Tag Archives: mosaic
Can I avoid using the internal overviews when I add rasters to my Mosaic Dataset?
Many of the menus and processes, such as the new geoprocessing toolset for example, have changed in ArcGIS 10.0. One of the biggest changes in ArcGIS 10.0 is the switch from Image Server to Mosaic Datasets.
Previously, in Image Server, you could use the Advanced menu to manually control the options when adding rasters to an image service.
However, there are several situations where rasters added to an ISDEF should not apply the internal overviews that are present with some raster formats. SIDs, and other rasters with multiple levels of pyramids, can affect the performance of image services. Since image services use overviews to increase performance, increasing the number of overviews will improve the performance.
When SIDs are added to an image service with the Advanced process under the General Tab, there is an option to “Include internal overviews”. If this option is unchecked the raster will be added without bringing in the pyramids that are in the raster. For highly compressed rasters like SIDs, there can be many levels of overviews built into the raster which affects the number of overviews created by the mosaic dataset or ISDEF.
In order to replicate the same workflow in ArcGIS 10.0, the Add Rasters To Mosaic Dataset tool includes a section of Raster Pyramid Options. In order to prevent the internal pyramids from being added to the mosaic dataset, set the value to zero (0). This increases the number of overviews that will need to be created, but the performance should be improved. If this option is not used, the overviews that are inherent with the SID will be used in place of overviews. So, the choice from a design perspective is whether to utilize the overviews of the rasters added to the mosaic dataset or to create new overviews for the mosaic dataset. This pyramid option is available for all raster formats, not just SIDs.
Add Rasters to Mosaic Dataset dialogue with Raster Pyramid Options
To recap, the ability to apply or ignore the internal pyramids and pyramids of input rasters is available in the Raster Pyramid Options section of the Add Raster to Mosaic Dataset tool.
Jeff S. - Geodata Raster Support Analyst
Do Your Rasters Know What Time It Is?
Viewing a series of rasters according to a timeline usually ends with turning on/off the layers to produce the desired visual affect. This process, along with many other techniques for looking at data over time, has been fairly challenging.
In ArcGIS 10, the ability to time-enable spatial data has opened a whole new dimension to the visualization of information.
Imagery, temperature and precipitation are just a few examples that can be placed into a mosaic dataset or raster catalog to represent a change over time. The following example enables time on a mosaic dataset. However, similar steps can be followed to activate time on a raster catalog.
Preparing your data:
1. Create a new mosaic dataset and add in the rasters.
(For detailed steps see: The workflow and tools to create mosaic datasets)
2. Open the attribute table of the mosaic dataset footprint.
3. Add a new ‘date’ type field.
4. Populate the field with the corresponding time values.
Enabling time on your data:
1. Right-click on the mosaic dataset in ArcMap > Properties > Time tab.
2. Select the Time Field.
3. Click Calculate to populate the time step interval and the layer time extent.
4. Adjust the time step interval to the desired value.
5. Click OK.
6. Open the Time Slider window from the Tools toolbar.
7. Enable time on map from the Time Slider window.
8. Use the time slider to step through each raster in the mosaic dataset.
Now with time enabled functionality, your rasters can know what time it is and provide you with an excellent option for visualizing data changes over time.
-Timothy H., Support Analyst – Geodata Raster Group, Esri Support Services – Charlotte, NC
Related Links:
How time is supported in spatial data
Is your raster so bright you have to wear shades?
Have you ever added a raster to an MXD and noticed that it looked different? Or created a mosaic dataset or raster catalog and suddenly, the rasters are so bright, you think, “What did ArcMap do to my raster?!”
Raster Catalogs can be used for Mosaic Datasets… Really? How?
Hello Support Services blog readers. My name is Jeff, and I am a member of the Geodata Raster team at the East Coast Esri Support Services office located in Charlotte, NC. You may have read one of my previous blogs on mosaic dataset overviews or where to find data on the Web to use in your analysis. Today, I want to discuss the raster types in mosaic datasets in ArcGIS 10.
You will encounter the raster type option when adding rasters to the mosaic dataset via the Add Rasters to Mosaic Dataset tool. There are a plethora of raster type options available to be added. So many, in fact, that some may not be that obvious.
Many of the options refer to particular sensors that require specific settings to interpret and handle the format. There are a few that refer to the different data types available to be added, particularly Image Service Definition, Image Service Reference, Table, and Web Services. Hidden among the sensors is the least obvious raster type titled ‘Table’. This raster type is the setting that can be used to add raster catalogs. The Web Help documentation on this raster type says to use this type when adding the following to your mosaic dataset:
- Raster catalog
- Mosaic dataset
- Table with paths
- .dbf file (for example, from a footprint shapefile)
Each of the items in the raster catalog will become an item in the mosaic dataset. This is different than a referenced mosaic dataset, because you will be able to create overviews. Overviews cannot be created for a referenced mosaic dataset. Once the raster catalog has been added, the normal mosaic dataset process can be utilized.
This workflow should allow you to convert raster catalogs to the mosaic dataset and allow you to gain all the functionality of mosaic datasets. I hope you find these tips helpful when working with raster types in mosaic datasets. Please leave any comments you may have in the ‘Comment’ section below this blog post. NOTE: You must be logged in to your Esri Global Account to leave comments.
- Jeff S., Support Analyst, Geodata Raster team, ESRI Support Services
To Mosaic or not to Mosaic?
Hi, my name is Jeff, and I am a member of the Geodata Raster team at the Eastern ESRI Support Services located in Charlotte, NC. I posed the question above because whether to mosaic or not is one of the most common workflow questions when dealing with rasters. There are many raster formats and depending on the format and the ultimate data product, the answer may change. Some immediate questions to ask are:
- Am I looking to create a backdrop for a map or provide imagery capable of being analyzed?
- Are the rasters highly compressed, for example .sid or .ecw?
- Is file storage a concern for the mosaic? How much room do I have for the mosaic?
There are many more specific questions to consider, but these general questions can prevent future headaches when determining if creating a mosaic is the best course of action.
The mosaic process can create one file that contains several other rasters, but the creation of it can be time consuming and problematic. Plus, there are plenty of other situations where an unmanaged raster catalog may provide the functionality you desire without changing the format or creating a new file.
If you are looking for the ease of adding one file to a map document rather than multiple files or are looking to maintain the format of your compressed raster data, then an unmanaged raster catalog may be the answer. The unmanaged raster catalog resides in a geodatabase and will maintain the extents of all of the rasters added to it, but will not import the rasters. They will maintain the format and then can be added all at once to a map document by simply adding the raster catalog. The unmanaged raster catalog will maintain the location of the original file. This workflow can be particularly handy if you have a large number of SID files that have a file size of 1 gig but an uncompressed size of 20 gigs. A mosaic of several SID files would be considerably large, but the unmanaged raster catalog can utilize the files as they are and load them together at once.
The creation of an unmanaged raster catalog is much quicker than creating a mosaic and can be a great way to display a large number of rasters.
While unmanaged raster catalogs cannot be used for analysis in many of the geoprocessing tools, they can be used for digitizing and backdrops for many different maps.
Below are a few Web Help documents that pertain to this discussion:
Creating a Raster Catalog
Mosaicking Raster Datasets
Exploring Geodatabase Raster Catalogs
- Jeff S., Support Analyst, Geodata Raster team, ESRI Support Services
