Marine GIS--Where Multidimensionality Presents Special Challenges

October 13, 2003

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by Susan Smith - Managing Editor
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Message from the Editor -

Welcome to GISWeekly! A relatively new area of GIS research that is doing its part to solve some of the problems of the planet is that of marine GIS. Marine GIS plays an important role in our understanding of future environments, and in particular, of coastal communities. This week's Industry News profiles the efforts of two marine scientists who were instrumental in getting the ArcGIS Marine Data Model launched.

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Susan Smith, Managing Editor

Industry News

Marine GIS --Where Multidimensionality Presents Special Challenges

By Susan Smith

At this year's ESRI's User Conference, Jack Dangermond made the comment that the GIS-using audience was “solving all the problems in the world.” Certainly, that is a broad statement, yet the impact of each GIS researcher or professional on the planet may one day be quite significant. Being told you are solving all the problems in the world is somewhat like being told you are eating an elephant; how do you go about it? The best way, it would seem, is to break it up: maybe just eat the toes first. And that is precisely what researchers do: focus on one area of study, whether it be habitat, seafloor mapping, or global climate change.

A relatively new area of GIS research that is doing its part to solve some of the problems of the planet (and eat part of the elephant) is that of marine GIS. Marine GIS plays an important role in our understanding of future environments, and in particular, of coastal communities.

Climate change is contributing to numerous changes in the earth, and one of the most profound changes is its effect on sea level rise. Ultimately sea level rise impacts the huge population centers on the world's coasts, where most human population is concentrated. According to Joe Breman, Data Model Analyst at ESRI, if you run a search of the U.S. alone, you will come up with the top 30 counties, top 30 population centers, and the majority of them are located on the coast.

Marine GIS is a growing field. It is a field that requires a mechanism for representing great volumes of multi-dimensional data. Anyone working with marine data is well aware of the challenges faced when trying to represent multi-dimensional data from marine research. This data includes, time stamped data, height of tide and variation, temporal data and analysis, subsurface data, salinity, pressure and how those issues affect marine biodiversity.

There are some important factors that are a challenge to 3D representation of marine data today, one of them being that of 3D visualization. “Right now the 3D world of marine research for marine professionals and academics is challenged to represent 3D in computer technology,” said Breman. “There are issues of not only the 3D space as far as the location of something -- on normal maps features are represented by an x and y coordinate providing the precise location. In the ocean and coastal environments we have to deal with varying depths so we have a z representing the elevation; a minus value constantly changing with the time of day, phase of the moon, and planetary

cycle. In many cases, data

sets have sea levels that are constantly changing. Dealing with the dynamic nature of the marine data as well as the dimensionality is challenging. When we talk about time as the fourth dimension, we open the discussion to modeling based on time leading to yet another fifth dimension. As you can see, it begins to become more and more complex. Marine data usually has a temporal component of when it was collected. Data collected on the coast would be in a completely different place at 6 a.m. with a full moon, than it would be at 6 p.m. of the new moon depending on the season. So there are a lot of influences that we're only beginning to explore how to represent using computer

technology.”

Breman added that there is a 19 year planetary epoch that needs to be considered in the ebb and flow of marine data for a complete data set for some applications at the sea surface.

Birth of the Marine Data Model

Breman's background in marine archaeology brought him to Israel in 1994 to complete his MA work that completed a first application of Marine GIS for archaeology, defining port parameters and mapping a nearshore coastline using GIS. This led to pursuing work at ESRI a few years ago when the ESRI marine industry was in its infancy.

Data, data, data! For example, this is a graphic of the long-term ecosystem observatory instruments and platforms of the Rutgers U. Coastal Ocean Observation Lab

Around the same time Dawn Wright, Professor, Department of Geosciences, at Oregon State University, contacted ESRI with her idea for a marine data model initiative. “I was on sabbatical in 2001 and had some extra time to get involved in projects. So I sent an email to the ESRI folks, who agreed to host our initial working group at a workshop in October of 2001, and we were off and running. Seven of us got the data model launched. And we've had three additional developmental workshops since then,” explained Wright. This work resulted in a template data model which represents the best practices and common traits that marine scientists are implementing. “I've been working in

marine GIS since the

early 90s,” said Wright. “When ESRI started their grassroots data model initiative, it just seemed perfect to try to get a Marine Data Model started because our community had needs that could be met by such an effort. Our community, although smaller than others, now has a critical mass of people who are using GIS in the marine and coastal world. I see it as a win win situation, where, of course, people want to use GIS to help them do their applications and research better, but also GIS is being used in some different ways that helps to improve the technology.”

The ArcGIS platform was envisioned as a platform to build many industry-specific data models. The goals are to “simplify the process of implementing projects and to promote standards within our user communities.” The ArcGIS platform will continue to be built and maintained, with the thin data model extensions designed for each different scientific discipline and industry.

Why a Marine Data Model?

The ArcGIS Marine Data Model is a new approach to spatial modeling, utilizing the improved integration of ocean features and more accurate representations of location and spatial extent. More complex spatial analyses of marine and coastal data can be conducted by capturing the behavior of real world objects in a geodatabase.

Because of the persistent challenge of 3D visualization and representation in dealing with the volume of the ocean environment, rather than just looking at a 2D map, the model is expected to be able to effectively integrate marine and coastal data into 3D space and time. Currently the model includes “placeholders” designed to represent the fluidity of ocean data and processes.

Users will find that the Data Model offers a basic template for implementing GIS projects. The Marine Data Model can be used as a template for the marine data practitioner to better store, query, and analyze data for improved mapping capabilities. Ultimately, users should be able to take advantage of the advanced manipulation and analyses capabilities afforded by ArcGIS, which includes support of more complex rules that can be built into geodatabases, and objects with behavior as well as attributes.

Developers will enjoy a basic framework for writing program code and maintaining applications. The ArcGIS Data Models can also be implemented with unified modeling language (UML), an industry-standard language for designing, constructing, and documenting software architecture. “Because ESRI is supporting this effort we are creating a schema for the ArcGIS geodatabase,” Wright explained. “But working with UML allows you to develop schema for Intergraph, CARIS or any other GIS software package.”

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