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Problem: Duplicate labels are present for tiled or cached map services in ArcGIS Online

Description

When creating a tiled map service, the label properties in a map document are set to place one label per feature. However, there are multiple labels on a single feature after the tiled map service is published in ArcGIS Online.

In other instances, duplicate labels are present for map services created using the Maplex Label Engine in ArcMap. When map services are cached, duplicate labels appear in ArcGIS Online.

Cause

This is a known limitation with tile caches.

During a caching job, ArcGIS draws large areas to help reduce duplicate labels. These large areas, known as 'supertiles', are then divided into a smaller, individual tiles. Each tile is generated independent of the next tile. Duplicates can occur at the super-tile boundaries. This is because when a supertile is labeled, the label placement engine is not aware of labels on adjacent supertiles. The labeling engine may be making an effort to include as many labels as possible within a supertile, thereby placing some labels near the edge. It may do the same thing on the adjacent supertile, causing duplicates near the supertile boundaries. Therefore, there may be duplicates when viewing more than one supertile.

Duplicate labels are present in cache tiles if a dynamic labeling engine is used in a map document to place labels. However, these do not occur any more frequently than 4,096 pixels in any direction.

Solution or Workaround

Option A: Create an annotation layer to replace the dynamic labeling engine

1. Create an annotation layer in the map document. This ties the labels to a single point rather than drawing the labels dynamically in each view of the map services. Please refer to the following page, creating annotation layers for map caches, for more details.

Note:
An annotation is a special layer in which each label is treated as a feature with attributes. The attributes include an assigned place on the map for each label. An annotation layer can be edited to remove duplicate labels.


2. Publish the annotation layer alone to ArcGIS Online as a tiled map service.

Option B: Use feature collections with map notes in ArcGIS Online

This option is suitable when working with just a few features. Instead of creating a tiled map service, bring the data into ArcGIS Online as feature collections, and label the graphics with map notes in ArcGIS Online. To do this, follow the steps below:

1. Create a zipped shapefile of the feature.
2. Sign in to ArcGIS Online.
3. Go to My Content.
4. Click Create Map.
5. Click Add data from a file, and select the zipped shapefile. The file is added as a feature collection.
6. Click the drop-down arrow next to the shapefile and edit the symbology.
7. Click Add > Map Notes.
8. Select Text, and proceed to add text elements.


Note:
Map notes are not dynamically labeled and users must create each map note for each feature.

For credit consumption in ArcGIS Online, visit the following ArcGIS Online Help page, Service Credits Overview. For more information, please refer to the following ArcGIS Blog post, Workflows for building and hosting cached map tiles in ArcGIS.

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