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I have two global polygon features (layers). One is the highly detailed country shapes GADM (Global Administrative Areas) and is overlapping the less border accurate TDWG (World Geographical Scheme for Recording Plant Distributions).

I want to combine GADM with TDWG layer in the way the Identity tools does in ArcMap. I need to benefit of the highly detailed outer borders of GADM and also get the extra info with its inner borders from TWDG (like the illustration for Identity tool).

Using the tool gives satisfactory results, however it combines the attributes from both layers only when they overlap, and this can also be an issue at borders between countries where I would want that GADM borders should be considered instead of TWDG. I need to find a way to combine attributes for the remaining non-overlapping zones that share the borders with the output from Identity tool and solve the country overlapping border issue as well (see selection in image below).

The final goal is to intersect the output with points and extract the underlying data (points that fall out of GADM borders, i.e. in sea/ocean, should be excluded).

enter image description here

Below are two more print screens that catch the overlapping country borders and also the non-overlapping areas issue (it happens at the border with sea/ocean):

enter image description here

enter image description here

Perhaps another approach would be to use Spatial Join in ArcMap and intersect the points inside GADM with TWDG. Then use a search radius for points that didn't get a match.

However, I remain curious about how to solve the overlapping issues described above.

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    Instead of Identity I think you should try Union. – PolyGeo Aug 15 '17 at 7:52
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    Hi @PolyGeo. That is indeed a good idea. I tried that already and then clipped with GADM shape but doing so seems to get the similar result as Identity tool (unless I did some mistake). Actually, I tried almost everything suggested in the Overlay toolset here. Maybe there is a combination of these tools, but I feel a bit helpless at this point... – Valentin Aug 15 '17 at 8:10
  • I think you should break that very long paragraph at the beginning into paragraphs of only a few sentences for readability. While doing that try reading and re-reading your question to see what else may make it more likely to attract a potential answerer. – PolyGeo Aug 17 '17 at 9:58
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I think that the topic you need to look at is conflation.

In ArcGIS Desktop there is the Conflation toolset:

GIS data often comes from many sources. Spatial and attribute differences among various data sources sometimes requires you to resolve the inconsistencies before you can make use of the data. Conflation tools help you reconcile data from multiple sources and obtain the best possible data quality for analysis and mapping.

In particular, the tool which to be worth you investigating may be Align Features:

Identifies inconsistent portions of the input features against target features within a search distance and aligns them with the target features.

but take note of its caution that:

This tool modifies the input data. See Tools with no outputs for more information and strategies to avoid undesired data changes.

It requires an Advanced level license.

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