LiDAR for Urban Change Detection Keith W. Cunningham, PhD Alaska Satellite Facility November 13, 2009
LiDAR LiDAR Light Detection and Ranging Building Footprints GIS outlines (planimetrics) GIS Geographic Information System Planimetrics GIS data of buildings & curbs Change Detection Comparing differences in data 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 1
LiDAR Scanning Laser Sweeps the ground Scan perpendicular to flight line 0.10 cm The laser beam diverges More divergence with distance The laser samples the ground Oblique samples are larger 0.10 cm 1,000 meters 2,000 meters 25 cm 70 cm 50 cm 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 2
LiDAR Returns First Return Second Return One Return Third Return Last Return 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 3
LiDAR vs. Photogrammetry Photogrammetry requires 2 separate views of a point to measure Z. LiDAR only requires one ground return to measure Z, so it is more efficient than photogrammetry. 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 4
LiDAR Data & Postings ASCII data with XYZ posting values same data rendered in a GIS layer. 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 5
LiDAR Postings Postings are not a regular grid, rather an irregular sampling. 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 6
LiDAR Swath Overlap 3rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 7
LiDAR Point Cloud 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 8
LiDAR Classification 3rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 9
LiDAR Modelling (a) (b) (c) Feature Extraction a) Aerial image. b) Elevations as gray value image. c) Gradient magnitude image. d) LiDAR postings & TIN e) Edge & Corner Detection Martin Huber, et al 2007 (d) (e) 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 10
LiDAR Edges & Corners 3rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 11
Masking Example 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 12
Draping Example Obliques Pictometry Bird s Eye 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 13
LiDAR Mask Dilation 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 14
LiDAR Footprint Extraction 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 15
LiDAR & Planimetrics 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 16
LiDAR vs. Heads-Up Digitizing Id Roof Lidar Diff 0 1526 1490 97.6% 1 1371 1360 99.2% 2 1566 1910 122.0% 3 2519 2460 97.7% 4 1648 1610 97.7% 5 1767 1790 101.3% 6 1746 1760 100.8% 7 2071 1990 96.1% 8 1506 1670 110.9% 9 2495 2240 89.8% 10 1965 1690 86.0% 11 809 1030 127.3% 12 378 na 13 1828 1680 91.9% 14 1888 1670 88.5% 15 1508 1530 101.5% 16 1531 1380 90.1% 17 1782 1490 83.6% 18 2050 2100 102.4% 19 1677 1630 97.2% 20 1815 1700 93.7% 21 1528 1410 92.3% 22 1287 1080 83.9% 23 781 658 84.3% 24 1388 1590 114.6% 25 1197 1240 103.6% 26 2285 2280 99.8% 27 2160 2070 95.8% 28 1630 1710 104.9% Average % 98.4 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 17
LiDAR Change Detection Create LiDAR structure Mask Compare Structure Footprint with Mask Automated Change Detection In a spreadsheet Map Algebra 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 18
3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 19
LiDAR Ratio Analysis 1.8 meter postings Structure Masking Auto Change Detection using Ratio Analysis 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 20
LiDAR Decision Tree New Feature: Pink & Yellow Missing Feature: Black No Change: White Possible Change: Gray Similar to a medical test with true positives & negatives and false positives & negatives 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 21
Change Validation 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 22
LiDAR & Relief Displacement Oblique Pictometry Bird s Eye 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 23
Thank You Keith W. Cunningham, PhD Alaska Satellite Facility 3 rd ALOS Joint PI Symposium, 9-13 Nov. 2009 Keith W. Cunningham, PhD 24