An imagery mosaic is a container that allows multiple imagery sources to be processed as one unit. A mosaic maintains its constituent images intact, without masking or feathering the edges where they meet. Only the external edges of the mosaic are masked and feathered.
This article covers deciding when to create a mosaic, creating a mosaic, and modifying a mosaic.
Deciding when to create a mosaic
If you have a collection of images whose edges perfectly abut each other, it's often a good idea to create a mosaic before adding the images to a layer. For example, imagery for a city might include a number of images. If you add those images directly to a layer, their edges are feathered, and some detail may be lost. However, if you add the images to a mosaic first, the edges of the individual images where they meet are maintained.
Mosaics are meant for contiguous images. Although technically, you can create a mosaic from non-contiguous images, there wouldn't be a reason to do so.
The images in a mosaic must match in the following ways:
- resolution
- projection
- number of bands
- standard North/South orientation
Creating a mosaic
To mosaic images, you should first tag the images, then do a search, and then add all the search results to a mosaic.
You'll need to fill in the following information.
| Name | The name of this mosaic. |
| Description | A text description for this mosaic. This description will be visible only within Google Maps Engine and not to external viewers of a map that includes this mosaic. |
| Tags | The text strings in response to which you want this mosaic to be found. |
| Sharing settings | The access list to which you want to grant permission to work with this mosaic. |
| Attribution | Acknowledgment for the source of the imagery. |
When the mosaic is processed, you can add it to a layer as you would any other image data source.
Modifying a mosaic
You can add images to a mosaic and remove images from a mosaic. When you make changes to a mosaic, you must reprocess the mosaic and reprocess any layer that contains the mosaic.
