Introduction to Custom Map Layers
Custom Map Layers are used for adding map data to your account that cannot be represented by the built in layers options. Once added, the custom layer will be available to turn on/off from any map. This means that these layers are often for representing non property-specific layers, since most map data related to individual properties can find a home in either a work item layer or the 'record specific' layer.
For example, custom map layers can be used to see:
Watershed Boundaries
Entire Town, County, or State Parcel Boundaries
Abutting Open Space Boundaries
Recent Satellite Imagery
Custom Map Layers are accessible via Settings > Map Layers > Custom Map Layers (must be an administrator to access settings).
There are two types of custom layer: Imported layers and linked/service layers. They have very different uses and applications.
Importing a Custom Layer
Imported custom layers are uploaded to your Landscape account. They are also downloaded by Landscape Mobile for viewing in the field. This means that the custom layer field is not appropriate for large layers like town/county/state parcels. If you try to import too large a layer, it will impact the performance of your maps and could cause the app to crash.
Common examples of imported layers include watershed boundaries, ecological zones, and internal project areas.
The neat thing about imported layers is that they can be made searchable. This means that, for example, if you import your regional watershed boundaries into Landscape and make them searchable, you can use Data Viewer to see which properties are in which watersheds. Note that, if you're interested in using this feature, Landscape can only index by a single attribute field which needs to be called 'NAME'.
You can only import vector data as a custom layer. You cannot import raster data.
Here's a video on importing and querying on a custom layer:
Linked/Service Layers
In addition to uploading data to Landscape, you also have the ability to link to third party service layers. Landscape allows you to link to an ArcGIS Map Service, XYZ Tile Service, or WMS Tile Service. This means that the data is not stored on your account, but is instead linked to another location, much like linking to a third party storage platform like Dropbox or Google Drive and storing your documents there. Service layers are not available to Landscape Mobile.
Currently Landscape does not support any authentication requirements between your account and the layer you're linking to. This means that if the service is behind any sort of paywall, Landscape will not be able to access it.
However, there are many freely available service layers which can be linked to. For example, the State of Massachusetts maintains a statewide parcel dataset, as well as publicly available satellite imagery.
Here's a video on how to find and link to one of these layers using ArcGIS Online:
Disclaimer: always check the license info for spatial data hosted online. Landscape provides the ability to display and copy data from hosted spatial data sources, but you are responsible for compiling with the license terms.