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3D Professional Models

The foundation for stakeout plans can be in various forms, but it is becoming increasingly common for consultants to develop and distribute 3D professional models. IFC is widely used in connection with buildings, while 3D DWG models dominate in connection with road projects. Below we will look at how we can handle these models in Gemini Terrain.

Professional Models for Road Projects

Note

Note that professional models for roads are normally delivered on VIPS. This is described in more detail in a separate section.

DXF/DWG Models

When it comes to DWG files, we have two alternatives. We can import the file to an application layer or we can insert it as an object in the drawing.

Both methods have their strengths and weaknesses.

DWG with "true" coordinates in meters (for example, for 3D DWG files from ViaNova coordination model) can be imported to application layer. If we import DWG files to application layer, we get the geometry but lose all presentation. 3D solid objects are also vectorized to triangle net.

DWG with "True" Coordinates in Meters

The 3D professional models normally contain both volume data and stakeout data in the form of lines and points. For most disciplines, stakeout data is provided in the form of points and lines, but for structures, for example, it is delivered as volume objects and the contractor must extract necessary setting-out data from the volume objects themselves. 3D professional models in DWG format can be imported directly to an application layer.

Procedure

Procedure

  1. Select Create... in vertical list field for application layer
  2. Use template DWG.al_
  3. Change name of gmi-layer as needed and click Create...
  4. Click Import...
  5. Select profile and click Format...
  6. Select DWG (direct) in the list and click OK
  7. Click Add file(s)...
  8. Browse to the file, select it in the list and click Open
  9. Click Import
  10. Click OK

In Gemini Terrain we can use the layer structure in the DWG file directly in the program. This means we can turn off all layers that do not form stakeout basis with the function Show layers....

In other cases, the DWG file is often not prepared for harvesting stakeout data as described above. For example, 3D solid objects in Gemini Terrain become triangle nets. These can be complex triangle nets that make snapping less clear. Gemini Terrain therefore contains functions that can break up the triangle net into objects that are more manageable.

Procedure

  1. Select the triangle net you want to harvest stakeout data for
  2. Select Extract boundary contour from triangle net... on the context menu
  3. Select the polygon for the outer edges extracted from the triangle net in the horizontal list field
  4. Select Explode object... on right mouse button
  5. Select exploded polygon and select Generate point... to calculate the center of gravity

DWG with Local Coordinates

The import functionality for application layer requires, as mentioned, DWG models with map coordinates and unit meters, since we cannot georeference application layer afterwards. In these cases, we must create a CFI that we insert as an object in the drawing.

The solution for such files is to insert them dynamically as objects in the drawing.

Inserting DWG model into drawing

Procedure

  1. Select DWG models in the list for models and right-click
  2. Select Add dynamically...
  3. Click Browse... and browse to the folder where the DWG file is located
  4. Select the file and click Open
  5. Click OK
  6. Move the figure dynamically on the screen and snap the origin of the figure to the desired point in the application layer

Professional Models for Buildings

IFC models are inserted as objects in the drawing:

  • Use Add... if the IFC file is georeferenced.

  • Use Add dynamically... if the IFC model is not georeferenced.

Procedure

  1. Select IFC models in the list for models and right-click
  2. Select Add dynamically...
  3. Click Browse... and browse to the folder where the DWG file is located
  4. Select the file and click Open
  5. Click OK
  6. Move the figure dynamically on the screen and snap the origin of the figure to the desired point in the application layer

Transfer IFC Model to Application Layer

We can transfer geometry from inserted IFC files to application layers.

Procedure

  1. Select the IFC object in the drawing
  2. Turn off layers that are not of interest
  3. Select Copy geometry from command file to clipboard... on the toolbar for Planning, Design and Construction
  4. Check 3D and click OK
  5. Select the application layer and select Paste objects...
  6. Click Yes to include properties

In addition, we also have a special function for snapping surfaces in IFC files. This creates a triangle net for the surface. Use the function Snap surface in IFC model and create as triangle net in application layer... for this.

Template for Stakeout Data

It can be more organized to have a separate application layer for stakeout data. In this layer, we can copy/snap data in IFC model, DWG model or CFI model.

A template Stakeout data.al_ has also been created. This presents points and lines with red color so that we can easily see the stakeout data. If we add point numbers, S_OBJID, to the points, we get this as annotation.

See also example collection for implementation:

Exercise 5.2 - Harvest stakeout data from professional model VA