Use image space analysis to work with oblique imagery

Available with Image Analyst license.

When a sensor collects an image, it captures the scene in perspective geometry. For remotely sensed images, this geometry is described in a sensor model that accompanies the image in the metadata. In perspective mode of the map view you can display oblique imagery in an image coordinate system (ICS), called image space, rather than a map coordinate system, to enable more intuitive image interpretation.

Working with oblique imagery in image space facilitates seamless transformation between the ICS and map coordinate system to display, interpret, collect, and edit GIS feature data on the perspective imagery.

In perspective mode, also called image space mode, you can visualize the imagery intuitively from the perspective of the sensor. Collecting and editing features in image space leverages the existing editing tools; you can edit using the Edit tab. Additionally, you can perform point, line, and area image mensuration; make vertical measurements; and capture heights of structures in image space based on provided sensor model information and metadata.

In this workflow, you'll visualize imagery, capture data, and perform vertical measurements on imagery in perspective mode. The workflow has the following five steps:

1. Download sample data
2. Activate the image space
3. View your imagery
4. Edit features
5. Make vertical measurements

Download sample data

Download samples of oblique satellite imagery and other data supporting the image space analysis workflow.

1. In a web browser, open the Image Space Analysis sample data website.
2. Click the Download button in the upper right corner. Optionally right-click the .zip file and click Download.
3. Once the download is complete, unzip the .zip file, and move the sample data directory tree to your C:\ directory.
4. Confirm that the C:\SampleData\DG-Rio\ directory tree exists.

The sample data is ready to be used in your image space analysis workflow

Activate the image space

To activate the image space, complete the following steps:

1. Browse to C:\sampledata\dg-rio\ProProject and double-click the Rio-ImageSpaceAnalysis.aprx project file.

   ArcGIS Pro sets up the project environment and loads the imagery and feature class layers in the Contents pane. The imagery is displayed in standard cartographic map view, with north at the top.

   

   WorldView-2 satellite imagery courtesy of DigitalGlobe

2. Make sure the Contents pane appears with the five layers.

   

3. In the Contents pane, click the List By Perspective Imagery button .

   The images are sorted based on focusable images. Focusable images are those eligible for display and analysis in image space as determined by required metadata associated with the imagery.

   

The focusable images are listed first under Focusable Images followed by other layers in the Contents pane.

View your imagery

To view your imagery in the image space map view, complete the following steps:

1. Select the Multispectral_15AUG31133528-M1BS-056845469010_01_P003 layer in the Contents pane.
2. Click the Set as focus image Off button to activate the image space view.

   The focus image button switches to Set as focus image On . The image no longer appears distorted, and can visualize the imagery from the perspective of the sensor.

The map will have a heads-up display (HUD) window overlaid, which displays commonly required metadata pertaining to the imagery you're working with.



WorldView-2 satellite imagery courtesy of DigitalGlobe

3. Optionally, minimize the HUD using the minimize button.
4. Move the pointer to the edge of the HUD to change the pointer type to a move pointer, which allows you to move and place the HUD anywhere on the map.

Edit features

To edit features in image space, complete the following steps:

1. Select the Panchromatic_15AUG31133528-P1BS-056845469010_01_P002 layer in the Contents pane.
2. Click the Set as focus image Off button to activate the image space.

   The button switches to Set as Focus Image On .

3. Click the Map tab, click the Bookmarks drop-down arrow, and select the Airport bookmark.

   The imagery is positioned in the image space view and ready to collect features.

4. Click the Edit tab to view all the editing tools.
5. Click the Create tool button in the Features group

   The Create Feature pane appears.

For more information about editing, see A quick tour of editing.
6. In the list, click the feature class where you want to save the edits.
7. Click the Polygon tool button , and digitize some buildings.
8. Repeat steps 5 through 7 for each building you want to digitize.
9. Once you finish collecting your features, click the Save Edits button.

Make vertical measurements

To measure the height of features, complete the following steps:

1. Confirm that the image layer is active in the Contents pane.
2. On the Imagery tab, click the drop-down arrow to access the mensuration tools, which are located in the Mensuration group.

   

   The enabled tools depend on the metadata of the image layer selected in the Contents pane. For example, metadata needs to include sun angle and acquisition date to use the shadow measurement tools. See Making measurements using imagery for a table that outlines the metadata information required to enable each mensuration tool.

3. Click the Top To Top Shadow Height tool button .
4. Set two points—the first at the top of the tower structure and the other at the top of the shadow of the tower structure — as shown in the following image:

   

   WorldView-2 satellite imagery courtesy of DigitalGlobe

   The measurement result is shown on the map, along with the graphic. Review the measurement details in the Mensuration Results pane. Metadata associated with the image and measurement is also displayed.

   

5. Select a measurement from the table, and press the F2 key to rename the measurement Name in the Mensuration Results pane.
6. Add a measurement description in the Description text box in the pane.
7. Click the Generate Report button to export the mensuration results to a text file on disk.

   Measurements are automatically saved in a feature dataset in the project geodatabase. The measurements are loaded automatically into the Mensuration Results pane when a project is loaded.

   

8. Optionally click the options button in the Mensuration group to specify an elevation file to improve measurement accuracy. Browse to C:\sampledata\dg-rio\DEM and select the WorldSRTM30m.mrf file.

   

In this workflow, you learned how to visualize, capture data, and make measurements in the image space analysis environment.