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Draping Imagery Textures on Terrain Surfaces

Liz Sanderson
Liz Sanderson
  • Updated

Introduction

Draping can be done for both textures and vector geometries. This example will focus primarily on textures, which can be draped over any solid or surface.

Textures have been used as a representative way of assessing GIS, BIM and other models, so that users can make informed business decisions about their data. 

The act of draping is referred to as overlaying a 2D feature, also referred to as textures, onto a 3D feature. Let’s walk through the workspace provided in  DrapingTextures_Hawaii.zip. In this scenario we have draped a PNG Landsat image of two islands in Hawaii, Lanai and Molokai, over TIN surfaces. The workspace below uses contour data to generate the TIN surfaces for both islands. Then Landsat images are added as textures, covering the TIN surface. The Landsat image now acts as a background for the entire scene.



 

Files

 

World DEM Texture Example

If the workspace above looks a little bit too complex, here are some steps to create a simpler workspace, where we use a global DEM to demonstrate draping textures. You can also download DrapingTextures_World.zip to follow along with the exercise.

1. Add a Microsoft Excel Reader

In a blank workspace, add a Microsoft Excel Reader to the canvas.

  • Format: Microsoft Excel
  • Dataset: WorldDEM.xlsx
  • Parameters: Assign X,Y, and Z as the number type.

Click OK twice to add the reader feature type to the canvas.

 


2. Create Scaled Z Value
Add an ExpressionEvaluator and create a new attribute called _z_scaled using this arithmetic expression: 
(@Value(z)/500.0)
 
 
3. Create Points
Next, the VertexCreator will be used to create point data from the WorldDEM spreadsheet coordinates.
  • X Value: x
  • Y Value: y
  • Z Value: _z_scaled
 

4. Create a Tin Surface
Add a TINGenerator to create a TINSurface. Connect the Output port from the VertexCreator to the Points/Lines input port on the TINGenerator.
  • Surface Tolerance: 1
The surface tolerance parameter determines which input points to add to the surface model as vertices.
 
 
5. Read JPEG
Before we can progress, we have to read the world JPEG into FME. Add a new reader to the canvas.
  • Format: JPEG
  • Dataset: WorldImg.jpg


6. Set Appearance

Add an AppearanceSetter to the canvas. This transformer sets appearance styles onto the front and/or back sides of geometries. Connect the JPEG Reader to the Appearance port, and the TINSurface to the Geometry port. Within the parameters set:

  • Texture Mapping Type: From Top View


7. Write to Adobe 3D PDF
Finally, add writer to the workspace.
  • Format: Adobe 3D PDF
  • Dataset: <destination path>\WorldPDF.pdf
  • Layer Definition: Copy from Reader
  • Parameters:
    • Move to Local Coordinate System: No
 
 
Click OK again, and another window will appear prompting you to select one of the existing Reader feature types since we’re copying the schema definition from the Reader. Select the Excel spreadsheet and click OK. Run your workspace and view your results.

The final results should look similar to the image below: 

 

Data Attribution

Lanai and Molokai island data provided by the Hawaiian Statewide GIS Open Geospatial Data Portal.
The World DEM was provided by the National Oceanic and Atmospheric Administration (NOAA) - National Centers for Environmental Information .  

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