The following post was written by Simon Woo, a product engineer on the geodatabase team specializing in Raster support in the geodatabase.
Previous versions of ArcGIS have provided various mosaicking workflows. We’ve tried to make the mosaicking experience better in each version, but have had varying feedback on performance, especially when outputting to a file format.
Prior to ArcGIS 9.3, the workflow to create a mosaic was to create a raster dataset and then use the Workspace to Raster Dataset tool to populate the new dataset.
In ArcGIS 9.3, we have provided a new workflow to make your mosaicking experience faster.
The new workflow is to:
- Create an unmanaged raster catalog with the Create Raster Catalog tool.
- Load all the raster datasets into the unmanaged raster catalog with the Raster to Geodatabase tool.
- Use the Raster Catalog to Raster Dataset tool to mosaic the datasets together.
From the tests that we have run, this new workflow is considerably faster. Below are a couple examples of comparison tests that have been run.
Mosaic Test 1
Here’s the test data we used:
Type of data: 3-band
Input format: TIFF
Number of files: 20
Average file size: 38.8 MB
Output format: TIFF
Using the old workflow of creating a raster dataset and then using the Workspace to Raster Dataset tool, this data took 1 hour and 35 minutes to mosaic.
Here are the steps with the new workflow:
First create an unmanaged raster catalog.
This creates an unmanaged raster catalog. Now load the data into the new unmanaged raster catalog:
Now use the Raster Catalog to Raster Dataset tool to mosaic the rasters in the unmanaged raster catalog into a single raster dataset.
We conducted a similar test using GRID data and it yielded the following results:
Mosaic Test 2
Type of data: single band data
Input format: GRID
Number of files: 60
Average file size: 5.7 MB
Output format: GRID
Old Workflow – 45 minutes
Create Raster Dataset time: 1 second
Workspace to Raster Dataset time: 45 minutes
New workflow – 4 minutes
Create Unmanaged Raster Catalog: 1 second
Raster to Geodatabase tool: 1 minute
Raster Catalog to Raster Dataset tool: 3 minutes
The new workflow is shown in model form in the following graphic: