Display imagery

Using the map viewer, you can create and display your imagery on the web. As the author of a map, you decide how the imagery in the map is presented.

When you add an image layer to a map, the map initially uses the default display settings of the image service. If you want to change the appearance and ordering of the images in the display, you can change the image display, the image display order, and the image quality.

Image display

You can change the image display by using a predefined template or setting the band combination and stretch parameters.

Use a predefined template

When you publish an image service, you can predefine the image display with templates. You might use a predefined template for several reasons:

• Display a clear view of the data.
• Display the images without clouds.
• Highlight certain features within the image.

You can choose any of the predefined templates to use with the map.

1. Verify that you are signed in and have privileges to create content.

   Tip:

   If you do not have privileges to create content, you can still change the imagery display by clicking Modify Map.

2. Open the map in the map viewer, click Details, and click Contents.
3. Browse to the feature layer you want to display imagery, click More Options , and click Image Display.
4. Click the Renderer drop-down arrow and choose the display template you want to use.
5. Click Apply to apply the template to the map. The template cannot be edited within the map.

Use the user-defined renderer

The band combination allows you to specify which bands are displayed using the red, green, and blue color composite scheme. The different color combinations display your imagery with various color effects. You can display your data in a natural color (red, green, and blue), which displays the layer as you would normally see it. Other color combinations can highlight vegetation, urban areas, water, and other features.

The stretch parameters improve the appearance of your image by using various contrast enhancements. The following contrast enhancements determine the range of values that are displayed.

• None—No additional image enhancements will be performed.
• Minimum and Maximum—Display the entire range of values in your image.
• Standard Deviation—Display values between a specified number of standard deviations.
• Percent Clip—Set a range of values to display. Use the two text boxes to edit the top and bottom percentages.

You can also make additional adjustments to the dynamic range adjustment (DRA) and the gamma factor.

• Dynamic Range Adjustment—Performs one of the above stretches but limits the range of values to what is currently in the display window. This option is always turned on if the image service does not have global statistics.
• Gamma—Stretches the middle values in an image but keeps constant the extreme high and low values.

1. Verify that you are signed in and have privileges to create content.

   Tip:

   If you do not have privileges to create content (you won't see Save in the map viewer), you can still change the imagery display by clicking Modify Map.

2. Open the map in the map viewer, click Details, and click Contents.
3. Browse to the feature layer you want to modify, click More Options , and click Image Display.
4. Click the Renderer drop-down arrow and choose a user-defined image display.
5. Adjust the Red, Green, Blue composite with the bands you want to display.
6. Click the Stretch drop-down arrow and choose the stretch type to use.
   • None
   • Minimum and Maximum
   • Standard Deviation
   • Percent Clip
   1. Additionally, adjust any of the parameters for that particular stretch.
7. Click Apply to display the rendering in the layer.

Image display order

An image service published from a mosaic dataset contains one or more images. These images are mosaicked on the fly and behave like a single image when a user browses the service. When creating a map, you select how the map will display for your audience. You can determine the image order and how to resolve overlapping areas. Image order refers to how to select an image when there are multiple images over the same area. You can also determine how to display areas of images that overlap one another.

As the author, you set the Priority Ordering Method; this controls which images are visible and the image order. Images in an image service are visible at certain scales. The visibility range corresponds to the minimum pixel size (MinPS) and maximum pixel size (MaxPS) in the image attributes. The visibility setting is always honored except when the A list of images option is chosen.

• Only scale—Use this option to prioritize the image order by the scale of the images. For images that are at the same scale, the ObjectID within the image attributes determines their display order.
• An attribute—Select an attribute to determine the image order. The image with the highest value according to its attribute will be displayed on top. For example, if you want to show the most recent images, you can display the images based on their acquisition date. Use the calendar to select the acquisition date. Another common attribute to use is the percentage cloud cover to get the clearest image possible.
• Image center closest to the view center—As your audience browses through a mosaicked raster layer, the images that are displayed will change. The images with their image centers closest in distance to the center of the screen display on top. This is useful if your audience is interested in the stationarity of features.
• Fixed order with the most northwest on top—The order is based on the center of each image's distance to the northwest corner of the mosaicked raster layer. Since this presents a static display, it is useful when you do not want the images to change.
• Sensor location closest to view center—Displays the images with the least distortion. When a sensor captures an image, the point directly overhead of the image is known as the nadir point, which tends to have the least distortion. The images with their nadir point closest in distance to the center of the screen display on top.
• Defined seamlines—You need to have seamlines already created if you want your audience to have access to this option. Images are prioritized based on your existing seamlines. If you choose this option, you should use Blend of pixel values to resolve any overlapping pixels.
• A list of images—If you're interested in a small number of images, you can explicitly list them using a comma-delimited list in the order you want them to be displayed. This method bypasses image visibility constraint and forces the listed images to display at any scale, for example, 1, 2, 3.

Check the Reverse the order box to reverse the order the priority sets.

After setting the Priority Ordering Method, there may be instances where two or more images overlap. You can resolve overlapping areas with the following settings:

• Only highest priority—Use the pixel value from the image that has the highest priority as set by Priority Ordering Method.
• Minimum of pixel values—Use the lowest pixel value.
• Maximum of pixel values—Use the highest pixel value.
• Average of pixel values—Use the mean pixel value.
• Blend of pixel values—Use the blend option for overlapping areas to create a smooth transition along seamlines.

1. Verify that you are signed in and have privileges to create content.

   Tip:

   If you do not have privileges to create content, you can still change the imagery display by clicking Modify Map.

2. Open the map in the map viewer, click Details, and click Contents.
3. Select the method to prioritize imagery.
4. Optionally reverse the order, if necessary, by clicking the Reverse the order box.
5. Select the method for resolving overlapping pixels.
6. Click Apply to display the visibility and priority.

Set image quality

There are tradeoffs between performance and image layer quality because they are inversely related. Higher-quality images will be larger files and will affect performance speed. Performance is also dependent on your connection speed. There are several options designed to meet your needs and bandwidth capabilities.

• Performance—Compresses into a JPEG format at 50 percent quality. Assuming the original image has dimensions of 1,034 by 721 (approximately 2 MB), the transmitted size using this option is only 62K. This option does not support any transparency, so areas of no data will be displayed in black.
• Balanced—Compresses into a PNG32 when there are NoData pixels present in the current view and compresses into a JPEG format at 75 percent quality when there are no transparent pixels. Assuming the original image has dimensions of 1,034 by 721 and no transparent pixels, the transmitted size using this option is 99K.
• Quality—Compresses into a PNG32 format when there are NoData pixels present in the current view and creates a JPEG compression at 95 percent quality when there are no transparent pixels. Assuming the original image has dimensions of 1,034 by 721 and no transparent pixels, the transmitted size using this option is 277K.

In general, use the Quality or Balanced option. If you are on a network with low bandwidth, choose the Performance option. Note that choosing Performance will cause transparent pixels to be blacked out.

1. Verify that you are signed in and have privileges to create content.

   Tip:

   If you do not have privileges to create content, you can still change the imagery display by clicking Modify Map.

2. Open the map in the map viewer, click Details, and click Contents.
3. Browse to the feature layer that contains the image quality you want to change, click More Options , and click Image Quality.
4. Use the slider to select the compression level.
5. Click Apply to display the image quality.

Filter images

When you have multiple images in your image service, you can use attribute queries to filter the images displayed. Filtering image layers works similarly to filtering feature layers. For example, if you are working with the entire Landsat archive, but only want to see cloud-free images from Landsat-7 before its scan-line corrector went off, you could do that with a filter. One thing to note about image filtering is that the map scale may affect the visibility of filtered images.

Set multidimensional filter

Use the multidimensional filter to choose which variable to display on the map and to slice the data by configuring dimensions. This type of data is common in oceanographic and meteorological analysis to show patterns in wind speed, ocean currents, and other variables at different elevations, depths, and pressures. Variables represent the subject of observation or prediction, such as water temperature, salinity, and wind speed. Dimensions are used to address the observation or prediction, such as time, depth, and pressure.

1. Verify that you are signed in and have privileges to create content.

   Tip:

   If you do not have privileges to create content, you can still change the imagery display by clicking Modify Map.

2. Open the map in the map viewer, click Details, and click Contents.
3. Browse to the feature layer that contains the multidimensional filter you want to change, click More Options , and click Multidimensional Filter.
4. Select the variable to display from the drop-down list.

   Choose Default to use the variable configured in the service. Default means there is no client-side variable filtering. This can be due to the server having a default variable configured through processing templates, or a processing result derived from multiple variables.

5. Check the dimensions to define the variable and use the calendar or drop-down list to select the values.

   Note:

   You need to disable the time and dimension animations from the layer before you enable the dimensions.

6. Click Apply to display the multidimensional filter.

Change the style of vector field data

Image services with U-V or magnitude and direction information can be symbolized using vector symbols, such as arrows. The symbol size and color represent the magnitude. The angle represents the flow direction.

1. Verify that you are signed in and, if you want to save your changes, that you have privileges to create content.

   Tip:

   If you do not have privileges to create content, you can still change the imagery display by clicking Modify Map.

2. Open the map in the map viewer.
3. Click Details and click Contents.
4. Click the layer name and click Change Style .
5. Make any of the following changes:
   • Symbol—Choose the type of symbol you want to use to display the data. Options include Simple Scalar, Single Arrow, Wind Barbs, Beaufort Wind scale, Ocean Currents with either 4 or 9 classes, and classified arrows. All the symbols except simple scalar use the size or color of the symbol to represent the magnitude of the data and the rotation angle of the symbol to represent its flow direction. Descriptions of each symbol are included in the drop-down list.
   • Direction represents flow—Choose to display the direction of the symbols from meteorological to oceanographic flow. Meteorologists display the data based on the direction from which air is flowing. Oceanographers, on the other hand, display data based on the direction to which water is flowing.
   • Symbol density—Scale the patterns you are observing by moving the slider toward sparse or dense. As you move the slider toward sparse, each symbol will represent a larger area and, therefore, a larger pattern. A denser setting enables you to see patterns that are localized and smaller, as each symbol represents the data over a smaller area.
   • Symbol scaling—Scale the symbols by moving the slider toward minimum or maximum. Use the advanced settings to set a more precise scale range.
   • Advanced Settings—Set a precise range for the symbols by converting the magnitude and setting the minimum and maximum range. These settings affect the minimum and maximum symbol size because the size uses the converted magnitude unit. Limit the range of data that is displayed by setting a minimum and maximum value. Data outside of the range is symbolized using the minimum and maximum values.
6. Click Apply to display your styling.

Dimension settings

Use the dimension slider to select the dimensions you want to animate. Common dimensions include elevation, depth, and pressure. Use any of the following options:

• Dimension selects the dimension you want to use.
• Use Range sets a range of values using the dimension slider. Uncheck this box to work with one slice at a time.
• Playback Speed sets the animation speed.
• Dimension Range is checked on by default and all slices are available for visualization. Uncheck this box to input specific values for the start and end points.
• Interval is similar to a time step; however, it is in the units of the dimension rather than time. For example, when visualizing a variable at different depths, set the Interval to 100 meters to display the layer that represents every 100 meters of depth.

Show table/table options

You can display a table of the image layer. The table has metadata for each image, which can be useful for deciding which categories to use when filtering. You can also use the table to do the following:

• Show selected records/Show all records—Show only the records you have selected from the layer.
• Center on the selection—Center on the selected records in your layer.
• Clear the selection—Clear the images from the selection. They will remain visible on your map and in the table.
• Show/Hide columns—Choose which columns to display in the table.
• Select visible images—Select the images that are visible on the map.
• Display all images—Display all the images from your layer on your map.
• Display selected images—Display only the images you have selected.

When you work with an image service that has a lot of images, you may want to find one or a few particular images to display. You will need to incrementally filter the images you want to display, lock the display to the images you want, then reset the display so no images are selected. This workflow involves the following steps.

1. There are three tools at your disposal for filtering images—You can filter images by applying a filter on the layer, you can use the table to Show Visible Images, or you can click a point on the map when the table is displayed. Once you have filtered images, use Table Options to show the selected records.
2. Refine your selection by clicking records in the table. You can use the Ctrl key to select multiple items. Choose Show Selected Images again using the table options.
3. Use Display Selected Images to lock down the image.
4. Reset the display to show all images by selecting Show All Images or use the Reset button in the layer's image display context menu.

Legend

If your image service is shared on an ArcGIS 10.2 server or later, you can display a legend in your map. The legend shows by default; however, there is an option to hide it.