Module 5 - Processing Terrain Data

Description

In this module you will learn how to view element that make up a terrain. You will also learn how to edit the terrain, by adding brake lines, void regions and an exterior boundary.

 

Objectives

• To become proficient with the terrain viewing and editing tools and option.

• To become familiar with the CTDOT Standards set up for Terrains.

Quick Steps

Terrain Attribute Descriptions

Step 1 - View Settings: Triangles/Contours

Step 2 - Inspect Contours

Step 3 - Process Terrain Features

Step 4 - Add Break Lines

Step 5 -  Add or Delete Void Regions

Step 6 - Fix Crossing Break Lines

Step 7 - Edit Triangles

Step 8 - Create Outer Boundary

Step 9 - Import Boundary

 

Before attempting to open or create DGN files users should make sure the following is in place:

• CTDOT users should have the CTDOT CONNECT DDE synced through SharePoint with the COMPASS Project Synced along with the CAD Configuration follow Volume 1 - Module 3 - CTDOT Employee DDE Sync.
• Consultants should have one of the following set up: Volume 1 - Module 1 - Consultant DDE Install or Volume 1 - Module 2 - Consultant DDE Sync.
• Set up your Interface follow the steps in Volume 1 - M.6.2 Setting Up the Interface (ct.gov).

Terrain Attribute Descriptions

Not Set

Determine By Feature Definition

Do Not Include

Break Line - Breaks are used to designate linear features such as edges of pavement, ditch bottoms, ridges, etc. where an abrupt change of slope occurs. Any longitudinal element may be defined as a break line. Triangles will not cross a break line in the terrain model.

Soft Break Line - A soft break line is a break line; however, if it crosses a break line, it will not affect the triangulation and is ignored.

Boundary - The external boundary of the surface.

Drape Boundary - A surface boundary that determines its elevations by draping on the underlying surface.

Void - An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. The Void coordinates are included in the triangulation and void lines between successive void coordinates are inserted as drape lines on the surface; therefore, they do not change the slope or elevations of the surface.

Drape Void - An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. In the drape void, the void coordinates are not included in the triangulation. Voids are inserted post triangulation. The void coordinates and lines are draped on the terrain model surface. Even though a user must provide an elevation for Drape Void vertices, the user elevations are changed to the elevation of the terrain model surface at the XY Drape Void coordinate position.

Break Void - An area defined by a closed shape that demarcates a region of missing data or obscure areas. No point or break data located within the void area is utilized and no triangles are created inside the void areas. It differs from Voids and Drape Voids in that it utilizes the vertex elevations of the graphical element, while the void lines between successive void coordinates are inserted as break lines; therefore, break voids change the slope and elevations of the surface.

Island - An area defined by a closed shape that demarcates a region of data wholly within a void. Example, islands in the middle of rivers, lakes, etcetera.

Contour - Element or set of elements of the same elevation. Contours may be used as source data to generate a terrain model or may be computed (drawn based on terrain model). Contour interval is the elevation difference between two adjacent contours.

Hole - An area defined by a closed shape that demarcates a region where the current terrain is ignored, and the underlying terrain is utilized.

Step 1 - View Settings: Triangles/Contours

Breaklines and points can be edited to change their terrain model attributes; however, terrain commands such as deleting triangles will not work until Survey Processing Rules are deactivated.

Contour and triangle appearances are set by a template. To change their appearance to the familiar orange triangles:

1. Select the Boundary element using Element Selection.

2. From the Properties dialog, click Terrain Model: Existing Template.

3. Choose Template> Existing Terrain> Existing Contours and Triangles.

4. CTDOT will add more predefined choices based on District Survey input; however, the contour interval in the active file can be changed. Choose Template> Existing Terrain> Existing Contours and Triangles> Manage Templates.

8. It the default Minor Interval of “5” is not desirable double click the value of “5” and enter “1”

If contours do not appear correct, Choose Existing Terrain> Existing Contours and delete.

 

Step 2 - Inspect Contours

« Top View Hi Spots or Depressions

1. Visually inspect for abnormalities in top view.

 

2. Use the tools at the top of the view window to zoom, fit, and pan.

 

3. Edit features if necessary through Survey Details.

 

« Front View Spikes

1. Visually inspect for vertical abnormalities in front view. Rotate the view using the View Rotation tool.

 

2. Render the view through View Attributes. Try different Display Styles such as Smooth: Modeling or Thematic: Height.

 

3. You can also use isometric views for inspection.

 

Step 3 - Process Terrain Features

« Edit Terrain Model Attributes

Change the Terrain Model Attributes of an existing feature. In this example, we will modify a linear feature since it contains both a line and point elements.

 

1. Use Element Selection to select the linear feature.

   

2. Use the Heads-up tool to click Edit Point Features.

Survey Details now reflects the elements of the selected Linear Feature.

5. Choose the desired property value (in this case, Do Not Include) from the drop-down list and click OK. This changes all Point Features that made up the line, but not the Linear Feature itself.

6. To change the Terrain Model Attribute of the Linear Feature, use the Properties dialog. From Terrain Model Attribute, choose Do Not Include from drop down.

Triangles no longer include the edited Linear Feature.

 

Step 4 - Add Break Lines

« Add newly drawn 3D Linear Feature

1. To include a newly drawn 3D Linear Feature as a Break Line.  Choose Explorer> Survey> All Linear Features

2. Right click to Add Graphic Linear feature.

3. Select the newly drawn line when prompted.

4. Accept it and the re-triangulated view automatically refreshes. 

5. From the model tree, click the newly added line, named Default. This is listed at the bottom of All Linear Features.

6. Change the field code in Survey Details.

 

 

« Delete Break Lines

1. To physically delete an existing linear feature. Select the feature using Element Selection.

2. Select all rows of the feature from Survey Detail to confirm.

3. Right click Delete selected items.

 

Step 5 - Add or Delete Void Regions

To add or delete a void region, or to change the Terrain Model Attribute, follow the same process for Break Lines. What follows the pull-down options is a listing of Terrain Model Attributes and their descriptions.

 

Step 6 - Fix Crossing Break Lines

Crossing break lines can be checked each time individual raw data file are processed. Choose the Report Crossing Features tool.

①Survey> ②Terrain> ③Analysis> ④Reporting

Step 7 - Edit Triangles

In order to edit triangles, etc., the terrain model must be made editable. This is done by deactivating survey processing through the Survey tree - not through the OpenRoads Model tree.

« Deactivate Survey Processing

1. Choose Explorer> Survey> active model (e.g. NAD 83).

2. Right click the active modelto Deactivate Survey Processing Rules.

« Edit Triangle Tools 

1. Use Element Selection to select the Terrain Model.

2. From the ribbon, choose Survey> Terrain> Edit Model, the Edit Terrain Model tools appear.

 

 

3.Edit Terrain Model choices are as follows:

 

It is recommended that when using Delete Triangle By Line, the user delete the outermost segment of the triangle and begin drawing the line from the outside of the perimeter inward.

 

Step 8 - Create Outer Boundary

1. The displayed boundary is not really an exterior boundary - it’s merely a perimeter.  Select the perimeter to highlight and verify it.

 

2. Create a graphic element to represent current triangulation limits. From the Survey workflow, choose Terrain> Boundary Options> Add Boundary.

 

 

• Delete Vertex
• Delete Edge Triangle
• Swap Line
• Insert Vertex
• Move Vertex
• Delete Triangle By Line
• Delete Feature

3. Select the perimeter when prompted to Locate a Terrain Model.

 

 

4. Keep the default Method of Extract Graphic.

 

 

5. Click any blank spot in the view to accept the choice.

 

Step 9 - Import Boundary

1. Add the newly created graphic to the Field Book.  Reactivate Survey Processing Rules, click Yes to confirm.

 

 

2. Right click All Linear Features to Add Graphic Linear Feature.

3. Select the element when prompted Accept it.

• Ensure that Survey Details is open
• Expand All Linear Features
• Scroll to the bottom of the list and click Default

4. Survey Details refreshes with the new linear feature.  The default Terrain Model Attribute is Break Line. Change Break Line to Boundary.

 

5. Rename the Linear Feature if desired.