Introduction:

After the proposed surface DTM has been created, a quick comparison of the 3D model versus the 2D design is recommended. Spot check key design criteria such as lane widths, paved shoulder tapers, and guardrail locations are a few items of many design aspects needed to be verified and matched 2D with 3D. The Geopak DTM "Drape Elements" Tool can be used to search for elements/levels in the 2D file and "drape" them on top of the proposed surface TIN file.

Some project rendering and visualization are also recommended. Merging and clipping existing TIN files to the proposed DTM is accomplished with the Geopak DTM "Clip TIN" Tool. It is a simple process of using the proposed DTM exterior boundary shape to clip out the overlapping existing DTM. Once joined, the proposed and existing surfaces will look seamless.

There are various several View Display Modes that will be able to show the material assigned through the level DGNLIB their actual texture and color. Our recommendation is to use the View Display Mode Illustration. The default View Display Mode Wireframe will not show the assigned material.

The material displayed in the 3D model such as grass, concrete, and metal (guardrail) is automatically set in the levels DGNLIB.

Objective:

1. Drape proposed 2D design file elements on top of the proposed DTM surface using Geopak DTM "Drape Elements" Tool.
2. Clip the existing TIN and merge into the proposed DTM with the Geopak DTM "Clip Tin" Tool.

Dataset:

• 07_Design_Verification_and_Model_Visualization.pdf
• b4809_rdy_cmd.dgn
• b4809_rdy_dsn.dgn
• b4809_rdy_ex_101007.tin
• L.tin

Exercises Summary:

• Exercise 1 - Design Verification
• Exercise 2 - Model Visualization

Exercise 1: Design Verification

• NOTE: The DTM surface created for design verification should have Features turned off. This will eliminate the confusion of having the same feature symbology as the 2D design. Elements such as proposed EOT and paved shoulder are on the same level for 3D DTM and 2D design file.

Step 1.
While in the file b4809_rdy_cmd.dgn, launch the Geopak DTM Tools.

Step 2.
Launch the Drape Elements tool.

• NOTE: In the next step, the 2D design is referenced in the 3D DTM file. After applying the drape elements to the proposed surface, the selected elements are actually copied into the 3D DTM file.

Step 3.
In the Drape Elements dialog box, enter the following settings and then Apply. Close out of the Drape Elements dialog box.

Element DGN: b4809_rdy_dsn.dgn TIN File: L.tin Curvilinear Element As: Line String Elevation Offset: 0.100 Stroke Tolerance Linear: 0.000 Stroke Tolerance Curve: 0.000 Search Criteria - Lv Names: (see NOTE below) Action: Apply then Close (X) NOTE: Search for key design elements/levels such as the proposed EOT, paved shoulder, guardrail, bridge, and approach slaps. Not in this particular exercise, but pavement markings, SBG, and C&G can also be included. Use the Match button to select the level of each element. It also helps to have the 3D view rotated to see the reference 2D file. It is also important to point out that only elements that are within the select TIN coverage area will be draped. For example, the centerline must be partially deleted to be able to drape over the proposed DTM because its original limits are outside the TIN coverage area.

Step 4.
Look for common mistakes like lane width tapers and paved shoulder width throughout the project. Some of these errors can be fixed with the proper usage of parametric constraints and targeting features/graphics.

 

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Exercise 2: Model Visualization

• NOTE 1: Clipping the existing TIN.
• NOTE 2: The Add Exterior Boundary feature will create the shape only if Features is checked on in the Create Surface dialog box.

Step 1.
While in the file b4809_rdy_cmd.dgn, turn on level Prop CMT Corridor Exterior Boundary. This will be used as the clipping shape.

Step 2.
Launch the Geopak DTM [Build] Clip TIN tool.

Step 3.
In the Clip TIN dialog box, enter the following settings. Select the DTM exterior shape first in the DGN file then click on the Select button in the Clip Polygon frame to select the clipping shape. Process the dialog box and the new TIN is created. Close out of the Clip Tin dialog box.

TIN: b4809_rdy_ex_101007.tin Create TIN: b4809_rdy_ex_new.tin Clip: Internal Clip Polygon Selection: Select (DTM exterior shape) Action: Process then Close (X)

Step 4.
Launch the Load DTM Features dialog box.

• NOTE: Loading the existing TIN around the proposed DTM.

Step 5.
Enter the following settings in the Load DTM Features dialog box. Click Load to draw the existing surface around the proposed DTM.

Load File: TIN | b4809_rdy_ex_new.tin Load: Extent Display Only: (unchecked) Graphic Group: (checked) Triangles, Default, 0, 0, 0, ON Action: Load then Close (X)