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I have a network data set for footpaths which I have generated through the collation of path networks from a variety of sources.

I want to compare this with another dataset which also contains a path network, to see which is more complete / where there might be features in one dataset and not the other.

It is likely that the features representing the same path will be non-identical between the datasets, but they will be within a couple of metres of each other.

How could I go about this?

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What GIS software do you have access to? –  Mapperz Apr 21 '11 at 13:47
    
ArcInfo with extensions, QGIS... It is more the method I am struggling with than specifics, but specifics will of course also be useful. –  gisuser Apr 21 '11 at 14:17
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This is a conflation problem and essentially a duplicate of gis.stackexchange.com/questions/8262/…. See the comment about OpenJump and RoadMatcher. –  Sean Apr 21 '11 at 15:49

3 Answers 3

Without using specifics, you will need to create an spatial relation between the two datasets. One method to do this is to create a buffer around the features of dataset1 of a set tolerance and compare the output with dataset2. Relations you should look for are:

  1. Dataset2 within Dataset1 - this will give you features that are very similar or follow the same path
  2. Dataset2 intersects Dataset1 - this will give you those features that deviates from the path or is possibly new
  3. Dataset2 not intersects Dataset1 - this will give you those features that are completely new.

The buffer can be used to manage tolerance to deviation between two datasets. A larger defined buffer will be more forgiving of larger path deviations.

An alternative is to use a similar method using the path endpoints of both datasets, where you create a buffer of dataset1 and if your spatial 'within' relation identifies those paths that are similar. Those endpoints that are not with in tolerance could be considered new paths.

Hope this give you some ideas.

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+1 Buffering is a creative and flexible option for this and many other tricky comparisons. It works with many GISes. –  whuber Apr 21 '11 at 18:36

Okay since you have 'ArcGIS ArcInfo with extensions' you can use the

Compare Layer to Snapshot (Production Mapping)

This tool accepts points, polylines, polygons, and annotation feature layers as input

[geometry, extent, or symbology]

http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//010900000016000000.htm

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Is "Compare Layer to Snapshot" the newer version of "Feature Compare"? –  artwork21 Apr 21 '11 at 15:53
    
is better as you can compare annotation and symbology [Cartographic Extension called 'Production Mapping' required –  Mapperz Apr 21 '11 at 15:54

In ArcGIS 9.3.1 there is a tool called Feature Compare within the ArcToolbox, that will compare various aspects between two features (Maybe 10 has the same tool). You could also run the Erase tool to identify where discrepancies exist between your two networks.

ArcGIS 9.3.1 http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?id=1720&pid=1719&topicname=Feature_Compare_%28Data_Management%29

ArcGIS 10 http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//001700000004000000.htm

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