Smoothing Linework June 2012, Planetary Mappers Meeting

Smoothing Contacts What is smoothing: Smoothing allows you to add curvature to linework making it arcuate instead of straight between vertices Why you should smooth: Smoothing enhances the look of the map, eliminates jaggedness, and can help with triple junction relationships

Smoothing Contacts How does ArcMap smooth lines: There are 3 ways to smooth lines in ArcGIS: Manual Bezier Interpolation with offset parameter PAEK - Polynomial Approximation with Exponential Kernel with tolerance Bezier Interpolation with no input parameters Manual Smoothing: This feature allows the user to operate within the ArcMap program, select a feature(s), set the maximum allowable offset, and smooth the line(s) This method uses the Bezier interpolation method Pros: Allows smoothing on the fly Cons: Does not respect snapping Lines can be wildly offset in some locations

Smoothing Contacts PAEK v. Bezier Interpolation: PAEK - asks for a smoothing tolerance, uses it as a length between new vertices along the curve. Does not pass through existing vertices Higher tolerance = higher length between vertices = less preserved detail Lower tolerance = less length between vertices = more preserved detail Allows you to preserve the location of endpoints Bezier Interpolation – use a subset of the existing vertices to fit curves Same method as the manual version Except there is no offset specified Offsets increase between vertices Less original detail is preserved Does not preserve endpoint locations

Smoothing Contacts Using the Smooth Line Tool: Located in the ArcToolbox menu in ArcMap Under Cartography Tools In Generalization Double click to open the Smooth Line dialog box

Smoothing Contacts Using the Smooth Line Tool: Add your Input Features from the dropdown list, drag and drop from the Table of Contents or add from a folder Specify the save location and name of the Output Feature Class Choose a Smoothing Algorithm – PAEK or Bezier Interpolation If using PAEK: Set Smoothing Tolerance Preserve Endpoint If using Bezier: Tolerance and Preserve Endpoints will be unavailable

Smoothing Contacts Using the Smooth Line Tool: Handling Topological Errors option Allows user to flag errors created by the smoothing process Creates a binary column in the table and flags errors Can be helpful & doesn’t increase processing time, but we don’t typically use it We will introduce an alternative, more specific method for finding errors associated with smoothing your linework in the next section

Smoothing Contacts Summary: 3 ways to smooth your linework Manual Bezier with offset, available on the Advanced Editor Toolbar PAEK with tolerance and Bezier Interpolation in Arctoolbox For contacts, we recommend using PAEK because: It preserves endpoints You took the time to snap your contacts, you want to preserve that work You have the ability to tweak the tolerance and the curvature TIP: Always keep the unsmoothed version of the contacts You’ll need this to edit the contacts after the reviews come back We do not recommend editing smoothed linework You will have straight line segment where you edit

Smoothing Contacts Hands-on Demonstration

Topology

What is topology: Topology is the arrangement of how point, line, and polygon features share geometry. Topology is employed to do the following: Constrain how features share geometry. For example, adjacent polygons such as geologic units have shared edges, and contacts have shared nodes and snapping relationships. Define and enforce data integrity rules: e.g., no gaps should exist between geologic units, there should be no overlapping or intersecting lines, etc. Support topological relationship queries and navigation, such as to identify feature adjacency and connectivity. How do we typically use topology We look at snapping, overlapping and intersecting relationships of the contacts at major phases during the construction of a geologic map Anytime before we build geologic polygons After running a smoothing algorithm

Topology Creating Topology Open ArcCatalog Navigate to your.gdb In the Contents window Right click a blank area Select New from the popup Select Topology A new window will open

Topology Creating Topology Press Next to continue

Topology Creating Topology Add a memorable name Use the name of the feature class Also use the word topology e.g., Contact_Topology A note about cluster tolerance: Please leave this as the default This is a calculated value You cannot enter a smaller value A larger value will not have a beneficial effect Click Next to continue

Topology Creating Topology Select the feature class(es) Click Next to continue

Topology Creating Topology This screen allows you to set a rank on to determine how far the feature class will move when it is validated In this example we only have one feature class If you have more than one, decide which feature class you are willing to give more freedom of movement Click Next to continue

Topology Creating Topology Adding Rules Click the Add Rule button The Add Rule dialog pop-up: Choose the features Choose the Rule If necessary, choose a 2 nd feature class The rule that is currently selected is both visual and verbally described Check the Show Errors box to display the errors in the visual description Click ok to add another rule, repeat as necessary

Topology Creating Topology Rules for lines Must Not Overlap One feature may not overlap another feature Must Not Intersect One feature must not intersect another feature without a node at the intersection Must not have Dangles All nodes must be snapped to an edge, vertex, or node Must not have Pseudos A line with more that 2 nodes Must Not Self-Overlap One feature cannot overlap itself Must Not Self-Intersect One feature cannot cross itself without a node at the intersection Add all the rules that apply, click OK Click Next to continue

Topology Creating Topology Last screen is a summary of the: Name Tolerances Feature classes and ranks Rules Click Finish to build the Topology When Topology is finished building, a popup will ask if you would like to validate? NO is the correct answer We will do it later, when we can undo it! Click Next to continue

Topology Now you have your very own topology

Topology Display your Topology Add it to your ArcMap project the same way you would any other feature class It will ask if you want to add the feature class associated with the topology If it’s already open in the project click No If it is not, click Yes You say “My topology is in the Table of Contents, but nothing is displayed, is my map perfect?” I say “No” We need to validate the topology (I told you we’d get to it later)

Topology Validate Topology

Topology Validate Topology Start editing the feature class associated with the topology

Topology Validate Topology The topology toolbar becomes active and you can validate from the Validate Topology in the Current Extent Button (Highlighted in blue) Give the computer time to validate It’s checking every line in the feature class, this can a while

Topology Validate Topology

Topology Hands-on Demonstration