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I'm working on a map design that integrates many (around 300 separate map layers) datasets that need to be made available to users within the same map (just for viewing). I've looked at creating a table of contents with high level and sub categories but it just seems very clunky.

We are harvesting the datasets as web map services. The WMS URLs are stored in an oracle database where they are configured into 9 main categories to provide a top level summary table of contents. We also have an advanced table of contents (also configured in Oracle) which arranges the dataset layers within the main category list. The whole thing is becoming unmanageable and not at all user friendly but we still need to make all the datasets available.

Does anyone have any good guidelines/best practice/inspirational ways of dealing with large sets of data on a map?

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What software are you using? Are the maps just for viewing or do your users edit the maps in anyway (I think of a map as a finished product as opposed to a GIS environment). –  MappaGnosis Feb 25 '14 at 11:34
    
Yes, the maps are just for viewing. We are harvesting the datasets as web map services. The wms urls are stored in an oracle database where they are configured into 9 main categories to provide a top level summary table of contents. We also have an advanced table of contents (also configured in Oracle) which arranges the dataset layers within the main category list. The whole thing is becoming unmanageable and not at all user friendly but we still need to make all the datasets avaiable. Any help is much appreciated. –  user2932466 Feb 25 '14 at 11:57
    
Would you be able to use the edit button beneath your Question to revise it with additional details like these that come out in response to Comments, please? –  PolyGeo Feb 25 '14 at 12:10
    
I think this is almost impossible without a table of contents. Do you want to avoid it mainly because it looked clunky at first or are there other reasons? –  BritishSteel Feb 3 at 15:49
    
@user2932466 If my answer is useful for you, please upvote it. If it solves (or helps you solve) your problem, please mark it as accepted. That's how you reward answerers in GIS.SE. –  gcarrillo Feb 10 at 1:50

2 Answers 2

Your problem is trying to present everything on one map - so make a number of themed maps. Since you are using WMS and the maps are just for viewing, I would be tempted to create a web-based interface and have layers in pre-defined logical groups across a series of maps (instead of a single map with hundreds of layers). A user would then select the map (and therefore the selection of layers available).

You could simplify some of this by using Geoserver to interface with your Oracle backend and make use of Geoserver's ability to reference layer-groups. So each layer-group represents selections of layers that logically go together.

You could then refine the interface to allow the users to select additional layers to add/remove to the map - thus giving them the flexibility to roll their own map. You could do this my drop down lists on the web-page with additional layers in logical groups.

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I recommend you reading Paralysis of Choice by Brian Timoney for a nice introduction to the cognitive problem a large ToC entails. He demonstrates with numbers that single topic maps are more frequently visited that all-purpose maps.

Timoney has named this usability problem as Layerrhea. He concludes:

Cures for Layerrhea: a) break out most important layers into single-topic maps; b) provide data downloads for power-users; c) roll your own basemap with supporting, contextual layers baked-in.

As he mentions, you could think about creating meaningful base maps that would group layers by topic, so users would only have to choose among 9 base maps and not among ~300 layers.

On the other hand, if you have to deal with ToCs, I would suggest you to implement basic search functionality at the top of your ToC, in a way that it allows users to filter the ToC layers (like in this application). This way, you can show them only the layers that match a specific search term (see figure below).

enter image description here

The search box could be the entry point to the information users have at their disposal, so I would make it prominent in the web page.

You could also think of using a select list widget (comboBox) to make your users select the topic before any meaningful map interaction, like in the Mecklenburg Geoportal, which doesn't use a (conventional) layer ToC.

enter image description here

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