For comparing multiple datasets in a single profile view in the exact same location, all of the Point Source IDs will need to be edited and combined into one LAS layer on import.
Before bringing this exercise, import all the desired datasets into a single project, then copy the LAS layers (right-click the layer, selected Copy LAS Layer, set output location and change the name of the LAS to the corresponding date or just name then flight1, flight2, etc.) The purpose for performing this task is to make a copy of your data so that the existing LAS file doesn’t get edited or mislabeled in the following steps. The steps for doing this are below.
Preparing your data:
1.) To begin this exercise, load in the LAS files for each dataset you would like to work with individually into LP360 using the Add Files dialog on the Project ribbon. You would do this after the datasets have already been processed. See the Add Files Dialog screenshot below.
- Ensure that all LAS layers are in the same coordinate system.
- To prevent confusion about each layer, right click on the LAS Layer you just imported into LP360 in the Table of Contents, then click Rename. Name the layer something meaningful so you can identify it layer. Example:
- Repeat for all of the datasets you would like to work with.
2.) Optional: If you have a dataset that is tiled LAS files, you can merge them into a single LAS by right-clicking on the newly imported, renamed LAS layers and select Create LPLAS Layer>Single LPLAS file
3.) Right-click on one of newly merged, renamed LAS layers and select Copy LAS Layer…
- Set the New Destination of your LAS Layer and provide a meaningful name.
- The Destination location will be based on the Default Project Root Folder you’ve set. If you have trouble finding the copied LAS, right-click and select Open Location in Explorer.
- Be sure the settings for the LAS files are set to Copy LAS Files and Permissions to Read-Write
- Click OK
Repeat for all of the desired datasets.
Once the copies have been created, it is time to change the Point Source IDs.
4.) Open the LAS File Analyst dialog by right-clicking on the desired LAS Layer and selecting LAS File Analyst
5.) Highlight all of the LAS files in the LAS File Analyst Dialog. Make sure all LAS files stay selected.
6.) Once this is complete, click the Display LAS File Analyst Options Dialog button. See screenshot below.
- Navigate to the Edit Tab
- Click the checkbox next to Set Point Source ID
- For your first flight, set the Absolute value to 1
- Click Apply, then OK
7.) Press the Edit button to execute the change.
Repeat steps 4-7 for all of your datasets. You can check where the files were output to by right-clicking on the copied layer and select Open File Location. For each flight, set the Absolute value to the corresponding number. Example: Flight 1 = 1; Flight 2 = 2; etc.
Once this is done, you will save and close the current Project and create a new Project.
1.) This time, we are going to load all the new copied LAS files from each dataset into LP360 at once to create a single LAS Layer in the new Project. In the Add Files dialog, navigate to the first copied LAS and click Open. Repeat with each copied LAS until they all appear in the dialog. Then click OK.
Now you will see all the LAS files have been loaded into a single LAS layer in the table of contents in LP360.
2.) Open the Live View Filter, click Scan/Refresh in the top right of the dialog, then navigate to the Point Source ID tab.
- Along the right-hand side of the dialog, select Filter Only
- You can then toggle each flight on and off
- If there are additional point source ID options outside of the ones you set (Flight1-1; Flight2-2; etc.), uncheck the extra IDs so only the ones you want will be viewed.
- Some point source IDs can be stored from the original LAS files, this step will prevent them causing display confusion.
- You can also change the symbology colors of each of the IDs to have a discrete contrast between Flights in the Profile View
3.) Draw a Profile Line wherever you desire to compare the datasets.
4.) Once the Profile Window appears, change the Display to Point Source ID (See figure below).
5.) Select the dropdown next to the Drape Options button in the Profile View window and select Drape Profile by Point Source ID. (See figure below). You should notice that the drape line colors correspond with the symbology you set for your Flights (Point Source IDs) in the Live View Filter.
Note: You can turn off the point cloud and view only the drape lines by simply clicking on the Display option button. This will turn off the point cloud display in the Profile View window. The Display button will no longer appear blue is deactivated.
6.) Next, click the Profile Export Settings button directly next to the Drape tool. Set the output location for a shapefile we will create in the next step.
7.) Click the Export Drape Line to File button to create a shapefile from the drape lines.
8.) Now open the Add Files dialog, select the Feature as the import type, and add your new shapefile to the project. NOTE: The output can be automatically added to the Map View, but not always.
9.) Now right-click the feature layer and select Feature Analyst to open the dialog.
10.) Click the Feature Analyst Options button and navigate to the Analysis tab, then the Vertical sub-tab.
- From here, you can select which statistics you would like to see for this given feature (Min/ Max Slope, etc.)
- Select all features in your shapefile, then click the Analyze all features based on tests selected in the Feature Analyst Options Dialog button (window icon with a green check mark). This will execute the analysis you selected.
- Each feature corresponds to each of your Flights.
- You can analyze the Slope between vertices in the Feature Analyst dialog along with identify the X and Y values of each vertex in the new shapefile.
- Select ONE feature in the shapefile, then click the Vertices tab to analyze.