Exercise 7: Adding a satellite sensor raster type to a mosaic dataset

This topic applies to ArcEditor and ArcInfo only.

Complexity: Intermediate Data Requirement: ArcGIS Tutorial Data Setup Data Path: C:\arcgis\ArcTutor\Raster\Data Goal: Learn how to add the Landsat 7 ETM+ raster type to a mosaic dataset.

In this exercise, you will create a mosaic dataset containing a Landsat 7 ETM+ scene using geoprocessing tools within ArcMap. This will be a multiband, pan-sharpened mosaic dataset. You will edit the raster type's properties to modify some default parameters that are applied when adding this data to the mosaic dataset.

This exercise does not rely on any previous exercises.

Before you begin, it is assumed that you have installed the tutorial at C:\arcgis\ArcTutor\Raster\Data. If not, make the appropriate path changes throughout this tutorial so it works properly for you.

The data provided in the Landsat_p114r75 folder comes from Landsat.org/Tropical Rain Forest Information Center, a member of NASA's Federation for Earth Science Information Partners (ESIP) at Michigan State University (http://www.landsat.org/).

Start ArcMap

Steps:

1. Start ArcMap by clicking Start > All Programs > ArcGIS > ArcMap 10.
2. Click Cancel on the ArcMap - Getting Started window.

   This window may not open if you've previously opted not to show it.

   Note:

   You will be setting the default map document's geodatabase later in this exercise.

Create a file geodatabase

If you have already created ImageGDB in another exercise, you can skip this section of steps.

Steps:

1. Click the Catalog window button on the Standard toolbar.

   This opens the Catalog window.

2. In the Location text box, type C:\arcgis\ArcTutor\Raster and press ENTER.

   This location is added to the Catalog tree under the Folders Connection heading.

   If your tutorial data was installed in a different location, alter the path according to your installation location.

3. Right-click the Raster folder and click New > Folder.
4. Name the folder Exercises.
5. Right-click the Exercises folder and click New > File Geodatabase.
6. Rename the new file geodatabase ImageGDB.

Set the default geodatabase

Each map document has a default geodatabase, which is the home location for the spatial content of your map. This location is used for adding datasets and saving resulting datasets created by various editing and geoprocessing operations.

Learn about the default geodatabase

Steps:

1. Right-click the ImageGDB geodatabase in the Catalog window and click Make Default Geodatabase.

Create a new mosaic dataset

Create a mosaic dataset to add the Landsat imagery that will be pan-sharpened.

Steps:

1. Right-click the ImageGDB in the Catalog window and click New > Mosaic Dataset.

   This opens the Create Mosaic Dataset tool dialog box.

2. Type LandsatPS in the Mosaic Dataset Name text box.
3. Click the Coordinate System browse button .
4. Click Select.

   Do not click Import as the internal spatial reference of the files you will be adding are referenced to the wrong hemisphere.

5. Double-click the Projected Coordinate Systems folder, double-click the UTM folder, double-click the WGS 1984 folder, double-click the Southern Hemisphere folder, choose WGS 1984 UTM Zone 50S.prj, then click Add.
6. Click OK to close the Spatial Reference Properties dialog box.
7. Click OK on the Create Mosaic Dataset tool dialog box.

   If the reporter window opens, click Close once the process is complete.

   The LandsatPS mosaic dataset is created in the geodatabase and added to the ArcMap table of contents. This is an empty mosaic dataset. It is added as a mosaic layer, which is a special group layer. The top level has the name of the mosaic dataset—LandsatPS. There are also empty Boundary, Footprint, and Image layers. You will add the Landsat imagery to it in the next steps.

Add rasters to the mosaic dataset

Steps:

1. Right-click the LandsatPS mosaic dataset in the Catalog window and click Add Rasters.

   This opens the Add Rasters To Mosaic Dataset tool dialog box.

2. In the Raster Type list, choose Landsat 7 ETM+.
3. Click the Properties button .

   The Raster Type Properties dialog box opens. Here you will enter information to define how the data will be added and any processing that will be applied, such as the bands that will be added and the enhancement that will be applied to the data.

4. Click the General tab.
5. Click the Processing Templates drop-down arrow and click Pansharpen.

   The processing templates define how the data will be added to the mosaic dataset; for example, the template you select creates a multiband image that is pan-sharpened once you zoom in to the pixel level of the higher-resolution panchromatic band.

6. Click the Properties tab.

   Here you can modify some of the defaults. For example, you can modify the band combination by changing the order or removing some of the bands. The band combination is defined by a space-delimited list. You can also modify the type of histogram stretch you want applied and the type of pan-sharpening.

7. Type 1.5 in the Percent Clip Minimum and Percent Clip Maximum text boxes.
8. Check the 4th-band as infrared image check box.

   This ensures that the fourth band is calculated in the pan-sharpening algorithm.

9. Click Apply.
10. Click the Functions tab.

    This tab displays the functions that are applied based on the processing template that you chose on the General tab. You chose the Pansharpen template.

    The functions are applied to the imagery from the bottom of the chain to the top. You can see that the Pansharpen template creates a MS (multispectral) image, then uses the Extract Bands function to define the four bands used in the pan-sharpening algorithm. Both MS and Pan (panchromatic) images are enhanced using the Stretch function. A Convolution function, which is sharpening the Pan image, is applied, then the Pan and MS images are combined using the Pansharpening function.

    You can add or edit the functions in the function chain prior to adding the data to the mosaic dataset. You won't be doing it in this exercise; however, if you do make modifications to the function chain or any of the properties on this dialog box, you can save the changes to a new raster type so you can use it again and be sure to apply the same settings. To save the changes, click the Save As button on the General tab.

11. Click OK.
12. Click the drop-down arrow and click Workspace.

    You only have one image scene to add, so you could point to the single file needed; however, if you're adding multiple images organized into a folder, you want to use the Workspace option.

13. Click the Input browse button .
14. Navigate to C:\arcgis\ArcTutor\Raster\Data, click Landsat_p114r75, then click Add.
15. Check Update Overviews.
16. Click Advanced Options to expand the list of parameters.
17. Check Build Raster Pyramids.
18. Check Calculate Statistics.

    It is generally recommended that you build pyramids and calculate statistics on the data that is added to a mosaic dataset. Statistics improve the display, and pyramids reduce the number of overviews that are generated. By checking these check boxes, the operations are run prior to calculating the cell sizes or overviews. If pyramids or statistics exist for a raster dataset, they are not regenerated.

19. Check Build Thumbnails.
20. Type Pan-sharpening Landsat imagery in the Operation Description text box.

    This parameter allows you to add descriptive text to the log that is maintained by the mosaic dataset.

21. Click OK to run the tool.

    If the reporter window opens, click Close once the process is complete.

    The Landsat 7 ETM+ satellite image is added to the mosaic dataset. The footprints are created for each raster dataset, and the boundary is generated for the entire mosaic dataset. The overviews are then generated for the entire mosaic dataset.

22. You may need to click the Full Extent button to view the mosaic dataset.

Change the band combination

By default, the bands are displayed in the order they were added to the mosaic dataset. Therefore, the default band combination is 1, 2, 3 for red, green, and blue.

Steps:

1. Right-click Image in the table of contents and click Properties.

   The Layer Properties dialog box for the mosaic dataset image is opened.

2. Click the Symbology tab.
3. Click the drop-down arrows to change the band combination to 3, 2, 1.

4. Click OK.

A natural or true-color image is displayed.

Examine the tables

There are three main tables that are maintained with all mosaic datasets: the Attribute table, Logs table, and Raster Type table. The Attribute table contains specific metadata information for each raster dataset in the mosaic dataset. You can also add and populate fields. These fields can be used when defining a query on the mosaic dataset (or image service). If you don't want all the fields exposed to those using the mosaic dataset, you can edit Allowed Fields on the Mosaic Dataset Properties dialog box. The Logs table maintains a list of every action that was performed on the mosaic dataset, such as adding data, creating service overviews, and removing data. The Raster Type table maintains a list of all the raster types used to create the mosaic dataset.

Steps:

1. Right-click LandsatPS in the ArcMap table of contents and click Open > Raster Type Table.

   There are two rows in this table. The first row (OBJECTID = 1) identifies the Landsat 7 ETM+ raster type that you used to add the data to the mosaic dataset. The operation description you added is displayed in the Description column. The second row (OBJECTID = 2) identifies that there are overviews generated for this mosaic dataset and the time at which they were created.

2. Close the table.
3. Zoom in to your mosaic dataset so you're viewing it at approximately a 1:200,000 scale.
4. Right-click LandsatPS in the ArcMap table of contents and click Open > Attribute Table.

   You should see four rows in the table. The name of the rasters or their source datasets are listed in the Name column. If you scroll across the table, you will see the Tag column. The Tag column is associated with the sources identified in the Pansharpen function chain. The MS tag represents the multispectral image, and the Pansharpened tag represents the pan-sharpened image.

   MinPS and MaxPS indicate the pixel resolutions where the images will be displayed. There are only two overview images. These can be identified by the Ov_ prefix in their name. When you view the image at its full extent, the bottom overview image is displayed, and as you zoom in, requiring a higher pixel size, you see the image above it in the table. Next you see the source imagery identified by the MS tag. This is displayed when you are viewing an image at a pixel resolution between 28.5 meters to 342 meters. When you zoom in to a pixel resolution smaller than 28.5 meters, you view the pan-sharpened image.

5. Type 80000 into the scale box on the Standard toolbar.

   You are viewing the pan-sharpened image.

   You can see some artifacts in the pan-sharpened image that were not present before. This is because the panchromatic image has some artifacts that the convolution filter is enhancing.

6. Click the row under the Raster column representing the pan-sharpened image.

   A gray button appears.

7. Click the gray button.

   This opens a window allowing you to preview the raster image, its properties and metadata, and the function chain used to generate the image.

8. Click the Functions tab.

   You see the same function chain that was displayed when you were adding imagery to the mosaic dataset. The only difference is there are specific files listed where earlier you saw MS and Pan.

9. Right-click Convolution Function and click Properties.
10. Click the Convolution tab.
11. Click the Type drop-down arrow and click Smooth Arithmetic Mean.

    This filter removes the artifacts that the Sharpen type was enhancing.

12. Click OK to close the Raster Function Properties dialog box.
13. Click Apply.

    The display is updated and the artifacts are removed, resulting in a much nicer image.

14. Close the table window.

Properties and metadata

Steps:

1. In the Catalog window, right-click the LandsatPS mosaic dataset and click Properties.

   The Mosaic Dataset Properties dialog box opens. Here you can view the properties for the entire mosaic dataset, including the setting that will affect how users interact with the dataset. You can also edit functions that will be applied to the entire mosaic dataset.

2. Click the Defaults tab.
3. Click the ellipsis button next to the Allowed Mosaic Methods row.

4. Uncheck Seamline, as no seamline is created as part of this exercise.
5. Click OK.
6. Click the ellipsis button next to the Allowed Fields row.

7. Uncheck the following: Name, LowPS, HighPS, GroupName, ProductName, ZOrder, SOrder, StereoID, Shape_Length, and Shape_Area.

   If you serve this dataset as an image service, only the fields checked will be accessible.

8. Click OK to close the Mosaic Dataset Properties dialog box.
9. In the Catalog window, right-click the LandsatPS mosaic dataset and click Item Description.

   The Item Description dialog box is opened. Here you can view or edit metadata information for the mosaic dataset.

10. Click the Preview tab.
11. Click the Create Thumbnail button .
12. Click the Description tab.

    The thumbnail you created is displayed on this tab.

13. Click the Edit button .
14. Type Landsat image in the Title text box.
15. Type Landsat 7 ETM+ image within Australia in the Summary text box.
16. Type your name in the Credits text box.
17. Click the Save button .
18. Close the window.

You have completed creating a mosaic dataset, adding data, and modifying the properties and metadata. You can share the ImageGDB location to make this mosaic dataset available within your organization, or serve this mosaic dataset as an image service using ArcGIS Server.