Technical Tips

Introduction

ArcReader vs ArcMap

Transportable Projects

Introduction

Spatial Vision has been involved in the development and maintenance of a Project GIS as part of the reclamation and sale of land at the Maribyrnong Defence Site. This has involved the collection and collation of data sourced from a number of different government organisations and project consultants in different spatial data formats. One of the challenges has been presenting this large collection of spatial datasets to project consultants in a consistent way whilst maintaining the symbology of each data custodian. ArcReader has proved a valuable tool in assisting with the dissemination of this data.

ArcReader is an ESRI product that is designed as the GIS answer to Adobe Acrobat Reader. It is free and allows for the publishing of any map that has been created in ArcMap using an extension, ArcPublisher (priced consistent with other ESRI extensions). ArcReader’s functionality is restricted to a range of basic pan/zoom/enquiry tools similar to ArcExplorer, however the full rich range of symbology and scaling options available in ArcMap is available to the published map format (.pmf) document.

back to top

The Maribyrnong Defence Site ArcReader Project

ArcReader vs ArcMap

ArcReader is essentially a stripped-down version of ArcMap, based on the ArcObjects code base. This means that any PC required to run ArcReader will need to meet the ArcGIS specification. ESRI suggests a minimum specification as being 128Mb of RAM running on a 450 MHz processor, although most users will want to have a minimum of 256Mb. In terms of operating systems, ArcReader 8.3 requires Windows NT 4.0 with Service Pack 6a, Windows 2000 or Windows XP (Home Edition or Professional). This may be limiting if you want to distribute your map to a wider audience, where the target hardware/software environment cannot be controlled. Our experience in a project involving the distribution of imagery to farmers, this constraint was critical, with many farmers running lower specification PCs. In this case, ArcExplorer proved a better alternative.

In addition, most IT departments in medium to large organisations typically bed-down their PC configuration, limiting the installation of products to users with Administrator access. Whilst Acrobat Reader is now a commonly installed application in most organisations, it may be more difficult to convince IT organisations of the need to install ArcReader, which has a minimum footprint of 63Mb. Further to this, to install ArcReader on a PC that is already running ArcGIS, you need to uninstall and re-install ArcGIS completely with the ArcReader option checked. This is can pose a major inconvenience. This aside, ArcReader represents a great option for distributing your data for ‘free’. In a number of projects where I have been involved, we have been able to package up the ArcReader application with significant volumes of data very effectively on a single CD. This allows you to present clients with an attractive web interface that provides detailed instructions on installing ArcReader, project metadata and other promotional material, along with your data. As DVD and other storage mechanisms become standard, this will further assist the ability to package up large volumes of data in this way. The free ECW plug-in to ArcReader allows you to effectively distribute compressed imagery as part of your published map format document.

back to top

Transportable Projects

When distributing an ArcReader project on CD, you need to consider from where your data will be sourced, much as you do when deploying an ArcMap project. To make your project transportable, you will need to use relative pathnames, unless your data sources will be remote SDE layers or ArcIMS map services. To enable relative pathnames, go to File > Map Properties > Data Source Options and select the “store relative path names” button. It is important to do this prior to initially saving the project (i.e. creating a .mxd file) as we have experienced issues when trying to enable “relative path names” at a later stage. When you save your data make sure you save the project to the same drive letter where you data will be stored. When you create the CD, make sure that the application is in the same position in the directory hierarchy relative to your data. This means that file based data including coverages, shapefiles and personal geodatabase layers must be stored on the same drive unless you are accessing data within an organisation via a fixed set of standard corporate drive letters. This will allow the user to copy the project data, along with the .pmf, from the CD to their hard disk, increasing performance greatly.

If you wish to implement relative pathnames as your default option I suggest customising your ‘Normal’ Template’s “NewDocument” event using the following code: Figure 1: One of the many existing buildings on site

For further information on Customising ArcMap, Ishara Kotiah has provided a Quick Insight into Customising in the Arc 8 Environment.

back to top

Another consideration when distributing .pmf documents is the storage of any images/logos that may be included on your map template. For these to be loaded correctly you need to save them as part of the project. In “Layout View” select the logo, right-click on the image, select the “Picture” tab and check the “Save Picture as Part of Document” box.

You can circumvent data storage location issues by distributing your .pmf document without the data at all, using either ArcIMS map services or SDE layers. In this way, you can publish an ArcReader Published Map Format document that draws and queries data directly from an ArcIMS map service, thereby reducing the volume of data that you distribute. Whilst this can produce some major benefits in terms of the remote production of standard maps, I suspect most organisations who have invested heavily in purchasing ArcIMS in the first place will be focussed on delivering their data via a web browser client, where there is none of the application roll-out implications of an application such as ArcReader. A .pmf document based on SDE layers may work well within a medium to large organisation depending on network bandwidth issues.

ArcReader is unlikely to become as indispensable to the GIS industry as Acrobat Reader is more generally. This is due, in part, to its reliance on proprietary vector data formats and because of the comparatively large volumes of data typically associated with GIS projects. However, the level of integration between ArcReader and the current generation of ESRI products is a major strength, and we find ArcReader represents an excellent means for providing people with an opportunity to access and interact with spatial data without the expense of purchasing a full blown GIS application.

back to top

Copyright © Spatial Vision, Monday, 14-July-2003