Combining shapefiles for land classification by consensus?

[tt1]

Manual classification of satellite imagery can be difficult due to the complex and often non-distinct boundaries between different types of landscapes. As a result, the manual delineation of boundaries can vary between annotators 

Therefore, I have asked a number of volunteers to map a single satellite image of the coast using polygons. I wish to combine all of their shapefiles to determine the final polygons for each class.

There are three classes (sand.shp, water.shp and vegetation.shp).  

Due to human error, individual annotators will often have "gaps" where the boundaries of two polygons have not snapped or "overlaps" where two different polygons (e.g., "sand" and "water") will overlap. 

What I would like to do is combine all of their shapefiles into a final map, whereby if the majority of volunteers shapefile's agree for a given region, that region will be classed. If there is a disagreement between volunteers, then the region is labelled as "non-classified". 

What is the best process of doing this? 

I imagine I could convert the shapefiles to raster and do a raster calculation to class each pixel by a threshold, where if >70% of users agree on a class it is that class. If not, then class as "non-class". However, I would like to know if it's possible to do this by another, and perhaps more simpler, means by directly working with shapefiles and utilising ArcGIS Pro /ArcMap tools? 

[DanPatterson_Retired]

Count Overlapping Features—Help | Documentation 

is one interesting possibility.. 

But more generally, you should look at the Overlay tools

An overview of the Overlay toolset—Help | Documentation 

Conversion to raster and there overlay equivalents are also the other option

[tt1]

Hi Dan

Thanks for this. 

I've been playing around with the "count overlapping features" tool but have run into an issue. 

It seems the tool will only class a region as "overlapping" is if the two polygons share similar extents, rather than if they are overlapping the same space. 

For example, let's say I have two manually labelled maps of a region of vegetation. 

One map represents the region using a single large polygon. 
The other map represents the region using lots of small polygons. 

I try to use the "count overlapping features tool" to create a "master map". However, the tool fails to count the overlap. 

The tool will only count overlapping features if they both maps use a large single polygon or both use many small polygons. 

I wish to use ArcGIS to map polygons that overlap in a region - regardless of the polygon's individual size.  

Below is mock example of my issue, where the only region classed as "overlapping" is a area where two polygons of similar extents and class exist.

In reality, the majority of map should be classed as overlapping. Only the boundaries of the objects being labelled should be classed as "not overlapping", where different users define different boundaries.