A CD-ROM Entitled, "GIS Data of the Monterey Bay, California: A Lesson in the A,B,C s of Dissemination

Transcription

1 A CD-ROM Entitled, "GIS Data of the Monterey Bay, California: A Lesson in the A,B,C s of Dissemination Randolph Bucciarelli, California State University, Monterey Bay Mentors: Gerry Hatcher, Norm Maher Summer 1998 Keywords: GIS, CD-ROM, Monterey Canyon Abstract At the Monterey Bay Aquarium Research Institute (MBARI), a large portion of the Mission Statement is the dissemination of data and information amongst the general scientific and educational communities. Towards that goal we have created the CD-ROM entitled, "GIS Data of the Monterey Bay, California" which is a compilation of oceanographic and related GIS data of the Monterey Bay region. The data set is intended for the creation of base maps to be implemented in marine-related research and education, not for commercial profit. In an attempt to make this CD accessible to as many individuals/institutions as possible, much of the data have been converted to a format readable by the Environmental Systems Research Institute s (ESRI) software ArcView, ARC/INFO, and ArcExplorer. Several files compatible with other software programs, such as the Generic Mapping Tools, have been included as well. Introduction The CD-ROM is a documented compilation of oceanographic and related GIS data of the Monterey Bay region. It was produced at the Monterey Bay Aquarium Research Institute during the summer of Members of a "CD-ROM team" - Gerry Hatcher, Norman Maher, Nancy Barr, Dave Coleman, and Randy Bucciarelli - all contributed to the final product. The primary use of this data set is intended to provide the layers necessary for the creation of base maps to assist in marine-related research and education. When placed in a map, these layers such as a coastline, shaded imagery, and bathymetry provide the viewer with a spatial reference and allow other data to be put into its intended context. In choosing a format to distribute the data, we had hoped to produce a stand-alone (not requiring any miscellaneous software) package that was accessible via the Mac, PC, and UNIX computer platforms. However, due to the relatively young age of GIS technology, we were forced to compromise and appeal to the needs of the greatest number of prospective users. The format incorporated by the Environmental (1 of 11) [11/3/ :17:59 AM]

2 Systems Research Institute (ESRI) was chosen on the basis of its availability and widespread use. ArcView has become the industry standard for desktop (small scale) GIS and is also available on the three target platforms for the CD. ARC/INFO is a high-end GIS software that was used in producing, converting, and managing much of data on the disk. Currently the data browser, ArcExplorer (version 1.1), included on the CD-ROM is only available for machines running Microsoft s Windows 95 or Windows NT. We chose ArcExplorer, a product of ESRI, due to its functionality, easy-to-use interface, and its ability to be distributed with the data set at no cost to the users or MBARI (downloaded from ). For those users without access to ESRI software we have included files formatted for the Generic Mapping Tools (GMT) public domain software ( {NOTE: used to be available at GMT that has been described as "an unofficial standard" among geo-scientists and it is used widely for the purposes of making maps comprised of data similar in nature to the "base map" layers found within "GIS Data of the Monterey Bay, California" (Wright 1998). Finally, we included bathymetry data formatted as ASCII text files (made up of tab delimited x, y, and z values that correspond to longitude, latitude, and depth), which are compatible with most software packages. GIS In General A geographic information system (GIS) can be described as a system of software, hardware, and individuals that deal specifically with the spatial relationship of an object (canyon, mountain, tree, car, building, river) to its surroundings. When studying this object, the GIS system assists in the collection, storage, conversion/manipulation, analysis, and display/presentation of the data object s spatial attributes (Star and Estes 1990; Paris and Associates 1996). GIS was used in the creation of the CDROM specifically as a tool to form, manipulate, manage, and present all the data layers found within its contents. GIS technology is unique because of its ability to incorporate data objects as individual layers each related by their spatial distribution. A layer (or "theme" as referred to by ESRI) has the ability to overlay and be used in the display, analysis, or modeling process. The layers found within the CD s contents take the form of either feature (vector data), image, or grid (raster) data. Feature objects are made up of point, line, or polygon elements. Each individual object, or "shapefile," has attached database records specific to the type of data the file is used to represent. For example, the contour lines feature data included on the CD-ROM have attached location information and the depth value at each contour interval. When displayed in a GIS software program such as ArcExplorer, the user can manipulate the file s database and display the data according to his/her needs. Images displayed in an image-processing program (i.e. Photoshop) are referenced using an "image" coordinate system consisting of rows and columns. Before the image can be included as a functional layer within a GIS, the rows and columns of an image must be associated with geographical, or "map," coordinates (x,y or lat,long). The conversion between image and map coordinates is termed georeferencing, or registration (ESRI 1991, Paris and Associates 1996). This transformation is accessed every time the image (i.e. TIFF format) is called upon by the user to be displayed. A "world" file (i.e ".tfw") is the source for this and contains parameters such as the cell (or pixel) size, rotation factors, and a pair of coordinates that ensure the image s proper registration with other objects in the GIS (ESRI (2 of 11) [11/3/ :17:59 AM]

3 1991). Grids are used to describe a variable (i.e. elevation or temperature) that changes spatially or temporally within a GIS. Grid themes are made up of matrices of square cells, where each set of cells are assigned both spatially referenced coordinates (i.e. latitude and longitude) and a value (i.e. z values assigned to heights or depths), dependent upon the nature of the variable being represented (ESRI 1998). A grid can represent continuous or discrete data, at a variety of scales and resolutions. If the cell size is small (a large number of cells per unit area) the data is considered to be high-resolution and the grid will show more detail. The opposite is true of a larger cell size where the grid is of a low-resolution. However, depending upon the nature of the data, more detail may not necessarily be a better choice. An exponential relationship exists between the cell size, or resolution, of a grid and its file size. Therefore several tradeoffs exist in choosing to use a smaller cell size. High-resolution data are computationally intensive and require tremendous amounts of disk space, often exceeding the physical limitations of both the CD-ROM and the computer system. Within the "grids" directory are several bathymetry files with corresponding hillshades. The hillshades may help an individual to visualize the data by illuminating a surface and creating a shadowing effect thereby bringing out the relief in a variable surface (see Figures 1 and 2). The grid themes have cells that are often assigned a color based upon the cell value (i.e. z values representing elevation). These values are often shown in a legend and can be altered to fit the user s need. Map Datum and Projection In order to display a given scanned map or image (displayed on a screen or paper), it is necessary to transform the 3-dimensional space that we are used to seeing, (i.e. when submerging into a canyon or scaling a mountainside) to a flat 2-dimensional representation of that reality. The characteristics, such as the area or shape covered, resulting from mathematically warping a spherical section of the earth onto a flat surface is termed a projection. There are several projections depending upon the type and specific location of data being used (Star and Estes 1990). All of the data within the CD-ROM were registered to the WGS84 horizontal datum and projected into both the Geographic coordinate system and Universal Transverse Mercator (UTM) Zone 10 projection. To ensure their use as functional layers within a GIS, all of the data were checked for datum and coordinate system correctness. Methods Gerry Hatcher and Norman Maher had completed a bulk of the CD-ROM s content a year prior for internal distribution. However several steps were required in order for the CD to be ready for distribution outside of MBARI. The methods employed in compiling the CD-ROM, "GIS Data of the Monterey Bay, California," were divided into three main tasks. Data Organization and Standardization The first step in creating "GIS Data of the Monterey Bay, California," was to define a prospective audience. This set the stage for the rest of the project because it gave its creators a measure of what type of systems/individuals would be using the data. We chose to focus our efforts in providing the CD for the marine-related educational and research communities as this is a focus of the MBARI Mission Statement. For our purposes we assumed that the average student/researcher did not have the ideal resources (i.e. (3 of 11) [11/3/ :17:59 AM]

4 high-end software/hardware) to run what was already on the disk. Therefore, based on this, the following items needed to be included as "add-ons" for the CD to be of use to the majority of the intended audience: A data interface tool for the purposes of viewing and assembling maps with the various data layers. An html document intended to be used as an index to all the documentation layers. TIFF formatted shaded imagery reflecting the contents of the "grids" directory. Two versions of each data layer; one in a Geographic coordinate system (decimal degrees) and the other in a Universal Transverse Mercator (UTM) projection (zone 10). This was done to make the CD-ROM of use to a variety of different data sources. Changing between coordinate systems is computationally intensive often requiring high-end software (i.e. ARC/INFO) and hardware systems. GMT and ASCII text files reflecting the contents of the "grids" directory. A "ReadMe.txt" file. New documentation files for every additional data layer. Throughout the organization and standardization process, every layer was uniformly named, formatted, and described. The documentation process involved standardizing existing data descriptions and creating new text files for any added data layers. All of the documentation layers were formatted as ASCII text (.txt) in order to be read by all three target platforms (MAC, PC, and UNIX). The text files were edited by several members of the CD-ROM team and revised several times. This proved as one of the most time consuming factors throughout the project. Content Creation/Gathering Data conversion is often one of the most computationally intensive processes when dealing within a GIS. Table 1 is a list of sample data conversion processes employed in the production of the CD-ROM. Input Conversion Description Process Output Bathy200 ARC/INFO Grid to GMT Grid Done in ARC/INFO ArcGMT Tool Bathy200.gmt Bathy20f Bathy200 ARC/INFO Grid to ASCII text Done in ArcView Export Option Bathy20.asc Bathy200.asc ARC/INFO Grids Name change of ARC/INFO Grids Done in ArcView Spatial Analyst Manage Grids Option See "Grids" directory under Results GEO->UTM Projection Change ARC/INFO Project Command Alternate of Input UTM->GEO ARC/INFO Grid ARC/INFO Grid to TIFF shaded imagery ArcView ArcPress extension TIFF shaded image (unregistered) (4 of 11) [11/3/ :17:59 AM]

5 TIFF Image Registration/ Rectification of shaded Image Done in ARC/INFO Register and Rectify commands. Result in a "world file." (.tfw) TIFF image with accompanying ".tfw" file. Table 1. Sample Data Conversion Processes Users without the ArcView Spatial Analyst extension or ARC/INFO software (including ArcExplorer users) are unable to display the grid data on the disk. Therefore, some of the key grids were converted to TIFF formatted shaded imagery which is compatible with most GIS and image processing software. Other data conversion took place in ArcView and ARC/INFO, specifically the conversion to GMT (using the ArcGMT tool acquired at the following URL, and ASCII tab delimited text formats. Several of the data layers had been acquired outside of MBARI. These data required permissions from their sources in order for their inclusion within the CD-ROM. It was necessary to include copyright information that released the liability of these sources and MBARI itself. Production The actual process of writing the CD itself, meant becoming familiar with the hardware and software associated with the process. To reach a multitude of computer platforms and users, the ISO-9660 naming convention was used. This limited the titles of all items on the CD-ROM to eight characters or less. The CD required multiple test prints to ensure it was completely debugged and all the data were usable. A thorough testing process was done to ensure proper usage of the data and documentation files on these systems. A user-friendly/clean directory structure was necessary to organize the data onto a hard disk. In producing a CD for distribution into the scientific and educational communities, where a variety of computer platforms are found, it was necessary to thoroughly check each data/documentation layer for compatibility and accuracy. The team decided based on cost efficiency and ease of use to provide the CD-ROM within a cardboard jacket. The cover design and text were then designed and implemented onto the jacket itself. The text on the cover of the jacket is important to the user because it provides a quick reference and conveys what type of information is held within the disk. Based on the projected demand within the CD s target audience, an order for 500 hundred copies to be initially printed was made. Web pages were designed to describe the CD-ROM s contents and contact information. A CD-ROM address (cdrom@mbari.org) was also created in order to avoid complications with ordering requests and technical questions involving the disk s contents. Results The CD-ROM is a convenient and cost-efficient means of distributing a large amount of digital information to a widespread audience. The disk resulting from the CD-ROM Team s efforts is hoped to be an easy-to-use compilation of marine-related GIS data for the Monterey Bay region. The disk s contents are shown in Table 2. (5 of 11) [11/3/ :17:59 AM]

6 200mcont.shp 100mcont.shp Geo 10m_cont.shp dnc_appr.shp dnc_harb.shp faults.shp landmask.shp Features moorings.shp Data/Docs (6 of 11) [11/3/ :17:59 AM]

7 200mcont.shp 100mcont.shp UTM 10m_cont.shp dnc_appr.shp dnc_harb.shp faults.shp landmask.shp moorings.shp Grids Bathy200.grd GMT Features 100mcont.gmt dnc_appr.gmt dnc_harb.gmt landmask.gmt bathy200 bathy20 bathy20f hshd200 Geo hshd20 hshd20f Grids hshd_dem mont_dem (7 of 11) [11/3/ :17:59 AM]

8 bathy200 bathy20 UTM bathy20f hshd200 hshd20 hshd20f hshd_dem mont_dem c18685.tif dem_sea.tif geology.tif Geo gryshade.tif landsat.tif mb50sat.tif mb50slar.tif topo_map.tif Images sidescan.tif sseast.tif c18685.tif dem_sea.tif geology.tif UTM gryshade.tif landsat.tif mb50sat.tif mb50slar.tif topo_map.tif sidescan.tif sseast.tif (8 of 11) [11/3/ :17:59 AM]

9 ASCII bathy200.asc bathy20f.zip Misc colormap.avl Table 2. CD-ROM Contents A "ReadMe_1.txt" file was created to provide the end user with the information/instructions/guidelines to get started working with the disk. Included within this file are the following (see attached ReadMe_1.txt for full document): -- SUMMARY -- NOTE -- SYSTEM REQUIREMENTS -- GENERAL -- ARCEXPLORER -- ARCEXPLORER 1.1 INSTALLATION -- USER INFORMATION -- PC USERS -- WITHOUT ARCVIEW OR SPATIAL ANALYST EXTENSION -- WITH ARCVIEW SPATIAL ANALYST OR ARC/INFO -- MAC USERS -- UNIX USERS -- CD CONTENT -- CONTACT INFORMATION -- MBARI DISCLAIMER -- NIMA DISCLAIMER The data layers included on the disk will be of value to educators, students, and researchers for a variety of uses. Potential applications of this data include use in "fly-through" software (i.e. VRML and Fledermaus. Please see the following website for an example: or in the production of images that may be included on posters, maps, slides for use in publications, presentations, and various other projects. Conclusions/Recommendations As of this writing, "GIS Data of the Monterey Bay" has not been sent to the printer for reproduction. The creators are still in the process of completing portions of the Production phase described above. In disseminating information outside of MBARI, it is important that the product be flawless. In lieu of this, (9 of 11) [11/3/ :17:59 AM]

10 the CD-ROM team are reviewing and improving both the external appearance (i.e. cover and jacket design) and internal contents. It is difficult to gauge the amount of time any one task takes to complete in its entirety. Overestimating rather than underestimating the time and effort required in a project such as this is a critical first step. This is of importance particularly when dealing with deadlines and other individuals/institutions (i.e. for permissions and copyright information). Working in a team, where each individual contributes their expertise is invaluable to the eventual finished product. Effective communication among team members is essential to avoid duplication of effort and to efficiently distribute the tasks at hand. Meeting regularly helped the group gauge the progress and eventual completion of "GIS Data of the Monterey Bay." In regards to recommendations for future reference, the majority of the time spent was in the production phase. Acquiring permissions, testing of the CD, uniformity of data/docs, cover design all took large amounts of time to complete. Many of these tasks should be ongoing from the start and not left until the last minute. This minimizes the time spent on them in the latter portions of the project where time may be of the essence. Also of note was the attempt in reaching a multitude of platforms and end users. It was difficult to make sacrifices on the quality or quantity of data in order to be of use to the greatest number of users. The possibility of creating GIS-software specific to MBARI s needs is possible given the scope of talent found here. Acknowledgements I learned a tremendous amount in a very short time, I can only hope that one day I will be able to pass it on in the same way it was given to me. A huge amount of thanks to Gerry Hatcher and Norm Maher for putting up with my never-ending barrage of questions this summer. Nancy Barr and Dave Coleman always had positive feedback on the project this summer. I had the opportunity to work with them both quite a bit this summer and consider them my mentors as well Thanks to both of you!!! George Matsumoto was truly an inspiration to me because he showed me the way to have fun and learn at the same time. For all the time he put into the internship program he deserves a medal Thank You George. I am much obliged to the Video Lab crew for all of their assistance. Kyra, Kris, and Nancy were always there to help no matter how much work they had thank you so much. References Hatcher, G. A., Maher, N.M. and Orange, D.L. (1997) The customization of ArcView as a real-time tool for oceanographic research. Proceedings of the 17 th Annual ESRI User Conference. San Diego, CA. Paper (10 of 11) [11/3/ :17:59 AM]

11 Image integration: incorporating images into your GIS (1991). In: ARC/INFO 6.0 user s guide. Environmental Systems Research Institute, Inc., Redlands, CA. Paris & Associates/Atterbury Consultants, Inc. (1996). The ABCs of TNTmips Version 5.4. Star, J. and Estes, J. (1990). Geographic information systems; an introduction. Prentice Hall, Englewood Cliffs, N.J., 503 pages. The goods on grids (1998). In: Working with ArcView Spatial Analyst. Environmental Systems Research Institute, Inc., Redlands, CA. Wright, D.J.. Wood, R. Sylvander. B. ArcGMT: A suite of tools for conversion between Arc/INFO and Generic Mapping Tools (GMT). Computers and Geosciences. In press Wright, D.J., Rumblings on the ocean floor: GIS supports deepsea research, Geo Info Systems, 6(1): 22-29, (11 of 11) [11/3/ :17:59 AM]