Advanced editing in a geodatabase_ArcGIS for Desktop Cookbook-QQ阅读女频现言网

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Advanced editing in a geodatabase

The Advanced Editing toolbar offers tools to reshape and replace geometry, correct the overshoot or undershoot errors, split line features in intersection, divide a line or curve based on specified lengths or percentages, and edit multipart features.

The COGO toolbar allows you to work with COoordinate GeOmetry. Coordinate geometry refers to directions or bearings, angles, and horizontal distances that generally came from a topographic survey and that describe a series of consecutive lines. Those lines can be straight lines or simple curves and are named as courses or 2-point line. A course has only two vertices. The survey measurements that describe the courses can be stored in a traverse file in the context of ArcGIS. From the topography point of view, a traverse is a classical method for a detail topographic survey of an area. In ArcGIS, in a closed traverse, the consecutive lines start from a known point and end at the same or another known point. In an open traverse, the consecutive lines start from a known point and do not end at a known point. By known point or control point, we mean a fixed (ground) point of known X and Y coordinates.

With the Create COGO Fields, Update COGO Attributes, and Construct 2-Point Line tools from the COGO toolbar, you can add, calculate, and update the COGO attributes for an existing feature class.

Note

For theory and worked examples about azimuth, bearings, horizontal distances, types of curves, and simple two-dimensional traverse computation, please refer to:

Principles of Geospatial Surveying, Artur L.Allan, Whittles Publishing, 2007, Technical Procedures, pp.7-18, Survey Computations, pp.145-150, and Construction and Curves, pp.240-244.

Getting ready

In this recipe, we will work with the RoadL layer to create new features using the Midpoint tool and to edit the existing features using the Line Intersection and Extent tools. You will add new attribute fields to the RoadL layer using the Create COGO Fields tool in ArcCatalog. Finally, you will update some parcels from the LandUse layer based on the coordinate geometry coming from a computed traverse. You will use a 2D closed-loop traverse. The line segments are described by direction, which is expressed relative to North Azimuth, and by horizontal distance, as shown in the following screenshot:

The curves from your traverse are circular curves with constant radius. In the context of ArcGIS, curves are defined by arc, radius, chord direction, and side (Curve 6) or by arc, radius, and side when you already know the start point and direction for a tangent and don't need to specify the chord direction and tangent (Curve 10). You can calculate the rest of the elements that describe a simple curve, such as Angle, Chord Distance, or Tangent Length, using the Curve Calculator from the COGO toolbar, as shown in the following screenshot:

How to do it...

Follow these steps to update the RoadL layer:

Start ArcMap, and open an existing map document AdvancedEditing.mxd from <drive>:\PacktPublishing\Data\EditingData.
From the Bookmarks menu, select Create Field road. In the Table Of Contents section, right-click on the RoadL layer, and navigate to Edit Features | Start Editing. Add the Advanced Editing and COGO toolbars. In the Create Feature window, select the Field road template. In the Snapping toolbar, select only Vertex and Edge Snapping. In the Editor toolbar, select the Midpoint tool to create a centerline based on the Transportation subtype from LandUse, as shown in the following screenshot:
Click on point (1), and then click on point (2), to add the first vertex of the sketch at the midpoint between point (1) and point (2). To add another vertex, click on points (3) and (4). Those points are on the edge of the LandUse polygon. Continue to add vertices to the end of the road.
To connect Field road with Rural road (point (5)), and to split Rural road at the intersection, let's use the Line Intersection tool from the Advanced Editing toolbar. Select Field road and the Line Intersection tool. First, click on the end of the selected feature (red circle from the preceding screenshot), and secondly click on point (5). Press O to choose the Extend existing feature option, and click on OK. Finally, click again on point (5). Click on Undo Line intersection to undo the last action.
You will test another way to split Rural road and to correct undershoots. First, to specify the feature that you want to connect to, select the Rural road. Secondly, select the Extent tool. Finally, click on Field road to specify what vector you want to extend to Rural road (red circle from the preceding screenshot). To split Rural road at the intersection, select the Split tool from the Edit toolbar, and click on point (5).
Save and stop the edit session. Save the map document at ...\Data\EditingData as MyAdvancedEditing.mxd.
Let's add new features to the RoadL layer using COGO:
Open ArcCatalog. Click on the drop-down arrow from the right-hand side of the Standard toolbar, and navigate to Customize | Commands. In Show commands containing, type cogo. Select the Create COGO Fields tool, drag-and-drop it on the Standard toolbar. Select the RoadL feature class, and click on the Create COGO Fields tool to add the specific COGO fields. Close ArcCatalog, and open MyAdvancedEditing.mxd.
It's time to specify the angular units. In the Editor toolbar, navigate to Editor | Options | Units. In the Angular Units section, choose North Azimuth for Direction Type and Gons for Direction Units. In Display angles using, type 4 for decimal places. Click on OK.
Start an edit session. In the Table Of Contents section, right-click on the RoadL layer, and select Open Attribute Table. Inspect the COGO fields that were created. Leave the Table window open.
We will transform polyline 1 and polyline 2 into COGO lines and add a new 2-Point Line as shown in the following screenshot:
Let's consider polyline 1 coming from an old survey taken in the field and polyline 3 coming from screen digitizing. To differentiate those two polylines, we will transform polyline 1 into COGO lines. Select polyline 1, and click on the Split into COGO lines tool from the COGO toolbar. Click on Template, choose Field road as the feature template, and click on OK. To calculate the coordinate geometry for the newly created lines, select the Update COGO Attributes tool. Inspect the changes in the Table window.
Let's add a COGO curve starting from point (1) as shown in the preceding screenshot. From the Bookmarks menu, select Create a COGO curve, then select Construct 2-Point Line, and finally select polyline 2. The black arrows indicate the direction of the vector. Choose the curve with the Chord field of 100 meters, the Angle field of 482 gons, the Chord Direction field of 285 gons, and the Turn field of Right to obtain a curve. In the Reference section, navigate to Use selected line | Start Point. Click on Create to obtain Case 1. We expected to obtain a curve from point (1), but the line started from polyline 3.
Select the Edit Vertices option from the Edit tool to see the direction of the vector. The red vertex indicates the end of the vector. To reverse the direction, right-click on the selected vector, and choose Flip.
Repeat step 7 to obtain Case 2. Click on Create and close the window.
To calculate the coordinate geometry for the newly created curve, select the Update COGO Attributes tool, inspect the changes in the Table window, and save the edits.
Let's update a LandUse parcel using the Traverse tool:
From the Bookmarks menu, return to Create Field road. In the Table Of Contents section, check the LandUse layer to see the feature templates in the Create Feature window. In the List by Selection mode, set only the LandUse layer as the selectable layer and return to the List by Source mode. Select the parcel as shown in the following screenshot:
We will replace the existing parcel with a new one using the survey recently taken in the field. We will consider that traverse from the Parcel_Owner1.txt file was already adjusted for a closure error. Select the Replace Geometry Tool option from the Advanced Editing toolbar. Select the Traverse tool from the COGO toolbar. Right-click on the Traverse window, and select Load Traverse. Go to ...\Data\EditingData, and select the Parcel_Owner1.txt file. Click on Finish, and close the window.
Examine the spatial errors. Notice there are some overlaps and gaps between the parcels. Let's try to correct some errors. Select the Align To Shape tool from the Advanced Editing toolbar. Follow the options and steps from the following screenshot:
With the trace tool, start from the first point (Start buffer), and define a short segment on the edge of the updated parcel. To finish the trace and return to the Align To Shape window, double-click on the last point (Finish buffer). Try to change the value of Tolerance to see how the buffer changes. Next, click on Align to modify the edges of the neighboring parcels. Then, continue to align the parcel by updating the Tolerance value. Finally, click on Close to close the window. Inspect the attributes of the new parcel. The attributes remain unchanged because of the Replace Geometry Tool option.
Save the edits, and stop the edit session. Save the map document to ...\Data\EditingData as MyAdvancedEditing.mxd.

You can find the final results at <drive>:\PacktPublishing\Data\EditingData\MyEditingResults.

How it works...

Regarding step 3, it is not necessary to have an existing feature to define the line segment. We just indicate the two points directly on the orthophoto map.

To store the COGO in the attribute table of the RoadL layer, we created empty COGO fields in ArcCatalog with the Create COGO Fields tool. By adding a COGO curve, we have emphasized the importance of digitized direction.

We used the Replace Geometry Tool option from the Advanced Editing toolbar in order to keep the attributes of the LandUse parcel and its relationship with the Owner table.

After we updated the parcel at step 11, we corrected the edges of the neighboring parcels in order to maintain the adjacency between the surrounding parcels. Using the Align To Shape tool is a right decision because we assumed that horizontal positions and dimensions of the new parcel are more accurate than manual digitized parcels.