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February 2010 Volume 76, Number 2

Special Issue: Geographic Object-Based Image Analysis (GEOBIA)

Cover.indd 1 1/15/2010 2:04:31 PM

PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING Februar y 2010 121

From global climate change to natural disaster response and national

defense, remote sensing has provided critical information on vast areas of

the Earth’s surface for over 30 years, and continues to do so today. Daily,

terabytes of data are acquired from space- and air-borne platforms, result-

ing in massive archives with incredible information potential; however it

is only recently that we have begun to mine the spatial wealth of these

archives. In essence, we are data rich, but geospatial information poor. In

most cases, data/image access is constrained by technological, national,

and security barriers, and tools for analyzing, visualizing, comparing, and

sharing these data and their extracted information are still in their infancy.

Furthermore, policy, legal, and remuneration issues related to who owns

(and are responsible for) value-added products resulting from the original

data sources, or from products that represent the culmination of many

different users input (i.e., citizen sensors) are not well understood and still

developing. Thus, myriad opportunities exist for improved geospatial in-

formation generation and exploitation.

Over the last decade a quiet paradigm shift in remote sensing image

processing has been taking place that promises to change the way we

think about, analyze and use remote sensing imagery. With it we will have

moved from more than 20 years of a predominantly pixel-spectra based

model to a dynamic multiscale object-based contextual model that at-

tempts to emulate the way humans interpret images (Hay and Castilla,

2008). However, along this new path from pixels, to objects, to (geo-)in-

telligence and the consolidation of this new paradigm, there are numerous

challenges still to be addressed (Hay and Castilla, 2006). In an effort to

better identify these challenges and their potential solutions the interna-

tional conference GEOBIA, 2008 – Pixels, Objects, Intelligence: Geo-

graphic Object Based Image Analysis for the 21st Century was held at the

University of Calgary, Alberta, Canada, 05–08 August, 5–8 in partnership

with the Canadian Space Agency, the American Society for Photogram-

metry and Remote Sensing (ASPRS), and the International Society for

Photogrammetry and Remote Sensing (ISPRS). In total, 137 participants

from 19 different countries attended this conference that included eight

industry led workshops, three keynote addresses, and 65 regular oral pre-

sentations. A special joint session titled “GEOBIA in Support of Govern-

ment of Canada Needs” was also held, as were poster sessions and a stu-

dent award for best paper/presentation. A key objective of the conference

was to facilitate a forum for this growing international community, and to

share in the latest developments of GEOBIA theory, methods, and appli-

cations. Our theme — “Pixels, Objects, Intelligence: GEOgraphic Ob-

ject-Based Image Analysis for the 21st Century” was intended to highlight

this goal, as well as the evolution of this new discipline. GEOBIA (pro-

nounced ge-o-be-ah) is a sub-discipline of GIScience devoted to develop-

ing automated methods to partition remote sensing imagery into mean-

ingful image-objects, and assessing their characteristics through scale

(Hay and Castilla, 2008). Its primary objective is the generation of geo-

graphic information (in GIS-ready format) from which new geo-intelli-

gence can be obtained (Hay, 2008). Here, geo-intelligence is defi ned as

geospatial content in context.

Interest in GEOBIA is worldwide and rapidly evolving. GEOBIA 2008

built upon the success of OBIA 2006 (Lang et al., 2006) — the 1st Inter-

national Conference on Object Based Image Analysis — held in Salzburg

Austria, which was attended by over 120 participants from 24 different

countries. An edited book (Blaschke et al., 2008) was published from

extended peer-reviewed OBIA 2006 conference papers, and OBIA and

GEOBIA Wikis have been developed to facilitate community interaction

with of over 20,000 combined views (Wiki, 2009). More recently, Bl-

aschke (2009) conducted a comprehensive literature review, analyzing

more than 820 OBIA/GEOBIA related articles (comprising 145 journal

papers, 84 book chapters, and nearly 600 conference papers). From this

review, it is evident that the early developmental years of OBIA/GEOBIA

were characterized by a dominance of grey literature; however, over the

last four to fi ve years the number of peer-reviewed journal articles has

increased sharply. This suggests that an image-processing paradigm shift

is indeed taking place within the remote-sensing community. Similarly,

GEOBIA 2008 website statistics (from 12 April 2007–05 August 2008)

revealed 58,623 conference page views from all over the world (Figure

1). Specifi cally, these views represent 17,209 visits from 5,865 individu-

als in 111 different countries/territories spread over 1,647 unique cities.

Figure 1. GEOBIA 2008 web statistics, showing examples of major page-view locations from around the world (source: Google Statistics )

In order to provide greater dissemination of the information shared

during GEOBIA 2008, conference proceedings (Hay et al., 2008) are

freely available from two online sources1. In addition, three new peer-re-

viewed GEOBIA related special journal issues are either underway (Al-

pin and Smith, 2010) or in preparation (Johansen and Bartolo, 2010;

Addink, 2011). We also note that GEOBIA 2010 will be held (29 June–02

July, 2010) in Ghent, Belgium (http://geobia.ugent.be/), with planning

already in-progress for GEOBIA 2012.

In support of the GEOBIA 2008 conference theme, this special issue is

composed of three main areas: We begin with two papers representing the

pixel theme. Johansen et al., present a comparison of geo-object- and pix-

el-based change detection applied to a high-resolution multispectral forest

scene, followed by Kim et al., describing two studies that illustrate the

importance of incorporating both spectral and non-spectral ancillary data

for GEOBIA vegetation classifi cations from very high resolution (VHR)

imagery. Within the object theme, Lizarazo and Barros present a new fuzzy

Foreword

Special Issue: Geographic Object-Based Image Analysis (GEOBIA) by Geoffrey J. Hay and Thomas Blaschke

1. Two online archives of GEOBIA 2008 proceedings may be found at (http://www.ucalgary.ca/geobia/Publishing) and (http://www.isprs.org/publications/archives.aspx) (last date accessed 02 December 2009).

February Layout 2.indd 121 1/15/2010 1:05:17 PM

122 Februar y 2010 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING

image segmentation method for urban land-cover classifi cation, followed

by Smith, who argues for incorporating and exploiting existing digital car-

tography within the GEOBIA framework. This leads to a related study by

Radoux and Defourny who describe an automated GEOBIA method to

detect discrepancies between an existing (vector) forest map and a VHR

image. The fi nal theme is intelligence — referring to geo-intelligence —

which denotes the “right (geographically referenced) information” (i.e., the

content) in the “right situation” so as to satisfy a specifi c query or queries

within user specifi ed constraints (i.e., the context). The fi rst paper in this

section by Moreno et al., describes a novel geographic object-based vector

approach for cellular automata modeling to simulate land-use change that

incorporates the concept of a dynamic neighborhood. This represents a

very different approach for partitioning a scene, compared to the commonly

used GEOBIA segmentation techniques, while producing a form of tempo-

ral geospatial information with a unique heritage and attributes. The fi nal

paper by Tiede et al., presents a fully operational workfl ow for the model-

ing of 31,698 biotope complexes at the regional level with geo-objects and

a-priori knowledge. It represents one of the few published (to date) meth-

odologically sound, yet operational and transferable, approaches to semi-

automatically delineate biotope complexes.

Due to publication limitations, we regret that a number of very worthy

manuscripts were unable to be included in this special issue. Initially 21

papers were submitted, only seven have been published. Our objective in

selecting these papers is to provide a broad and relatively comprehensive

sample of the many different kinds of research topics that are being ad-

dressed with Geographic Object-Based Image Analysis. We also wish to

thank the 54 reviewers involved in the double- (and sometimes triple-)

blind review process, whose comments have enhanced the high quality

contributions found in this special issue. For those seeking additional re-

sources, we invite you to further peruse the OBIA 2006 and GEOBIA

2008 proceedings, to sample the 43 chapters of the recent book by Bl-

aschke et al., (2008) and to join us in Ghent, Belgium for GEOBIA 2010.

ReferencesAddink, E., (editor), 2011. GEOBIA 2011: Special Issue, Journal of Ap-

plied Earth Observation and Geoinformation (in progress).

Alpine, P., and G. Smith (editors), 2010. Special Issue on Object-Based

Landscape Analysis, International Journal of Geographical Informa-

tion Science (in progress).

Blaschke,T., 2009. Object Based Image Analysis for Remote Sensing, IS-

PRS Journal of Photogrammetry and Remote Sensing, in press, 42 p.

Blaschke,T., S. Lang, and G.J. Hay (editors), 2008. Object-Based Image

Analysis, Spatial concepts for knowledge-drives remote sensing appli-

cations, Series: XVII, Lecture Notes in Geoinformation and Cartogra-

phy, Springer-Verlag, p.818, 304 illustrations with CD-ROM, ISBN:

978-3-540-77057-2, URL: http://www.springer.com/978-3-540-77057-

2 (last date accessed: 02 December 2009).

Hay, G.J., 2009. GEOgraphic Object-Based Image Analysis (GEOBIA),

Developing a new sub-disclipline in GIScience, Oral presentation and

abstract, 20-22 Feb, Spatial Knowledge and Information – Canada, Fer-

nie, B.C., URL: http://rose.geog.mcgill.ca/ski/ (last date accessed: 02

December 2009).

Hay, G.J., T. Blaschke, and D. Marceau (editors), 2008. Proceedings of

GEOBIA 2008 – Pixels, Objects, Intelligence. GEOgraphic Object

Based Image Analysis for the 21st Century, University of Calgary, Cal-

gary, Alberta, Canada, 05–08 August, ISPRS Vol. XXXVIII-4/C1, Ar-

chives ISSN No. 1682-1777, 373 p., URL: http://www.ucalgary.ca/geo-

bia/Publications (last date accessed: 02 December 2009).

Hay, G.J., and G. Castilla, 2008. Geographic Object-Based Image Analy-

sis (GEOBIA): A new name for a new discipline?, in Object-Based Im-

age Analysis – Spatial Concepts for Knowledge-driven Remote Sensing

Applications, T. Blaschke, S. Lang, and G.J. Hay (editors), Springer-

Verlag, Chapter 1.4, pp. 81- 92.

Hay, G.J., and G.C. Castilla, 2006. Object-Based Image Analysis:

Strengths, weaknesses, opportunities and threats (SWOT), Proceedings

from Bridging Remote Sensing and GIS: International Symposium on

Object-based Image Analysis, 04–05 July, Salzburg, Center for Geoin-

formatics, URL:(http://www.commission4.isprs.org/obia06/ (last date

accessed: 02 December 2009).

Johansen, K., and R. Bartolo (editors), 2010. Geographic Object Based Im-

age Analysis - Special Issue, Journal of Spatial Science (in progress).

Lang. S., T. Blaschke, and E. Schöpfer (editors), 2006. Proceedings of the

1st International Conference on Object-Based Image Analysis (OBIA

2006), Salzburg University, Austria, 04–05 July, ISPRS Archieves, Vol.

No. XXXVI–4/C42ISSN 1682–1777, URL: http://www.commission4.

isprs.org/obia06/ (last date accessed: 02 December 2009).

Wiki, 2009. GEOBIA WIKI: University of Calgary, Alberta, Canada,

URL: http://wiki.ucalgary.ca/page/GEOBIA (last date accessed: 02 De-

cember 2009).

AuthorsGeoffrey J. Hay

University of Calgary

Department of Geography

2500 University Dr. NW

Calgary, AB, Canada, T2N 1N4

gjhay@ucalgary.ca

Phone: +1 (403) 220-8761

Fax: +1 (403) 2200-4768

Thomas Blaschke

Z_GIS Centre for Geoinformatics and

Department for Geography and Geology

University of Salzburg

Hellbrunner Str. 34, A-5020

Salzburg, Austria

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