lidar qa/qc and extracting building footprints · •to suggest future ctp webinar topics, please...
TRANSCRIPT
![Page 1: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/1.jpg)
Cooperating Technical Partners Information Exchange
LIDAR QA/QC and Extracting Building
Footprints
![Page 2: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/2.jpg)
Audio and Web Settings
Open and hide your control panel using the orange arrow button at top left corner
• Choose “Computer audio” to use computer speakers or headphones
• Choose “Phone call” to dial in using the information provided
Submit questions & comments via the Questions panel
Participation
![Page 3: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/3.jpg)
Webinar Logistics
• All lines will be automatically be muted.
• Use the Question window in the control panel to submit your question or comment to the Flood Science Center Organizer.
• Select questions will be read to the presenter and answered.
• Questions not asked during the webinar will be answered and posted to the CTP Webinar page.
![Page 4: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/4.jpg)
• Certified Floodplain Managers are eligible for 1 Continuing Education Credit for participating in this webinar.
• You must have registered individually and indicated you are a CFM at time of registration.
• Eligibility for CEC is dependent on your participation in poll questions and time spent viewing the webinar, as determined by the webinar software.
• Attending this webinar in a group setting or only viewing the recording is NOT eligible for CEC.
Continuing Education Credits
![Page 5: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/5.jpg)
• To suggest future CTP webinar topics, please contact Alan Lulloff at [email protected] or type a suggested topic into the Questions panel today.
• ASFPM CFM CECs will be automatically applied.
• Certificates of Attendance will be emailed, please contact [email protected] with any certificate issues.
• Follow-up email with link to slides and recording will be sent next week
Thank You for Joining Us!
Additional Logistics
![Page 6: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/6.jpg)
NGS Webinar: Vertical Datum Changes for Floodplain Mapping
https://www.ngs.noaa.gov/web/science_edu/webinar_series/flood-datums.shtml
![Page 7: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/7.jpg)
Coastal GeoTools 2019:Registration now open!
http://coastalgeotools.org
• Early-bird registration ends December 14th
![Page 8: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/8.jpg)
ASFPM Mapping and Engineering Standards Committee
Cooperating Technical Partners Sub-committee
Co-chairs:
• Thuy Patton, CFMColorado Water Conservation Board
• Carey JohnsonKentucky Department for Environmental Protection
Goals:
• Identify common concerns
• Provide opportunities for information exchange
• Identify training needs
• Promote and document the value of CTPs
![Page 9: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/9.jpg)
Agenda
Introduction - Alan Lulloff
LIDAR QA/QC - Lewis Graham
Building Footprint Feature Extraction - Lewis Graham
Questions/Discussion
![Page 10: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/10.jpg)
LIDAR QA/QC
Building Footprints
Lewis Graham
GeoCue Group Inc.
9668 Madison Blvd., Suite 202
Madison, AL 35758
256-461-8289
www.geocue.com
![Page 11: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/11.jpg)
WHAT IS LIDAR?
11ASFPM - LIDAR QA/QC, Footprints
![Page 12: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/12.jpg)
What Is LIDAR?
• Laser Imaging, Detection and Ranging (LIDAR) is the optical equivalent of
radar or sonar but using an optical source – a laser - instead of microwaves or
sound waves
• An optical pulse is emitted from a laser at a precisely known time, the pulse
reflects from something in the ‘object’ space and the instrument measures the
precise time a return pulse (“echo”) is detected
• The time of flight is converted to a distance to the target using the constant
speed of light
• The laser’s precise position and orientation is known via a “Positioning and
Orientation System” (POS). These supplemental data are used to derive the
object space position
12ASFPM - LIDAR QA/QC, Footprints
![Page 13: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/13.jpg)
How Does It Work?
• Compact, rugged instrument installed on a small aircraft
• Laser pulses scanned across the path of the aircraft measuring range to surface
• LIDAR ranges are combined with aircraft GPS position and Inertial Measurement Unit orientation information
• Post-processing software calculates X,Y,Z position of each spot on the surface
13ASFPM - LIDAR QA/QC, Footprints
![Page 14: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/14.jpg)
Modern LIDARs can detect
Multi-Returns (“echoes”)
14ASFPM - LIDAR QA/QC, Footprints
![Page 15: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/15.jpg)
Laser Return Intensity
ASFPM - LIDAR QA/QC, Footprints 15
Typical Wavelengths:Wide area mapper 1.064 microns
Corridor mapper 1.541 microns
![Page 16: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/16.jpg)
Point Cloud
ASFPM - LIDAR QA/QC, Footprints 16
Because of sensor mechanics and ground undulation, the points are not uniform
Because the points are true 3D, they cannot be represented by a raster such as a DEM
![Page 17: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/17.jpg)
Important Point Attributes
• Attributes produced by the laser scanner:
– Absolute time of pulse
– Position (X, Y, Z)
– Intensity (echo energy)
– Return number (e.g. return “n of m”)
– Edge of flight line
– Scan angle
• All of the above are very important to advanced
processing algorithms
ASFPM - LIDAR QA/QC, Footprints 17
![Page 18: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/18.jpg)
Typical Point Cloud Products(In all cases, we assume geometrically corrected clouds)
• “Unclassified” - All returns, unclassified point cloud
• “Surface” cloud - This is a first return, unclassified cloud. No need for this if you specify the “all returns” data
ASFPM - LIDAR QA/QC, Footprints 18
• “Bare Earth” classified cloud -Classified ground, Classified Noise, tagged “overlap” points - should include all other points (unclassified)
• Supplemental classes – Classified
ground + Vegetation, Buildings, etc.
![Page 19: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/19.jpg)
Feature Extraction
• Water bodies
• Shoreline
• Planar surfaces
– Roof footprints, etc.
• Tree envelopes
• Specialty assets– roads, bridges, rails, etc.
ASFPM - LIDAR QA/QC, Footprints 19
![Page 20: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/20.jpg)
LIDAR PARAMETERS
20ASFPM - LIDAR QA/QC, Footprints
![Page 21: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/21.jpg)
Density
ASFPM - LIDAR QA/QC, Footprints 21
Higher Density
Lower Density
![Page 22: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/22.jpg)
Point Spacing/Density
Measurement• Measured as:
– Density - Points per unit area (e.g. points per square
meter, ppm)
– Nominal Point Spacing (NPS) – average distance
between points
– Ground Sample Distance (GSD) – same as NPS
22ASFPM - LIDAR QA/QC, Footprints
(e.g. A 40 ppm helicopter scan has an NPS of ~16 cm)
![Page 23: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/23.jpg)
USGS Quality Levels
ASFPM - LIDAR QA/QC, Footprints 23
NOTE: USGS is still not specifying horizontal accuracy
![Page 24: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/24.jpg)
DEMO – LIDAR VIEWING
SAMPLES
24ASFPM - LIDAR QA/QC, Footprints
![Page 25: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/25.jpg)
DATA APPLICATIONS
25ASFPM - LIDAR QA/QC, Footprints
![Page 26: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/26.jpg)
What Is LIDAR Mapping?
• It is a tool used in the airborne survey field that employs LIDAR to rapidly generate elevation data that are:
• high-density
• accurate
• digital
• geo-referenced
• Can be both a complementary or competitive technology to photogrammetry
• Complete data sets should include imagery
26ASFPM - LIDAR QA/QC, Footprints
![Page 27: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/27.jpg)
Typical Point Cloud Products(In all cases, we assume geometrically corrected clouds)
• All returns, unclassified point cloud
• “Surface” cloud
– This is a first return, unclassified cloud. No need for this if you
specify the all returns data
• “Bare Earth” classified cloud (typical 3DEP delivery)
– Should include all other points but unclassified
• Supplemental classes;
– Vegetation
– Buildings
– etc.
ASFPM - LIDAR QA/QC, Footprints 27
![Page 28: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/28.jpg)
Supplemental LIDAR Derived
Data• Breaklines - Hydro
– Water bodies (“flattening”)
– Downstream constraints
– Double line drains
• Breaklines – Other
– Edge of pavement
– Retaining walls
– (Geo)Morphological interest
ASFPM - LIDAR QA/QC, Footprints 28
![Page 29: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/29.jpg)
Feature Extraction
• Water bodies
• Shoreline
• Planar surfaces (e.g. building roofs)
• Building “roof prints”
• Tree envelopes
• Specialty assets– roads, bridges, rails, wires, etc.
ASFPM - LIDAR QA/QC, Footprints 29
![Page 30: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/30.jpg)
Visualization
• LIDAR “Orthos”
• 3D visualization
• Profiles
ASFPM - LIDAR QA/QC, Footprints 30
![Page 31: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/31.jpg)
Output products
• Gridded elevation models
– Canopy
– Surface
– Breakline enforced surface
• Topographic Contours
• Raster visualization products
• Features
• Derived analytics such as volumetrics
ASFPM - LIDAR QA/QC, Footprints 31
![Page 32: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/32.jpg)
Cost Factors
ASFPM - LIDAR QA/QC, Footprints 32
Cost
increasing
quality of factor
![Page 33: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/33.jpg)
QA, QC
ASFPM - LIDAR QA/QC, Footprints 33
Quality Assurance (QA) – Preventing Defects
Quality Control/Check (QC) – Identifying Defects
Independent Validation and Verification (IV&V) –
An independent (from the contractor) QC function
Sometimes small repairs are considered part of a QC task but I would recommend these be kept separate
![Page 34: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/34.jpg)
Ignoring QC
• With LIDAR, you typically find the issues months or
years after the fact
• Secondary product derivation may be impossible
• Stakeholders lose some percentage of their
investment
• Persons involved in the procurement lose credibility
• Often the technology (LIDAR), rather than the
process, is blamed.
ASFPM - LIDAR QA/QC, Footprints 34
![Page 35: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/35.jpg)
Typical QC flow
ASFPM - LIDAR QA/QC, Footprints 35
Load into Data System
Incrementally Receive Tiles
Location Check
Gross Coverage
Check
Inter-Swath Accuracy
Density Testing
Classification Quality
Breakline Validation
Product Specific Checks
Gross Radiometry
Check
Gross Returns Check
SRS CheckNetwork Accuracy
![Page 36: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/36.jpg)
Coverage
ASFPM - LIDAR QA/QC, Footprints 36
![Page 37: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/37.jpg)
Gross Void Checks
ASFPM - LIDAR QA/QC, Footprints 37
![Page 38: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/38.jpg)
Network Accuracy
ASFPM - LIDAR QA/QC, Footprints 38
![Page 39: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/39.jpg)
Local Accuracy
• Poor Alignment
– Image Swaths
• Look at Flight Overlap
• Examine Surface
• Examine Cross-Sections
– Buildings in Overlap
– Roads
– Parking Lots
ASFPM - LIDAR QA/QC, Footprints 39
![Page 40: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/40.jpg)
Good Radiometry
ASFPM - LIDAR QA/QC, Footprints 40
![Page 41: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/41.jpg)
Returns
ASFPM - LIDAR QA/QC, Footprints 41
![Page 42: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/42.jpg)
High Noise
ASFPM - LIDAR QA/QC, Footprints 42
![Page 43: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/43.jpg)
Low Noise
ASFPM - LIDAR QA/QC, Footprints 43
![Page 44: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/44.jpg)
Density Test
ASFPM - LIDAR QA/QC, Footprints 44
4.21 ft
![Page 45: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/45.jpg)
Error Identification:
Pits, Spikes &Undulations• Pits
– Anomalies
• Spikes
– Atmospheric Particles
– Anomalies
• Undulations
– IMU Measurement/Calibration
Error
(Shrethsa et al., 2009)
ASFPM - LIDAR QA/QC, Footprints 45
![Page 46: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/46.jpg)
Classification Accuracy
ASFPM - LIDAR QA/QC, Footprints 46
B = Building
V = Vegetation
C = Car
G = Ground
A Classification “Confusion” Matrix
(misclassified Ground and Building
![Page 47: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/47.jpg)
Breakline Checks
ASFPM - LIDAR QA/QC, Footprints 47
Breakline errors
Flat water body (correct)
![Page 48: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/48.jpg)
Communicate Spatially!
ASFPM - LIDAR QA/QC, Footprints 48
![Page 49: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/49.jpg)
QC-FOCUSED DEMOS
ASFPM - LIDAR QA/QC, Footprints 49
![Page 50: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/50.jpg)
Poll Question
QC of LIDAR data upon receipt is very important because:
> Problems that are not detected early in the delivery cycle are difficult to refer back to the collection contractor
> Properties valuable to data extraction such as multiple returns may not have been examined in the contractor QC phase
> Many LIDAR collects place the majority of the QC emphasis on the ground surface quality only
> You may not have received the full point cloud
> All of the above
![Page 51: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/51.jpg)
BUILDING EXTRACTION
ASFPM - LIDAR QA/QC, Footprints 51
![Page 52: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/52.jpg)
A Point’s View of a Building
ASFPM - LIDAR QA/QC, Footprints 52
Unclassified TreeUnclassified Roof Surface
Classified GroundUnclassified Ground
Unclassified ???
![Page 53: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/53.jpg)
Useful metrics
ASFPM - LIDAR QA/QC, Footprints 53
Not Planar
Is Planar
Vertically separated from Ground
Not Vertical
Has Area larger than X
Is Not Classified as Ground
![Page 54: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/54.jpg)
Problems
ASFPM - LIDAR QA/QC, Footprints 54
Tree (or other) points over roof
Unclassified ground points
Sparse roof areas
![Page 55: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/55.jpg)
Problems (cont)
ASFPM - LIDAR QA/QC, Footprints 55
Noise relative to “best fit” plane
Undefined planar intersections
![Page 56: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/56.jpg)
Problems (cont)
ASFPM - LIDAR QA/QC, Footprints 56
Poor edge definition
![Page 57: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/57.jpg)
Extraction – PlanesPrincipal Component Analysis (PCA)
ASFPM - LIDAR QA/QC, Footprints 57
For each plane, derive Centroid (where is the center of the plane) and Normal (what is the elevation and azimuth?)
![Page 58: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/58.jpg)
Planar Factors
ASFPM - LIDAR QA/QC, Footprints 58
How many contiguous points fit the plane (growing)?
How far do we allow a point to deviate from the plane (noise)?
What is the minimum required size of the plane?
What is the minimum and maximum slope of the plane?
What is the minimum height of the plane above ground?
What is the maximum height of the plane above ground?
![Page 59: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/59.jpg)
Traced Classified Planes
ASFPM - LIDAR QA/QC, Footprints 59
![Page 60: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/60.jpg)
Squaring
ASFPM - LIDAR QA/QC, Footprints 60
![Page 61: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/61.jpg)
Reality
ASFPM - LIDAR QA/QC, Footprints 61
![Page 62: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/62.jpg)
BUILDING EXTRACTION DEMO
ASFPM - LIDAR QA/QC, Footprints 62
![Page 63: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/63.jpg)
Poll Question
The most significant factors that can impact the ability of automated tools to
extract building outlines (roof/footprint).> RGB colors of the points
> Point noise level and point density
> The wavelength of the laser
> The altitude of the sensor
> None of the above
![Page 64: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/64.jpg)
Summary
• “All Points” data with ground classified are
invaluable for a myriad of information extraction
tasks
• High noise and low density are the enemies of high-
quality extraction
• Some level of QC should be implemented
regardless of the flow path to you
• Low cost desktop tools can be used post-acquisition
to add considerable value to dataASFPM - LIDAR QA/QC, Footprints 64
![Page 65: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/65.jpg)
Questions&
Discussion
Alan Lulloff
Lewis Graham
Cooperating Technical Partners
Information Exchange
![Page 66: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/66.jpg)
Poll Question
Please rate this webinar.
![Page 67: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/67.jpg)
• Certified Floodplain Managers are eligible for 1 Continuing Education Credit for participating in this webinar.
• You must have registered individually and indicated you are a CFM at time of registration.
• Eligibility for CEC is dependent on your participation in poll questions and time spent viewing the webinar, as determined by the webinar software.
• Attending this webinar in a group setting or only viewing the recording is NOT eligible for CEC.
Continuing Education Credits
![Page 68: LIDAR QA/QC and Extracting Building Footprints · •To suggest future CTP webinar topics, please contact Alan Lulloff at alan@floods.org or type a suggested topic into the Questions](https://reader031.vdocument.in/reader031/viewer/2022011908/5f5a0bcf9522a618a9087dcf/html5/thumbnails/68.jpg)
• To suggest future CTP webinar topics, please contact Alan Lulloff at [email protected] or type a suggested topic into the Questions panel today
• ASFPM CFM CECs will be automatically applied
• Certificates of Attendance will be emailed, please contact [email protected] with any certificate issues
• Follow-up email with link to slides and recording will be sent next week
Thank You for Joining Us!
Closing Comments