been a while since I tried it, so I don't recall if you have to first apply the Polygon to Line tool or not.

[Rajeshkomte]

i tried that but its not working for me... can u suggest me a different tool..?

one more thing is there any tool to generate a centreline between polygons.. i have this area polygon shpfile & i want to draw centreline between them.

Regards,

Raj

[RichardFairhurst]

i tried that but its not working for me... can u suggest me a different tool..?

one more thing is there any tool to generate a centreline between polygons.. i have this area polygon shpfile & i want to draw centreline between them.

Regards,

Raj

There is no other tool.  You have not shown a picture of what you are dealing with.  Pictures are the only way for anyone to make a better suggestion, but inevitably it will involve perhaps 20 different tools, programming, and multiple iterations.  This is an extremely complex and variant objective that no one technique will solve for every case.  Although this post about coastline extensions is a different problem, it illustrates some aspects of the complexities of trying to extend boundaries outward from polygons without overlapping existing polygons and the large numbers of tools that are potentially involved to get a desirable result.

I suggest you also show how the tool I suggested did not work for you.  If you have actual road casings it should work for the majority of the roads.

Of course real centerlines follow recorded subdivisions and improvement plans and take years to develop for a large jurisdiction, like the County I work for.  That is how we did it, but we did it as we developed the parcels, not as an after thought.  Anything else is only a hack as far as engineers and surveyors are concerned.

[RichardFairhurst]

Here is an illustration of a suggested approach for creating non-overlapping buffers.  It looks like some of the other posts in this thread have already covered this idea, at least in part (Chris' post), but the illustration shows what is possible.

This post uses tools available from ET Geowizard to create Thiessen polygons from polylines (ArcMap only does this with points.  This is most likely what you really need.  The complexity of the underlying process is obvious, since he recommends running the Thiessen polygons from lines tool overnight.

[Rajeshkomte]

sorry mates!!! was on a short break 🙂 here iam posting this pics [ATTACH=CONFIG]0[/ATTACH] i want to genrate a centreline between these polygons

[RichardFairhurst]

sorry mates!!! was on a short break 🙂 here iam posting this pics [ATTACH=CONFIG]0[/ATTACH] i want to genrate a centreline between these polygons

The attachment is not working for me.  Please post it again.

[RyanClancy]

I haven't tried this, just making it up.

1. Calculate the centroids for each of your city polygons:
    - add two fields of type 'float' to your city boundary polygon table, call them centerX and centerY
    - right click each new field and choose Calculate Geometry
    - for centerX, choose 'X Coordinate of Centroid' and for centerY choose 'Y Coordinate of Centroid'
    - finally, use the Make XY Event Layer tool to create a points layer from these centroids
    - now you have points which represent the geometric center for each of your cities

2. Use the Create Thiessen Polygons tool on your centroid points layer

The resulting polygons should have edges at the mid-points between your cities.

[Kathleen_Crombez]

Did you ever find a solution to this?

We have the same issue where the incorporated municipalities within our county have an agreement in place for future subdivision planning that divides the overlapping 1.5 mile ETJ boundaries with the median centerline. Equal distance from both sides (not necessarily equal area).

I have been banging my head on how to do this with either ArcGIS tools or SQL tools.

This is the best I have come up with so far:

1 - create 1.5 mile buffer around municipal boundary to create the ETJ boundaries.

2 - intersect the ETJ layer with itself (set output type to "INPUT" to create polygons where the ETJs overlap)

3 - use the feature vertices to points tool to create points on the boundary of the overlapping polygons.

4 - create thiessen polygons from the boundary points.

The results are looking good so far... but now I need to convert these polygons into median dissection lines.

Sure... the lines could be manually drawn in... but I am trying to automate this to account for ongoing annexations. I will post an update with my final process once I get it figured out.

In the meantime, I am interested to hear if anyone else has come up with a solid solution.

It seems this is a pretty common approach in government planning to subdivide the ETJs down the median overlap to distinguish future development jurisdiction boundaries.