Chapter 7- Basic editing Digitize new features from a paper map or scanned map. Construct new features from survey descriptions. Map areas or objects based on air photos or satellite imagery. Update features that have changed since they were created, or fix errors. Update or correct attributes of features.

Maintaining logical consistency Logical consistency measures how well features in the data set mimic the relationships of features in the real world. Basic editing is concerned with two aspects of logical consistency. –Make sure that ends and corners meet at a common vertex. –Make sure that adjacent polygons share an identical boundary.

Avoiding dangles A dangle—the two lines fail to connect Correct topology—the horizontal line intersects the vertical one, creating three lines. node Automatically connects features and ensures logical consistency. Two approaches are used. 1.Let the vertex be placed anywhere and correct it afterwards. 2.Ensure that vertex is created in the right location.

Snapping tolerance The snapping tolerance is the minimum distance between two vertices at which they are considered to be identical. If the cursor gets within the tolerance of a vertex, the next mouse click will be snapped to that vertex.

Tolerance units Screen units –User sets the tolerance as the number of pixels on the screen. –Remains consistent regardless of the zoom level. –Easy to work with at all scales Map units –User sets the tolerance in map units (meters, feet, degrees) –Ensures consistent precision at all scales –May become difficult to work with when zoomed far in or far out from normal editing scale

Types of snapping End snapping Edge snapping Vertex snapping ? Snapping tolerance + Point snapping

Snapping for points Make sure that sewer connections fall exactly on the house edge. Ensure that stream gauges fall exactly on the stream. What kind of snapping?

Snapping for lines Make sure that road ends meet at other roads. Ensure that stream segments connect to each other. What kind of snapping?

Snapping for polygons Make sure that parcels corners match. Avoid creating spurious nooks and kinks between polygons. Should have been snapped to existing corner. What kind of snapping?

Adjacent polygons Topological errors between two polygons Coincident boundary between two polygons gap overlap It is important to maintain logical consistency of adjacent polygons. It’s much easier to create than to fix later.

Creating adjacent polygons Two methods –Use special tool to construct adjacent polygon –Create a polygon and then cut it into pieces.

Basic Editing What can you edit? ArcGIS Basic –Shapefiles and geodatabase feature classes –Map topology ArcGIS Standard or Advanced –Geodatabase networks –Geodatabase planar topology Coverages cannot be edited in ArcMap. Convert them to shapefiles or geodatabase feature classes.

Coordinate systems ArcMap can edit across coordinate systems –Editing is performed in the data frame CS –Edited coordinates always saved to source file CS regardless of data frame CS. Enter GPS points using degrees with the data frame set to GCS. UTM Points are saved in meters in the file with the UTM coordinate system.

Editing tips Always have a backup copy Open new map documents for editing and add only the layers you need. Keep number of open files down Try to keep layers in same coordinate system to avoid confusion Save frequently!!!!!

Author’s tip Editing seems to occasionally corrupt map documents. It is recommended to do your editing in documents specifically opened for that purpose, containing the minimal number of files needed. Try not to edit in your gorgeous map layout documents that took days to develop.

The Editor toolbar

Setting snapping

Saving work Save early, save often!!! Stops editing and asks to save any unsaved edits Saves and continues editing

Feature templates Feature templates store all info needed to add a feature to a feature class. They also have different construction tools that can be used to create new features. Created automatically or manually Can have multiple templates for each layer Can also enter values in attribute fields

Adding features Choose template and construction tool Click to enter vertices of a “sketch” Double-click to “finish the sketch.”

The Edit tool Edit tool The Edit tool is used to select features so they can be moved, deleted, or edited. Uses the same techniques as the Select Features tool. Click on feature to select Shift-click to add another feature Drag a box around several features Click on empty space to clear selection Use Clear Selection Select Features Clear Selection

Creating adjacent polygons 1.Select the feature template. 2.Select the Polygon construction tool. 3.Enter the first polygon. 4.Switch to Auto Complete Polygon tool. 5.Construct the second polygon, starting and stopping inside the first. 6.New polygon will use the existing boundary of the old one.

Splitting polygons 1.Use Edit tool to select the feature. 3. Use the Cut Polygons tool to sketch the cutting line. 4. Double-click to finish the line and split the polygons. 2. Click the Cut Polygons tool.

Move a feature 1.Select the feature(s) with the Edit tool. 2.Click and drag feature(s) to new location.

Delete a feature 1. Click the feature(s) with the Edit tool to select it. 2. Press the Delete key on the keyboard.

Edit Vertices 1.Use Edit tool to select the feature.2. Select the Edit Vertices tool. The sketch appears. 3. Click and drag to move vertices. 4. Right-click to open Sketch menu to add or delete vertices. 5. Double-click or Finish Sketch when done.

Rotating features 1. Select feature with the edit tool.2. Click the Rotate tool. 3. Click and drag feature around rotation point. (optional) Click and drag the x to move the rotation point.

Splitting lines 1. Select feature with the edit tool.2. Click the Split tool. 3. Click on the point where the line is to be split.

Editing context menus Vertex menu Sketch menu Right-click on the sketch Right-click off the sketch

The Vertex menu Vertex menu Open the menu by right-clicking somewhere on the Sketch. Click on a segment to insert vertex. Click on a vertex to delete or move it.

The Sketch menu Contains functions for adding the next vertex: in a particular direction, with a particular length, parallel or perpendicular to a feature, at an angle to a feature, at an angle to a sketch segment, at a specific x-y location.

Sketch menu options Enter absolute point Enter change in xy Constrain direction Constrain length

Sketch menu options Deflect from sketch Parallel to feature Deflect from feature Direction and length

Multipart features Multipart features are formed from several simple features that may be disjoint. Right-click and use Finish Part to go to next island. Use Finish Sketch after all the parts are done. Hawaii is seven islands, but a single feature with a single attribute row.

Edit Sketch Properties Vertex menu Use to view and/or edit vertex coordinates.

Sketching tools Control the type of edge connecting the vertices Provide different ways to add the next vertex –Straight segments –Right angles –Midpoints –Curves Straight segment tool is the default. Floating Mini toolbar

Right Angle sketch tool 1. Choose the feature template 2. Select the Right Angle sketch tool 3.Click to enter corners. 4.To enter last corner, right-click and choose Square and Finish.

Arc Segment sketch tool 1. Choose the feature template 2. Select the Arc Segment sketch tool 3.Enter vertices along street. Sections will curve in between. 4. Enter last vertex and double-click to finish the sketch.

Attributes window Useful window for editing the attributes of selected features. Shows the currently selected features Edit the attributes of the highlighted feature Edit the attributes here Right-click item for context menu

Editing attributes 1. Click to flash the feature and see which it is. 2. Edit the field. 1.Click layer name 2. Edit the field. Edit a single featureEdit multiple features

Creating new feature classes Sometimes when editing you need a blank, empty feature class into which you will place all new features. The feature class must be created in the Catalog tab or ArcToolbox before you can start editing it.

Creating new feature classes Need to create three new empty feature classes for the tutorial Edwards geodatabase NAD 1983 Texas State Plane Central

New Feature Class 4. Accept default XY Tolerance and Resolution. 3. Import coordinate system 2. Enter name and feature type. 1. Right-click geodatabase 5. Enter fields as needed.

Ready to edit! New feature classes ready for editing!

Start editing You can only edit in one folder or geodatabase at a time. Select one if this window appears.