Monday, March 28, 2011

Thinning a LAS file with FME 2011

FME Desktop 2011 comes with a bunch of revamped transformers designed to work with point clouds - specifically LiDAR datasets. In previous versions, FME can only read in LiDAR LAS files but I'm thrilled with this new version now since it comes with a LAS file writer.

I tried out the new point cloud transformers by performing one of the standard LiDAR processing production tasks - thinning the data by resampling at every nth point. It is simple to build a transformation workspace to do the job. Here are the steps:
  1. Start up FME Workbench 2011.

  2. Click Blank Workspace.

  3. From the Windows Explorer, drag a LAS file and drop it onto the FME Workbench Main pane.
    The Add Reader dialog box appears.
  4.  Click OK.
  5. Activate the Transformer Gallery tab on the left.
  6. Find and select the PointCloudThinner transformer in the Transformer Gallery tree list. Drag and drop it onto the Main pane.
  7. Select Writers | Add Writer.

    The Add Writer dialog box appears.
  8. Choose the ASPRS Lidar Data Exchange Format (LAS). Browse and select the output dataset.
  9. Click OK. Click Yes and OK to the next few prompts.
  10. Connect the datasets and transformer as shown.
  11. Open up the PointCloudThinner Parameters.

    The PointCloudThinner Parameters dialog box appears.
  12. Choose the Keep Every Nth Point Thinning Type. In the Amount field, type in a value e.g. 10.

  13. Click OK.

  14. Run the translation.

    The LAS file is thinned

1 comment:

Dale said...

Thanks for the mention. Point Cloud datasets a truly an impressive data capture, and I'm glad you've already put FME to use helping you with them. Don't know if you saw http://blog.safe.com/2011/01/how-to-put-lidar-and-point-clouds-in-their-place/ , but in that article I discuss some additional workflows that may be of interest as well.

Thanks again!

Dale

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