Hosted by Esri

Official Distributor

3D Analyst Lidar Solutions

Peter Becker

Esri European User Conference October 15-17, 2012 | Oslo, Norway

Agenda

• Introduction to Lidar • Lidar and LAS datasets • Lidar and terrain datasets • Lidar and Mosaic datasets • Sharing Lidar

Lidar – Light detection and ranging

• Lidar (light detection and ranging) is an optical remote-sensing technique that uses laser light to densely sample the surface of the earth, producing highly accurate x,y,z measurements.

• Laser pulses emitted from a Lidar system reflect from objects both on and above the ground surface.

Types of Lidar

• Airborne - Captured from aircraft - Suitable for surface analysis

• Terrestrial - Captured from the ground - Suitable for feature location and data validation

Dense data can have elements of both

Multiple laser returns Lidar data

First Return

SecondReturn

ThirdReturn

Last Return

Digital surface model creation from Lidar Lidar data

First Return

SecondReturn

ThirdReturn

Last Return

DSM

Digital elevation model creation from Lidar Lidar data

First Return

SecondReturn

ThirdReturn

Last Return

DSM

DTM

Surface using breaklines Lidar data

Breaklines may be required for less dense lidar or for terrain form enforcement

First Return

SecondReturn

ThirdReturn

Last Return

DSM

DTM Breakline

Lidar Preprocessing

Acquisition Point Clouds Pre-Processing

• Sensor calibration • Georeferencing • Q/A & Q/C? • Automated classification? • Tiling?

File01.las File02.las … File99.las

Multiple Files

/ Folders

Lidar storage

• Lidar data is commonly stored in LAS files • A LAS file is a binary file format for Lidar data storage

developed by the ASPRS in conjunction with private and government stakeholders.

• Each LAS file contains metadata of the Lidar survey in a header block followed by individual records for each laser pulse recorded.

Lidar classification

• Lidar points can be grouped together into classes that represent similar features.

• Defined by the ASPRS.

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?

Previous ArcGIS 10.0 support for Lidar

• Geodatabase oriented - Import ASCII or LAS - Multipoints - Terrain dataset

• Point To Raster tool • Terrain and TIN-based surface tools • Help

- Terrain concepts book - 3D Analyst tutorial terrain exercise - 3D Analyst ‘Lidar solutions in ArcGIS’ guide book

LAS support in ArcGIS 10.1

File01.las File02.las … File99.las

Multiple Files / Folders Tiled / Overlapping

Extents (Location / Time)

P R O J E C T S

O R G A N I Z E

Analyze / Update Data

Manage Serve / Share

Mosaic Dataset

LAS Dataset

1

LAS Dataset

2 LAS/Terrain Datasets

LAS Dataset

3

Using Lidar as a LAS dataset

• New data type • File based • Stores references to LAS files on disk • Optionally reference breakline & constraint data • Treats a collection of LAS files as one logical dataset

LAS Dataset Strengths

• Direct access to LAS • Catalog of LAS files for a project • View as points, TIN • Direct measurements • Statistics, Q/A & Q/C • Filter, query • Profile, 3D • Edit LAS • Add and edit constraints

LAS Dataset Creation

• Interactively via Catalog - File folder context menu pick

• Inside scripts and models with GP tools

LAS dataset properties

LAS Dataset / LAS File Statistics

Viewing Lidar as a LAS dataset

• In 2D (ArcMap) or 3D (ArcScene) • As points

- Symbolize using LAS attributes (Class Codes, RGB, Scan Angle, etc.)

• As a surface - Symbolize & filter using surface options

(Bare earth, First return, etc.)

• Control the number of points shown - Full resolution in a local area

Data courtesy Merrick & Co.

LAS Dataset – Editing Class Codes

• Manual - Fixing data anomalies and misclassifications via

point profile window

• Process (GP tools) - Classify relative to feature data - Reclassify to standard LAS spec

• Automated - Done by Partners

Interactive Editing

Batch Oriented Editing

Reclassify old class to new class

Set class by proximity to feature data

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

Airborne vs. terrestrial Lidar

• Most tools primarily for airborne Lidar - Surface views and analysis - LAS attributes

• Terrestrial Lidar supported primarily as point cloud in ArcScene

- Points used as backdrop for measuring and digitizing - Display integrated with other GIS layers

LAS dataset

Modeling Elevation Options

• LAS • Terrains • Raster

Terrain Dataset

• Points & constraints

• Stored in the geodatabase

• Schema: Defines feature class participation

• On-the-fly TIN

• Multi-resolution (pyramid z tolerance)

• Highly scalable & I/O efficient

• Attributes

• Editable, versioned

• For high quality surfaces

Points and Breaklines

Terrain Pyramids

Low Resolution Medium Resolution High Resolution

Multi-resolution surface created from measurements stored in feature classes

Terrain Dataset used to Define Managed Surface Lidar data

Terrains efficiently store and mange the terrain form

First Return

SecondReturn

ThirdReturn

Last Return

DSM

DTM Breakline

Terrain dataset editing

• Updates accomplished through edits to source measurements

- Append, remove, replace mass points by area - Standard/custom edit tools (e.g. Standard ArcGIS license)

used to modify polylines, polygons, spot heights - Terrain rebuild based on dirty-areas

• Support for versioning in SDE

Creating a terrain dataset

Viewing Lidar as a terrain dataset

• Symbology same as TIN in ArcMap • Resolution changes depending on zoom level in ArcMap • Terrain datasets can be displayed as either elevation or

draped layers in ArcGlobe • Terrain datasets are not directly supported in ArcScene

Analysis capabilities for terrain datasets

• QA/QC Lidar data • DEM / DSM creation • Slope, Aspect, Contours • Surface differencing • Intensity image generation • Estimating forest canopy • Data area delineation • Thinning / reducing noise • Spot interpolation • Profiling

Raster (Regular Grid) Advantages

• Very Compact • Very Fast Access • Simple Viewing • Simple Analysis • Multiple derivatives But Courser approximation Can not define breaklines Generated from LAS or Terrains As a Derived Product or On-The-Fly

Using Mosaic Datasets to Manage and Serve Lidar

Image Management Workflow – Using Mosaic Datasets

• Create Catalog of imagery • Reference Source

• Ingest & Define Metadata

• Define Processing to be Applied

• Define Imagery Products • Dynamic Mosaicking • On-the-fly Processing

• Access as Image or Catalog

Highly Scalable, from Small to Massive Volumes of Imagery

Desktop

Mosaic Dataset Large Image

Collections

Image Dissemination – ArcGIS Server

• Dynamic Image Services • Processing & Analysis

• Catalog of Metadata

• Static Cached Imagery • Simple Backdrop

• Geoprocessing Services • Processing Tasks

Making Imagery Accessible to Desktop, Web and Mobile Apps

Desktop

Mosaic Dataset Large Image

Collections Server On Premise or In Cloud

Desktop, Web & Mobile Users

Using Lidar in Mosaic Datasets

• Lidar sources treated as raster type - LAS file

- Individual - Folder

- LAS Dataset - Terrain Dataset

• Must set properties to control the surface generation

- Pixel size - Return types - Classification types

Provides dynamic rasterization, mosaicking, and on-the-fly processing

Dynamic mosaicking and rasterization

• Display multi-resolution data together • Mosaicking rules

- Control the order of display - By attribute - Closest to center

- Ensure best data is always displayed - Can be controlled by user

• Queries - Refine selection of data

On-the-fly processing

• Data is processed as it is accessed • Create multiple products from one source • Processing for elevation

- Hillshade - Shaded Relief - Aspect - Slope - Convolution Filters

• Define processing functions - On each item - On entire collection

Benefits of managing Lidar with the mosaic dataset

• Store multiple collections and projects • Store variety of elevation data

- Topographic or bathymetric - Point or raster

• Unlimited size • Provide access to all data

- As raster - As source data - Share internally and online

Manage and share using a mosaic dataset

• Optimum model for Lidar and image data management • Manage

- Multiple projects as single dataset - Metadata

• Visualize and process - As 2D or 3D surface - DEM, hillshade, slope, etc.

• Share - As a single dataset - As image service

Using a mosaic dataset

• As an image - Seamless display - Perform pixel-based analysis - Use as an input to geoprocessing tool - Export a raster dataset

• As a catalog - Selection/query - Add selected images to map - View data and metadata - Time aware

Sharing Lidar data

• Share as image services • Easy to

- Access - Discover - Download

How to serve Lidar data

• Image service - Lidar data (or imagery) added to a mosaic dataset and made

available by a server to a client application - Requires the Image Extension - Access • Discover • Download

• Map service

- Point data, terrain dataset, or mosaic dataset* added to a map document and made available by a server to a client application

- Views map layer as it was designed

* requires Image Extension

Access, discover, and download

LAS files Image service

LAS dataset

Catalog/table Rasterized surfaces

New

VIEW/QUERY

DOWNLOAD

Multiple Elevation Data Sources Constraints

LAS files LAS Dataset Terrains Raster grids

Multiple Elevation Data Sources

Mosaic Dataset

Constraints

LAS files LAS Dataset Terrains Raster grids

• Catalog of data sources • Contains metadata • Defines processing • Directly accessed

Multiple Elevation Data Sources

Web Mobile Desktop

Mosaic Dataset

Constraints

LAS files LAS Dataset Terrains Raster grids

• Catalog of data sources • Contains metadata • Defines processing • Serve to many applications

Questions?