Introduction
Some Unmanned Lidar System (ULS) datasets can be very large. When projects become too large to be processed in one file (>500m points), it may become necessary to create a TerraScan project, which splits the lidar dataset into smaller, easily processed blocks, based either on an automatically created grid or manually created polygons. Unfortunately, the Wizard ↓ Process Drone Data… tool will not process a project that has been split up into blocks. This workflow will cover the manual steps necessary to create a TerraScan project from ULS data without relying on the Wizard to complete the entire process.
Data Input requirements
- Lidar strips/lidar import file
- Trajectory files
- MicroStation or Spatix seed file
Software requirements
- Spatix or Microstation
- TerraScan
- TerraMatch
Spatix and Terrasolid products can be downloaded at Terrasolid.com.
Disclaimer: Results will vary based on your data. These are generalized settings recommendations and are not guaranteed to work on all datasets. You will need to modify some settings and macros to suit your data.
Note: drop down menus are indicated in bold italics. A down arrow (↓) represents selecting a sub menu in a dropdown menu.
Workflow
- Run Import Wizard for project
- View Trajectories
- Run Split Trajectory Macro
- Tile/Create Project
- Deduce using time
- Define Tie Lines
- Search Tie Line Tool
- Find Tie Line Matches
- Run the rest of the Wizard steps (50sf Neighbors)
Run the Drone Wizard Import and Split Trajectory
In the TerraScan main dialog, select Wizard ↓ New Drone Project… Load in all DJI Terra .las files and sbet files
- Click OK
- Select Wizard ↓ Process Drone Data…
Select only the Split Trajectory step and run it by clicking OK
- Save raw point cloud
- In the TerraScan main dialog select File ↓ Save points
Creating a TerraScan Project with Blocks
This workflow is useful for large projects that need to be broken into smaller chunks to allow multiple users to work on them at the same time.
Note: this workflow only works with the full version of Terrasolid and does not work with TerraScanUAV.
- On the TerraScan main toolbar, long click the Scan Settings button to access the rest of the General tools.
- Select Define Project
- File ↓ New Project…
- Cloud type: Airborne lidar
- Description: *Name of the project*
- First point id: 1
- Storage/Attributes: LAS or Fast Binary (or preferred format)
- Attributes…
- Select all available
- Set Color to 3*8
- Set Time to GPS standard time
- Attributes…
- Data in:
- Project file directory: Will look for saved lidar files in the same folder where the TerraScan .prj file is saved
- Separate directory: *desired save location within project folder* Will look for saved lidar files in a specified directory, separate rom the .prj file save location
- Project file directory: Will look for saved lidar files in the same folder where the TerraScan .prj file is saved
- Load class list automatically: *Use if you want to automatically load a specified/custom TerraScan .ptc file*
- CHECK: Load trajectories automatically: *Browse to the folder containing the TerraScan trajectory file(s)*
- Default block values: Set your preferred Neighbor area type, Block size, Group count, Block prefix for file naming, and Block naming type (number after prefix in file name)
- Click Ok
- File ↓ Save project As… The project must be saved before points can be imported
- Cloud type: Airborne lidar
- In the Project dialog, File ↓ Import points into project…
- Browse to your existing lidar file(s), select them, and click Open
- TerraScan will read the file Format: automatically if it is a standard format. You are able to assign Input projection: info if that is available and necessary. You can also Transform: your points at this point, as well as specify the Input time: format. In the Storing points section, select Create grid blocks and No overlap. Leave the checkboxes unchecked, with the exception of the Autosave project after import. There are a variety of options available to use to assign Line numbers and Scanner numbers.
- Click OK, and the point import process will begin. TerraScan will start creating blocks in the directory, file format, and naming convention specified in step 3 when the .prj file settings were specified. The import can be time consuming based on the size and number of files being imported. Please be patient as TerraScan imports the project points. Once the import is complete, you will see the names of all of the blocks/lidar files created during the import process in the Project dialog.
- The next step will draw vector graphics and text representing the project blocks into your MicroStation .dgn file. The block graphics will be drawn on the active level, color, weight and style. The labels will use the current Place Text Style settings for font, justification,height, width, etc. Change these settings before drawing the blocks into your .dgn
- In the Project dialog: Blocks ↓ Draw boundaries…
- Draw: All blocks
- Label: Unique end of name
- In the Project dialog: Blocks ↓ Draw boundaries…
In the Project dialog, select File ↓ Save project
Define Tie Lines
- In the TerraMatch toolbar: Define Tie Lines
- Input settings appropriate to your data
- Verify Trajectory dir: is pointing to the correct folder
- Click OK
- This launches the Tie Line dialog
Search Tie Line Tool
- In the Tie Line dialog: File ↓ Search tie lines…
- Use: Project points
- Laser project: Browse > select project file (.prj) saved previously when generating the project
- Find planar points: Checked
- Spacing: 2-5 sf
- Radius: 1 sf
- Max slope: 60 deg
- Tolerance: 0.200 sf from plane
- Max angle: 3 deg from average
- OK
- TerraMatch will search for tie lines
- After loading, tie line positions will populate in the Tie Line window
- Tie Lines window: File > save as..
- *save out tie lines
Find Tie Line Matches
- TerraMatch toolbar: Find Tie Line Match
- Find Tie Line Match window (run this process twice)
- First run the process on Heading, Roll, Pitch:
- System: Airborne
- Source: Active tie lines
- Trajectory dir: verify same split trajectory files from project
- Solve for: Line Groups
- Scanners: Combined solution
- Correct: All solution sets
- Check:
- Heading, Roll, Pitch shift
- OK
- View outputs:
- Repeat process with a Z Shift:
- System: Airborne
- Source: Active tie lines
- Trajectory dir: verify same split trajectory files from project
- Solve for: Line Groups
- Scanners: Combined solution
- Correct: All solution sets
- Check:
- Z shift
- OK
- View outputs:
- First run the process on Heading, Roll, Pitch:
- Close Tie Line window
Run the rest of the Wizard steps
Run the final parts of the TerraScan Wizard to classify the point cloud
- TerraScan points window: Wizard > Create Drone Macro
- Select all steps except split trajectories and match passes
- OK
- In the Macro window: File > Save as > “Finalize_Wizard”
- Project window: Tools > Run macro…
- Run Macros on Block window: Add > “Finalize_Wizard” macro
- Process: All Blocks
- Neighbors: 50 sf
- Save Points: Write over original
- OK to run the macro
- Once complete, assess the quality of the classification and continue on with calibrating and cleaning the dataset
