How to transform point cloud file from one UCS to another in Autodesk RCP and Leica PTS formats

Hi @dchar,

FME currently has no dedicated reader or writer for the Leica PTS format. However, it is a simple Ascii file that can be read with FME's Point Cloud XYZ reader. Writing is a bit more complex, requiring an FME Workbench workspace to insert the first record containing the number of points.

FME can currently only write to Autodesk Recap RCP and RCS files.

FME Workbench has a number of tools that can be used to convert between world, projected and user coordinate systems, including the Reprojector, Scaler, 3DRotator, and 3dAffiner transformers.

If you would like to provide more details on your desired transformation, I would be happy to create an annotated workspace to illustrate how to do it in FME.

Hi @dchar,

The Point Cloud XYZ reader parameters has a Lines to Skip section, where you can set the number of lines to skip to 1 to avoid reading the number of records.

To test whether the point cloud has RGB values on it, use a PointCloudFilter to test if the component color_red == -1. If the point cloud has no RGB, it will be output through the <Rejected> port. If it does have RGB, it will be output through the Unfiltered port.

Hi Dave - can you explain why the precision of the output point cloud is so much higher than the input file? I would like to be able to maintain the same number of decimal places in the resulting point cloud. I am assuming that this has something to do with the data type (real64) in the reader or writer. The other issue with the larger values being output is the amount of time it takes to write the transformed file. It took 1.5 hours to transform a 55MB pts file to translated pts and rcp. Once again, any advice you could provide would be appreciated.

Also, you mentioned inserting the first record containing number of points. How would I go about either maintaining this record or rewriting it to the output file?

Hi @dchar,

When calculating the result of the transformation, FME will use the number of decimal places allowed by the data type of the components. However, you can use the @floor or @ceil functions in the PointCloudExpressionEvaluator to round off the subsequent coordinates before writing to the output.

I am attaching a workspace that uses the Text File reader to read the header record (by limiting the number of lines to read) and the Point Cloud XYZ reader to read the point values. The header record is sent to a Text File writer, and the transformed points are sent to a Point Cloud XYZ writer set to append to a file.

By ordering the writers in the Navigation window of Workbench, we can control which writes first. In this case I have the Text file writing first, then the Point Cloud XYZ writer appending to the same file. FME will completely write to the first writer before it starts to write to the second, so collisions are avoided.

The workspace does a simple rotation to simulate the transform, then rounds the point values with the PointCloudExpressionEvaluator. You can replace the Rotator with your own transformation logic. The workspace runs in about 5 seconds on a 800,000 point PTS file.

transformpts.fmw