When it comes to LIDAR data processing, the synergy between LIDAR Analyst® and Feature Analyst® offers countless advantages. Using a combination of both software programs is the most effective method of unearthing the information available in LIDAR imagery.
Three-dimensional visualization can be achieved with LIDAR Analyst in a matter of hours, including the bare earth surface, buildings, and trees. Then, additional features of interest, such as roads and shorelines, can be classified with Feature Analyst for inclusion in the 3D model.
Below you will find a combined workflow for using LIDAR Analyst and Feature Analyst to perform basic extractions from LIDAR data. Click here to view the information in a printable format.
You are watching Combined Workflow: Feature Analyst & LIDAR Analyst.
1. Load LIDAR Data:
Use the “Load LIDAR Data” tool on the LIDAR Analyst toolbar to import the first, second, and intensity images into the project.
2. Extract Primary Features:
Use the default parameter settings in LIDAR Analyst to perform bare earth, buildings and tree extractions.
Bare earth extraction removes ground clutter, such as trees, building, cars,
and other above ground objects to obtain the best representation of the surface layer, called the digital terrain model (DTM).
Once the bare earth is identified, buildings are easily recognized by LIDAR Analyst
After you have extracted bare earth and buildings from your LIDAR
images, complete your LIDAR data processing by extracting the trees or forests.
3. Identify Additional Features:
Use Feature Analyst to setup your imagery for accelerated feature extraction (AFE). Feature Analyst is an intelligent software agent (a.k.a. Learner)
that learns feature extraction concepts by example.
The first step in any feature extraction is creating a new feature data set. This
data set will contain your training set for the feature extraction.
4. Create a Training Set:
Using Feature Analyst, first select Create New Feature Class on the Vector Tools menu to create a
new feature class.
Draw a training set that clearly represents your target features and run your extraction pass.
5. Run the Extraction Pass:
The road layer in the above example has returned some false positives: a few gaps and some missing streets. Overall, the results are good for a first pass and can easily be cleaned up in the next two steps.
Convert to Line: Use the “Convert to Line” in Feature Analyst function to transform the road network into linear data. Use the default settings first and if the results are not acceptable try experimenting with the gap jumping, dangles, and intersection settings. Apply smoothing after the desired results have been achieved.
Clean up: Use the Feature Analyst Adjustment Tools to clean up the rest of the roads and to draw in any missed segments.
6. View the Model in 3D:
In order to view your three-dimensional model, use ArcScene, ArcGlobe or a similar map software that is customized for displaying 3D data.
If you are using ArcScene, create a new map and add your data. Right-click your data layer (DEM, for example), and choose Properties. Click on the Base Heights tab and select the file path for your bare earth surface data in the "Obtain heights for layer from surface" space. Continue to select your bare earth layer in the Base Heights tab for each of your additional data layers (buildings, roads, etc.) and all of the layers will share the same base elevation and display proportionally-correct height. Below is a three-dimensional fly-through animation.
