Automatic urban debris zone extraction from post-hurricane very high-resolution satellite and aerial imagery

Figures & data

Figure 1. Study area location (Data source: United States Census Bureau).

Table 1. Post-Katrina remote sensing datasets for the study area.

Data description	Data source name/URL	Spatial extent (m)	Spatial resolution (m)	Data date	Format
IKONOS Imagery	DigitalGlobe http://www.digitalglobe.com/ Retrieved from: Mississippi Automated Resource Information System (MARIS) http://www.maris.state.ms.us/	900 × 630	1	2 September 2005	Panchromatic satellite
NOAA photography	National Oceanic and Atmospheric Administration (NOAA) http://ngs.woc.noaa.gov/katrina/	3000 × 2100	0.3	30 August 2005	Colour aerial

Figure 2. Debris zone and debris line extraction workflow.

Figure 3. Flowchart for debris zone extraction based on debris and non-debris classification result.

Figure 4. IKONOS data and classification results: (a) IKONOS-2 panchromatic image (Source: DigitalGlobe 2-Sep-05); (b) spectral only classification; (c) textural only classification; (d) spectral–textural classification (white = debris class, black = non-debris class).

Table 2. Case study operations and corresponding parameters for debris zone extraction based on imagery type and classification approach.

IKONOS			NOAA
Spectral only	Textural only	Spectral–textural	Spectral only	Textural only	Spectral–textural
D 3 (d) E 3 (d) S 5000 (nd) Ma 5 (d) S 2000 (d) D 3 (d) Mi 5 (d) S 1000 (d) D 3 (d)	Mi 3 (nd) S 900 (nd) Mi 5 (d) S 5000 (d) D 3 (d)	D 5 (d) S 3600 (nd) Mi 3 (d) E 7 (d) S 4000 (d) D 7 (d)	Mi 3 (nd) Ma 11 (nd) S 1000 (nd) Mi 3 (d) S 6000 (nd) D 3 (d) E 3 (d) D 3 (d) Mi 5 (d) S 100 (nd) S 4000 (d) D 3 (d)	E 5 (d) D 5 (d) Mi 3 (nd) Ma 5 (nd) E 5 (d) S 10000 (nd) D 3 (d) S 1200 (nd) E 3 (d) D 3 (d) S 2000 (nd) E 3 (d) D 3 (d)	E 3 (d) S 1000 (d) D 7 (d) S 1000 (nd) S 10000 (d) D 3 (d) Mi 5 (d) S 200 (d) S 500 (nd) E 3 (d) D 3 (d)

Notes:

D = dilate, connect non-contiguous debris/increase debris boundary.

E = erode, connect non-contiguous debris/decrease debris boundary.

S = sieve, remove isolated pixels.

Ma = majority, connect non-contiguous debris.

Mi = minority, connect non-contiguous debris.

d = debris class.

nd = non-debris class.

D and Ma are shown in bold text to convey their similar mathematical meaning.

E and Mi are shown with underlined text to convey their similar mathematical meaning.

Numerical values after D, E, Ma, Mi represent operation window size.

Numerical value after S represents selected threshold to remove isolated pixels.

Figure 5. Debris zone results for IKONOS imagery based on classification approach: (a) spectral only; (b) textural only; (c) spectral–textural (white = debris class, black = non-debris class).

Figure 6. Debris line results for IKONOS imagery (Source: DigitalGlobe 2-Sep-05) based on classification approach: (a) spectral only; (b) textural only; (c) spectral–textural.

Figure 7. NOAA imagery and debris line results based on classification approach: (a) resampled NOAA photo (Source: NOAA 30-Aug-05); (b) spectral only; (c) textural only; (d) spectral–textural.

Figure 8. (a) Comparison of debris zone results obtained from spectral–textural classification approach for IKONOS and NOAA imagery (interior boundary = identified as debris from both data types; grey = identified as debris in IKONOS imagery but non-debris in NOAA imagery; black = identified as debris in NOAA imagery but non-debris in IKONOS imagery). (b) Extracted IKONOS spectral–textural classification debris line compared with manually interpreted results from Friedland et al. (2011). Image source: DigitalGlobe 2-Sep-05.

Table 3. Debris zone areas (measured in pixels) extracted using the three different classification methods for IKONOS and NOAA imagery.

Imagery type	Image size	Spectral	Textural	Spectral–textural
IKONOS Panchromatic (1 m)	900 × 630	157,365	105,129	97,288
Resampled NOAA photo (1 m)	900 × 630	201,924	130,682	84,212

Table 4. Approximate processing time for debris zone extraction based on classification approach for case study image.

		Number of bands		Processing time
Classification approach	Classification method	IKONOS	NOAA	Image classification	Debris zone extraction	Total
Spectral only	Supervised	1 band	3 bands	20–40 minutes	90–120 minutes	110–160 minutes
Textural only	Unsupervised	1 band	1 band	5 minutes		95–125 minutes
Spectral-textural	Supervised	2 bands	4 bands	20–40 minutes		110–160 minutes

Friedland CJ, Massarra CC, Henderson E. 2011. Integrated aerial-based and ground-based damage assessment of single family dwellings at the neighborhood and per-building spatial scales. 9th International Workshop on Remote Sensing for Disaster Response; Stanford, CA.

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