MAGNET Modeler: Mapping an Aerial Image onto a Surface

This guide explains the steps to drape an geo-referrenced aerial image onto an existing surface coming from a LandXML file to create a virtual surface model in MAGNET Explorer. The model generation happens with the help of MAGNET Modeler inside an AutoCAD Civil 3D 2017 environment.

This guide includes a sample dataset to rebuild this workflow.

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MAGNET Modeler: Mapping an Aerial Image onto a Surface

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Importing the Surface

  • Start AutoCAD Civil 3D
  • Go to Insert / Import / LandXML 

  • Browse the LandXML file

  • Hit Open

  • Hit OK


Depending on the surface style your result may look different

Importing the Aerial Image

  • Go to Raster Tools / Insert & Write / Insert

  • Browse the JPG file

  • Hit Open

  • Hit Next three times

  • Hit Finish


There are several ways to insert a geo-referrenced image into Civil 3D. This is one of them.

Preparing the DWG

  • Draw a closed Polyline around the image corners
  • Make sure the Polyline starts at the lower left corner
  • Make sure the Polyline gets drawn in a counter-clockwise direction
  • Create a new layer called Image Boundary
  • Move the Polyline to this layer

Creating a Reference Surface Rule

  • Click the MAGNET Modeler tab
  • Click Rules
  • Double-click Civil3D
  • In the Civil3D dialog define the Main group, for instance Existing/Terrain
  • Click OK
  • Click on Generate Model


This will create a reference surface layer in the background named "Civil3D_surface_GROUP NAME.SURFACE NAME". A reference surface can be used to translate objects from no elevation to the desired surface elevation.

MAGNET Modeler and MAGNET Explorer work with a lot of different submodels to create a single multi-disciplinary model. To be able to quickly show or hide / highlight / analyze or simulate a submodel, we must have a certain model structure in place. Speaking in MAGNET Modeler and MAGNET Explorer terms, we must create Groups. It makes sense to define the group structure before starting working on the project. It is recommended to differentiate models between Existing and Design in the first place and then create appropriate subgroups in the next step. 

Creating a Material Area Rule

  • Double-click on Material areas
  • Double-click on layer in the Properties window
  • Select the Image Boundary layer
  • Hit OK
  • Double-click on materials
  • Hit Insert New material...
  • Assign a name to the material, for instance Aerial Image
  • Double-click on filename and browse to the JPG
  • Hit OK
  • Hit OK
  • Set automatic_textcoords to fit
  • Double-click on target_layers and choose the reference surface layer
  • Hit OK
  • Assign a group (to enable a clean workflow assign the same name as for the reference surface)
  • Hit Generate and View Model

Generating the Model

  • MAGNET Explorer software will be launched automatically and the model will be displayed