An Introduction to Using Lidar with ArcGIS and 3D Analyst
Jim Michel
February 24–25, 2016 | Washington, DC
FedGIS Conference
Outline• Lidar Intro• Lidar Management
• Las files• Laz, zlas, conversion tools• Las Dataset
• Las Dataset Analysis• Profile• Measurement, classification
• Creating Elevation datasets• DSM and DTM with Mosaic Dataset
• 3d Web Scenes in Arcgis• Create 3d web scene
LiDAR
Light Detection And Ranging
Optical remote sensing technology that measures the distance from the sensor to a target
Lidar Data
First Return
SecondReturn
ThirdReturn
Last Return
Lidar Data
First Return
SecondReturn
ThirdReturn
Last Return
DSM
Lidar Data
First Return
SecondReturn
ThirdReturn
Last Return
DSM
DTM
Key Lidar Functionality
• Surface analysis- First-return- Bare-earth
• Feature extraction- Digitizing- Point classification
• Background information- Measuring- Data validation
• Sharing- Serving- Zip-and-ship
3D map
2d GIS Layers
LiDAR
Imagery
DTM DSM
NDSM
Imagery Application
See the forest AND the trees
Natural Resource Management - Forestry
Slope Map
Canopy Height Map
• View, measure
or analyze
from any location
Profile Perspective
Energy – Transmission Lines
Challenges of Working with Lidar Data
• Huge Volumes
• Multiple Sources
• Multiple Projections
• Varying Accuracy
• Multiple Representations
• How to manage?
• How to analyze?
• How to access?
Use of elevation data has been a challenge
Three Data types | Integrates LiDAR across all GIS functionality
Using LiDAR in ArcGIS Provides an open and productive platform for LAS files
• Converts LAS to TIN
• Access to 3D Analyst
• Best Terrain Representation
• Scalable and Seamless
Terrain Dataset Mosaic Dataset
• Used to catalog & serve LAS
• Both LAS & Terrain Datasets
• Store with other DEM
• Use to Orthorectify
Fast access; no conversion
Direct Edit of LiDAR Points
Use with LAS 3D View
Use with LAS Profile View
LAS Dataset
LAS File
• ASPRS Standard• Points and
Metadata• No Indexing• Very Large Files
Esri Optimized zLAS
• Compressed• Lossless• Use Direct• Built for Server
LAS Dataset
• References Multiple LAS, zLAS files
• Surface Constraints• Enables
Visualization
Mosaic Dataset
• Data Model for Serving
• Manages point clouds like imagery
• Generates Surface
Managing LAS Files
Compressed LAS files• Zlas optimized Las files
- Highly CompressedEsri’s compression technology reduces file size significantly more than generic compressors can (e.g., gzip) because it was written specifically for LAS. Better compression results in reduced storage and bandwidth requirements.
- LosslessThe lidar point record data is preserved exactly. There is no loss of information so the full integrity of the data is maintained.
- Directly UsableThe optimized LAS data can be used directly without need to decompress it first. The ArcGIS 10.3 platform has been enhanced to support optimized LAS.
- Efficient Data AccessStatistics and spatial indexing are added during the compression process. This makes the resulting files easier to use and the data is accessed more efficiently for both spatial and thematic queries. An option to sort point records to improve the I/O efficiency of queries on the optimized files is included.
- Free
Las and 3D Sample tools
Demo
•Las formats and tool overviews
LAS Dataset
• New data type• File based • Stores references to LAS files on disk• Optionally reference breakline data• Treats a collection of LAS files as one logical dataset
LAS Dataset Strengths
• Scalability- Works directly on LAS files
• Data Integration- Point cloud and breakline support- Storage efficient
• Data Management- I/O efficient- Edit LAS classifications
LAS Dataset – Creation
• Interactively via Catalog- File folder context menu
• Using scripts and models withgeoprocessing tools
LAS Dataset Editing Class Codes
• Manual- Fixing data anomalies and misclassifications viapoint profile window
• Automated (GP tools)- Classify relative to feature data- Reclassify to standard LAS specification
LAS DatasetInteractive Editing
LAS Dataset – ManageBatch Oriented Editing
• Change LAS Class Codes tool- Set class by proximity to feature data
• Set LAS Class Codes Using Features- Reclassify old class to new class
LAS Dataset – Dataset based LAS Dataset Properties: LAS Dataset Statistics
LAS Dataset – File based LAS Dataset Properties: LAS File Statistics
LAS Dataset – Analysis
• Derive surfaces- As raster- As TIN
• Direct surface analysis- Interpolate shape- Add surface information- Line of sight- Skyline- Locate outliers
• Rasterize on point metrics- LAS point statistics as a surface
LAS Dataset – Point display
LAS Dataset – Surface Display
LAS Dataset – Point Filters
LAS Dataset – 3D Display in ArcScene
Data courtesy Merrick & Co.
LAS Dataset – LAS File Extents
Best Practices
• Tiled LAS, v1.1 or higher• 1-2 million points per file• Projected• Keep file I/O local, avoid network• Airborne
- Classified (bare earth, non-ground)- Breaklines for hydro enforcement- Study area boundary included as constraint
• Terrestrial- RGB, intensity, or classified
Licensing
• Standard, 3D, or Spatial Analyst Extension- Create LAS dataset- Modify LAS dataset schema- Include in Mosaic dataset
- Publishing requires Image extension for Server- View in 2D- Rasterize
• 3D Analyst Extension- Edit class codes- View in 3D- TIN based surface analysis
Demo
Working with LAS Datasets
Distinguishing Concepts• Image Services
- Access to original data- Optimizes System Resources
• On-The-Fly Processing- Process Imagery as Accessed- Create Multiple Products direct from Source
• Dynamic Mosaicking- Fuse Imagery from Multiple Sources- User Defined Ordering
t1t2
t3t4
t5
Mosaic Datasets for Elevation
Mosaic Datasets are a Data Model for Imagery
• Managed Content- Catalogs of Imagery and rasters- Multiple image types / resolutions- Smart use of metadata- Optimized pyramid layers, footprints and thumbnails
• Associates Knowledge with Imagery- Custom raster functions on-the-fly- Dynamic mosaic rules for overlap- Time-aware
• Seamless Approach for serving Imagery- Regional processing versus a file- Color balancing- Seamline blending- Mosaics are virtual
On-the-Fly Processing
Dynamic Mosaics
Catalog Functions
Source Imagery
SourceMosaic
DatasetsDerived
Mosaic DatasetOrthometric Height
f
Single image service with multiple server functions
Example – ArcGIS World Elevation – Server Raster Functions
…many other functions
Aspect
Ellipsoidal Height
Slope
Hillshade
digital terrain model
digital surface model
normalized digital surface model
LiDAR
Imagery
Demo
Creating Elevation Services
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Networking ReceptionSmithsonian National Museum of the American IndianThursday, 6:30 p.m. – 9:30 p.m.Bus pickup on L Street
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GIS Solutions Expo, Hall AWednesday, 12:30 p.m. – 6:30 p.m.Welcome Social, 5:15 p.m. – 6:30 p.m.Thursday, 10:45 a.m. – 4:00 p.m.
• Exhibitors• Hands-on Learning Lab• Demo Theaters• Esri Showcase