Welcome back for another Scanning Tip of the Week for Trimble® RealWorks™ software. This time we will explore a workflow to export clean point clouds by editing the TZF files collected in the field. This method will permanently remove unwanted points so downstream operations will never need to deal with them.
The first step is to import your project into Trimble RealWorks. The Import command in the Home tab is my recommended method but you can also drag and drop your files into the model space. Using the Import command will prompt you to select sampled scans whereas dragging and dropping will require you to select your imported scans and use the Create Sampled Scans tool. Regardless of your choice, make sure you import all points by using the Sampling by Step option with an input of 1. The reason for selecting this option is that TZF editing can only be applied to points present in the project. Unsampled points will not be visible in your project and therefore cannot be selected for removal.
With your project imported and sampled scans created, perform any registration operations you require. For the project used in this demonstration, I used the Cloud-Based Registration tool to adjust some misaligned scans, then used the Refine Registration using Scans tool to finalize my registration.
At this point I recommend using the TZF Transformation tool to Export Station Registration Parameters to TZF Files. This step writes your registration parameters directly to the TZF files, ensuring any future operations will maintain the same alignments.
This concludes the steps in the Registration mode for our project and we can now switch to the Production mode using the dropdown menu above the toolbar ribbon. To keep track of my point cloud editing going forward, I like to create two Group folders to separate my clean point cloud segments and the points I wish to remove. In this case, I named them Clean and Delete. Organizing the unwanted points is especially important for subsequent operations in this example.
To ensure I do not miss any artifacts outside of my area of interest, I use the Segmentation tool to define my wanted points and select Out when creating my initial segments. First I perform this step from a Top View, then one of the side views, such as the Front View.
Next, I like to segment my project into sections for more detailed point cloud cleaning.
At this point, no points remain in my Project Cloud ensuring I did not miss any random artifacts which would show up after exportation. Now I can continue my point cloud cleaning with each segment I created. I recommend moving your unwanted points to the Delete group as you clean by dragging the segmented point cloud object to the folder in the lower WorkSpace window.
After completing all your point clean segmentation edits, you should have all unwanted points located within the Delete folder. Select the Delete folder to highlight it, then go to the Edit section of the toolbar ribbon. Click on the Remove Points from TZF Scans tool within the TZF Scan ribbon area to edit your TZF files.
A warning will appear recommending that you create a backup copy of your original project files as this step is permanent. With your copy created, click Ok to continue. A second warning will appear giving you the option to Compress TZF Scans. Compressing your TZF scans will slightly reduce the exported TZF files sizes but will add time to the export process. A small scale test was conducted to showcase the file size and export time differences for two identical exports.
Make your selection and click Ok again
After RealWorks has finished processing your TZF edits, you will notice nothing changed within your project. The .rwp file still contains all original points from the initial import command. The TZF files found within the .rwi folder contain the edits you have just performed. You now have a number of options based on your needs. The first is to continue with your current project knowing that any future exports will be generated from the clean TZF files you have created. You may also delete all scans from your project and re-extract from the clean TZF files. To do this, use the Find tool in the Search section of the Home tab. Use the Type drop down menu and select Cloud. All scans within the project will be shown in the window and can be selected and deleted. A previous Tip of the Week can be viewed here for further information on using the Find tool.
Another option is to export your TZF files to another file format, such as .e57. To do this, move back to the Registration mode and select all scan files within the lower WorkSpace window. Click on the Export tool within the Home section of the toolbar ribbon. Select the Convert TZF Scans of Selected Stations (Gridded E57/PTX/PTS/RCP).
A window will appear to allow output file selection, export pathing, sampling options, and filtering options. Make the selections you prefer and click Ok.
Once this process is complete, the formatted files will be generated containing the registration parameters and segmentation edits you performed.
Hopefully this Scanning Tip of the Week will assist you in your current and future projects. As always, keep on scanning.
Learn more: Trimble RealWorks Software