ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD
description
Transcript of ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD
![Page 1: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/1.jpg)
ESTIMATION OFEARTHQUAKE DAMAGEFROM AERIAL IMAGES
BY PROBABILISTIC METHOD
Shota Izaka, Hitoshi Saji(Shizuoka University)
![Page 2: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/2.jpg)
Introduction
![Page 3: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/3.jpg)
Backgrounds• After large-scale earthquake
– Urban areas are seriously damaged– Many people require rescuing and aid
• For effective rescue and victim support– Rapid action is needed– A wide range of information is important
Aerial images are suitablefor disaster
observation
![Page 4: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/4.jpg)
Conventional method• Matching analysis
– Comparing pre-disaster and post-disaster images
• Difficulty of matching analysis– Difficult to obtain pre-disaster images– Affected by shooting conditions and time
• Changes of shadows• Construction and destruction of buildings
![Page 5: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/5.jpg)
Our goals• Rapid analysis of damage
– Use only post-disaster aerial images– Not using the training data
• Assisting various rescue and victim support activities– Providing information available for various
purposesAssisting human decisions
![Page 6: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/6.jpg)
Ways of assisting human decisions
• Remaining undetermined regions– We don’t force to classify all regions– The final decision is left to the people in the
field• Showing the likelihood of damages
– The result available for various purposes• Target area estimation of rescue activity• Determination of the road passable for
emergency vehicles
![Page 7: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/7.jpg)
Method
![Page 8: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/8.jpg)
Overview
Aerial Image Segmentation
Featureextraction
Resultfor buildings
Digitalmap
Regionclassification
Resultfor roads
Road mask creation
![Page 9: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/9.jpg)
Road mask creation• Creating road mask from digital map
– Roads change little over timeOur method is not affected by the
timewhen the map is created
Digital map Road mask
![Page 10: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/10.jpg)
Segmentation• Initial Segmentation
– Segment into small basic regions• Unification of similar regions
– Considering color and textures– Avoiding to unify roads and buildings
Before segmentation After segmentation
![Page 11: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/11.jpg)
Feature extraction• Collapsed buildings
– Segmented into small regions– Having short random edges
Extracting short edgesas a feature of damages
Collapsed buildings Segmented regions Edges
![Page 12: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/12.jpg)
Feature extraction• Undamaged buildings
– Maintaining their shapes– Having a large area
Extracting building regionsas a feature of
undamaged
Undamaged buildings Segmented regions Edges
![Page 13: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/13.jpg)
Region classification• Using the probabilistic relaxation
method– Labeling method using the probability
We use the method to classify each region by damage probability
![Page 14: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/14.jpg)
Defining initial probability• Considering extracted features
– The proportion of short edges– The area of region– Building region or not
Large area
BuildingHigh short edge rate
Probability definitions
![Page 15: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/15.jpg)
Probability update• Update using similarity
– Considering the region similar to damaged region as damaged region
Probability update model
Low
High
High
High
High
High
High
High
High
High
High
High
High
High
High
High
![Page 16: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/16.jpg)
Extracting undamaged regions
• Regions are converged high or low probability
• Extracting low probability regionsas undamaged
regions– Considering regions not converged
as undetermined regionsHigh
probability
Result of extraction
Low probability
Undetermined
![Page 17: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/17.jpg)
Extracting damaged regions• Extracting damaged regions
from high probability regions
Highprobability
Damaged regions extraction model
Lowprobability
Undetermined
Damaged
Undetermined
![Page 18: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/18.jpg)
Redefining initial probability• Redefining probability
by randomness of edges– Using variance of edge angles
Edge model ofundamaged buildings
Edge model ofcollapsed buildings
![Page 19: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/19.jpg)
Result of classification• ■:Undamaged regions• ■:Undetermined regions 1
– Low risk of damage• ■:Undetermined regions 2
– High risk of damage• ■:Damaged regions
Result of classification
Undetermined
Damaged
Undetermined
Undamaged
![Page 20: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/20.jpg)
Image division• Dividing a result image into buildings
and roads– Result of buildings
• Estimation of building damages– Result of roads
• Determination of road passable
![Page 21: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/21.jpg)
Experiment
![Page 22: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/22.jpg)
Data• Aerial images
– Great Hanshin Earthquake– Captured on January 18, 1995– Provided by PASCO Corp.
• Digital map– A topographic map of Kobe city– Provided by Kobe City Urban Planning
Bureau
![Page 23: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/23.jpg)
Result of classification for buildings
Input image Result image
■:Undamaged regions ■:Undetermined regions 1■:Undetermined regions 2 ■:Damaged regions
![Page 24: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/24.jpg)
Result of classification for roads
Input image Result image
■:Undamaged regions ■:Undetermined regions 1■:Undetermined regions 2 ■:Damaged regions
![Page 25: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/25.jpg)
Evaluation of accuracy• Creating answer images
– Using visual judgment• Comparing with results
Result of classification
Undetermined
Answer
Damaged UndamagedDamaged
Undamaged
Undetermined
![Page 26: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/26.jpg)
Detection rate• Evaluating pixels in same category
Result of classification
Answer
Damaged UndamagedDamaged
Undamaged
Damaged
Undamaged DamagedUndamaged
![Page 27: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/27.jpg)
Detection ratewith human decisions
• Estimating rate after human decisions– Adding undetermined regions
Result
Damaged
Undamaged
Answer
Damaged Undamaged
DamagedUndamaged
Damaged
Undamaged
![Page 28: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/28.jpg)
False detection rate• Evaluating pixels in wrong category
– Visual judgment
Considered undamaged regions
Damaged
Undamaged Considered damaged regions
Result of classification
DamagedUndamaged
![Page 29: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/29.jpg)
Answer for buildings
Result imageAnswer image
■:Undamaged regions ■:Undetermined regions 1■:Undetermined regions 2 ■:Damaged regions
![Page 30: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/30.jpg)
Answer for roads
Answer image Result image
■:Undamaged regions ■:Undetermined regions 1■:Undetermined regions 2 ■:Damaged regions
![Page 31: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/31.jpg)
Result of accuracy evaluation in buildings
• Undamaged regions– Detection rate:77.2%
• With human decisions:93.1%– False detection rate:10.1%
• Damaged regions– Detection rate:74.0%
• With human decisions:87.0%– False detection rate:17.7%
![Page 32: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/32.jpg)
Result of accuracy evaluation in roads
• Undamaged regions– Detection rate:85.5%
• With human decisions:93.4%– False detection rate:19.0%
• Damaged regions– Detection rate:65.3%
• With human decisions:79.6%– False detection rate:14.6%
![Page 33: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/33.jpg)
Review of results• Obtained high detection rates
– Except for damaged regions in roads• Features of damage on roads are unclear
– Many regions classified into “Undetermined”Requiring human decisions
Road image Result of classification
![Page 34: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/34.jpg)
Review of results• Obtained low false detection rates
– Roads have more errors than buildings• Caused by objects on roads
– Cars, roofs, shadows of buildings
Roof and car Error Shadow and car Error
![Page 35: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/35.jpg)
Conclusion• Our results can be used for various
rescue and victim support activity– Estimation of building damages– Determination of road passable
• Our future directions– Improving building detection– Detecting objects on roads
![Page 36: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/36.jpg)
End
![Page 37: ESTIMATION OF EARTHQUAKE DAMAGE FROM AERIAL IMAGES BY PROBABILISTIC METHOD](https://reader036.fdocuments.net/reader036/viewer/2022062811/568161bb550346895dd1930a/html5/thumbnails/37.jpg)
The Sendai earthquake• Most of the damage was caused by the
Tsunami• Most of the buildings are flooded out
– Our method aim to detect collapsed buildings
• Huge area of damage– Not possible to capture by aerial images
Applying to the earthquake is future works