Feature Analyst Quick Start Guide

Transcription

1 Feature Analyst Quick Start Guide River Extraction River extractions are much like road extractions, in that you are trying to identify a continuous object running through other features within your image. Feature Analyst provides you with an end to end solution for extracting your river features. This document provides general instructions for completing a river extraction. River Extraction Work Flow Create a new training set (shape file) highlighting representative river segments. If necessary, use the Convert to Line tool to convert the river polygon to a single line. Setup the learning parameters and run the extraction. Commit data to your geodatabase. Refine results as needed using Post Processing/Hierarchical Learning to obtain the final results or use the ArcGIS editing tools to manually remove unwanted polygons. 9LVXDO/HDUQLQJ6\VWHPV,QF 32%R[ 0LVVRXOD07

2 River Extraction Feature Analyst Quick Start Creating Training Sets To get a good representation of the target feature class, remember to create examples throughout the image. 1 Choose the Create New Feature Layer tool. The Feature Analyst Save As dialog box opens. 2 Select a path in the list box in the center of the dialog box. 3 Enter a name for the new layer in the Filename field. 4 At the bottom of the dialog box, select Polygon Shapefile. Note: Though Feature Analyst can work with Point and Line feature layers, it works best with Polygons. 5 Choose Save. The new feature layer appears in the Table of Contents. 6 Choose Editor on the ArcGIS toolbar and select Start Editing on the drop menu. This starts your editing session. 7 Choose the Sketch tool on the ArcGIS toolbar. 8 Using the zoom tools, zoom in on the image and draw a sample polygon. 9 Repeat the previous step until you have adequate training examples. In the image below, the river training polygons appear in the white squares. [ 2 ]

3 Feature Analyst Quick Start River Extraction Setting Up Parameters 1 Choose Set Up Learning on the Feature Analyst toolbar. The Set Up Learning dialog box opens. 2 On the Feature Selector tab, choose Wide Linear Feature from the pre-defined parameters. 3 Choose OK. 4 Choose One Button Learning on the toolbar to start the extraction pass. The Feature Analyst Save As dialog box opens. 5 Enter a name and path for the new shape file. 6 Choose Save. The system runs the training pass and returns the results to the active data frame in the Table of Contents. Removing Clutter Manually If your results come back fairly clean with only a minimal amount of clutter, we recommend manually remove the extra polygons using the editing tools available in ArcGIS. 1 Choose Editor on the ArcGIS toolbar and select Start Editing on the menu. 2 Choose the Edit tool on the toolbar. 3 Select your result layer in the Target field. 4 Click on an incorrect polygon in the layer and press the Delete button on the keyboard. 5 Continue highlighting and deleting polygons until you have removed all the incorrect polygons from the result layer. The completed result layer provides you with double-drain river polygons. Removing Clutter Automatically If your results come back with a significant amount of clutter, we recommend using the Hierarchical Learning and Post Processing [ 3 ]

4 River Extraction Feature Analyst Quick Start features of Feature Analyst to clean up your polygons. Using the automatic clutter removal features adds those processes to your learning recipe, allowing you to use them on similar river images. Feature Analyst provides several Hierarchical Learning tools for cleaning up polygons. For river extractions, we recommend trying Aggregate Features first to remove small polygons that are not part of the river. Aggregating Features 1 Highlight the result layer in the Table of Contents and choose Feature Analyst on the toolbar. 2 Select Post Processing on the drop menu and select Aggregate Features on the Post Processing menu. The Aggregate Features dialog box opens. 3 In the Minimum Polygon Area field, enter a number representative of your river. This number should be high enough that it excludes any objects smaller than your continuous river polygon. 4 Choose OK. The Feature Analyst Save As dialog box opens. 5 Enter a name and path for the aggregation shape file. 6 Choose Save. Feature Analyst eliminates the small polygons. Converting Polygons to Lines If your specifications call for a single line drain, you can convert your polygon results quickly to a line result using Feature Analyst's Convert to Line feature. 1 Highlight your final polygon result layer in the Table of Contents. 2 Choose Feature Analyst on the toolbar, select Post Processing on the menu, and then select Convert to Line on the Post Processing menu. [ 4 ]

5 Feature Analyst Quick Start River Extraction The Convert to Line dialog box opens. 3 On the Convert to Line dialog box, set the following parameters: Clear the Polygons Represent Road Networks check box Gap Jumping Dangle Removal Intersection Rework You can allow Feature Analyst to optimize the settings for you by using the Let Feature Analyst Determine Length settings. 4 Check the Smooth Results check box and choose Smooth Settings. The Smooth Features dialog box opens, allowing you to customize the smoothing parameters. 5 Select Bezier in the Select Smoothing Algorithm field. 6 Choose Modify Algorithm s Parameters at the bottom of the dialog box. The Bezier Smooth options dialog box opens. 7 In the Number of Vertices field, enter the number of vertices you want the system to look at to determine the best midpoint to create a straight line. We recommend a setting between 3 and 5. 8 In the Max Distance field, enter the maximum distance you want the system to move a vertex. This indicates the maximum number of pixels to move any vertex. If the vertex lies outside this maximum, the system leaves it in place. 9 Choose OK three time to return to the work space and start the smoothing pass. The Feature Analyst Save As dialog box opens. 10 Enter a name and path for the new layer and choose Save. The system converts the polygon shapes to line features and displays the new layer in the Table of Contents. [ 5 ]

6 River Extraction Feature Analyst Quick Start Feature Analyst provides an additional tools for cleaning up line features. See your online help system for more information in the Deluxe Line Reshape Tool and the Intersection Repair Tool. Create Shape File Metrics The Shape File Metrics feature allows you to calculate a variety of metrics for the polygons in your result layers, on the fly. The calculations are entered into the Attributes table for the layer. The feature works on points, lines, and polygons. With point results, you can only select the Mean Height option. To accomplish this, you must have a DEM file for the active data frame. With line results, you will only have access to the Length option. 1 In the Table of Contents, highlight the result layer you want to calculate on. 2 Choose Feature Analyst on the toolbar and select Feature Tools on the drop menu. 3 Select Create Shape File Metrics on the Feature Tools menu. The Create Shape File Metrics dialog box opens, allowing you to select the inputs to calculate for. 4 Select Length. Since you are calculating a line feature, this is the only option available. 5 Choose OK on the dialog box. The Feature Analyst Save As dialog box opens, asking you to name the new shape file created from this action. 6 Enter a name and path for the new file and choose Save. Feature Analyst calculates the attributes you selected. The system enters the metrics into the Attributes Table. Viewing Results Once you have calculated your shape metrics, you can view the calculations in the Attribute Table. 1 Right-click on the layer you calculated the metrics for. 2 Select Open Attributes Table on the popup menu. [ 6 ]

7 Feature Analyst Quick Start River Extraction The Attributes table opens, displaying the metrics for the features in the selected shape file. 3 Click the close button (X) to close the dialog box. Commit to Geodatabase Now that you have acquired your complete results, you may want to commit the new geographic data to your geodatabase. WARNING: Make sure that the coordinate systems for both your source and target match. If not, the Commit to Geodatabase tool might not produce the expected result. 1 Choose File on the menu bar and select Add Data from the drop menu. The Add Data dialog box opens, allowing you to find your geodatabase and open the feature class file you want. 2 Browse to the desired Geodatabase and select the appropriate feature class and choose Add. The selected feature class appears in the table of contents in the data frame. 3 Choose Editor on the ArcGIS toolbar and select Start Editing. The Start Editing dialog box opens, asking you to identify the layer to edit. 4 Select the geodatabase from the list and choose OK. [ 7 ]

8 River Extraction Feature Analyst Quick Start 5 Choose ArcGIS Selection tool on the ArcGIS toolbar and draw a stretchy box around the features you want to include in your geodatabase. To select all available features right click on your results shape files, choose Selection, then choose Select All. 6 Highlight the shapefile in the TOC that contains the results you want to commit to the geodatabase. 7 Choose Feature Analyst on the toolbar, select Post Processing from the drop menu, and select Commit to Geodatabase on the Post Processing menu. The Commit Data dialog box opens. The feature class you selected previously is highlighted, along with any sub-types attached to the selected class. 8 Verify that the appropriate shape file is listed in the Selected Feature Layer box at the top of the Commit dialog and that the Count reflects the number of features that you want to write to the geodatabase. 9 In the Available Feature Classes box, select a feature class. 10 Choose OK. The system applies the default attributes specified in the geodatabase to the features selected in the workspace. Setting Custom Attributes You can use the Available Feature Classes to fill in the attributes for your features. You can also use them as a short cut to filling in the attributes. You can select a feature class in the list and then edit the attributes that are unique to the data you are working with. 1 Follow steps 1 to 5 above to assign default feature class attributes. 2 Choose Set Custom Attributes. The Attribute Editor dialog box opens over the Commit to Geodatabase dialog box, allowing you to edit the individual data fields. [ 8 ]

9 Feature Analyst Quick Start River Extraction Some fields only allow you to select information already assigned to the field. These are called Domain fields and are limited to the assigned domain data. 3 In domain fields, select an option from the list provided. In non-domain fields, enter your required information. Nondomain fields allow you to enter any information you need. 4 Choose OK on the Commit to Geodatabase dialog box. The dialog box closes and you return to the ArcGIS workspace. Confirming Attribute Assignment 1 Right click the final result layer in the Table of Contents. 2 Select Open Attribute Table from the popup menu. The attributes assigned from the feature class selection appear in the table cells. [ 9 ]

10 River Extraction Feature Analyst Quick Start [ 10 ]