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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