web cartography

Introduction

In October 2000 I received a Master of Arts degree in Human Geography from Utrecht University. As my major was in the field of Cartography and I have a strong interest in GIS and the Internet, my thesis covers the overlap between these three areas:

Is current commercially available WebGIS software adequate to generate web maps for webmapping applications that facilitate the visual use of geospatial data sets across the World Wide Web?

With the digital revolution in cartography during the 1980s, geo-processing became separated from geospatial database creation and -management. In networkedcomputer environments this is even more so: WebGIS software facilitates the functionality of a GIS to be distributed across the WWW. The web maps generated by WebGIS, have become the interface between the client and the service of the WWW-based Geospatial Data Infrastructure.

Cartographers have to consider new issues in designing and constructing web maps and developing webmapping applications:

Benchmarking

Benchmarking is a practical test for a system (hardware or software) to test the operational use for a specific application. In this thesis, the benchmark test is formulated based on the description of a WebGIS software package that perfectly generates web maps. These web maps facilitate the use of geospatial data sets across the Web perfectly while taking into account both the characteristics of the Web as a visualisation environment for cartography and the different types of web map use.

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Title page, foreword, toc, introduction (PDF, 124.16KB).

Chapter 2 + 3 (PDF, 61.77KB).
Chapter 2 forms the scientific background for this research. Furthermore, it introduces the theory to structure the types of map use that have to be taken into account while designing maps. These types of map use are further elaborated upon in chapter four. The third chapter provides an extensive literature review addressing the characteristics of the Web as a visualisation environment for cartography.
Chapter 4 + 5 (PDF, 163.69KB).
Introduced in chapter two, the theory structuring map use is described further in chapter four. This theory is then adjusted to the context of the Web, so the theory can be applied to types of web map use. Chapters three and four describe thus the conditions that have to be taken into account while designing web maps. Based on the answers to these sub-questions the benchmark test can be constructed. In chapter five, the attention is once more drawn to the mapping constraints. Then, structured by the mapping constraints, two ideal webmapping applications are described. These descriptions serve as a substitute for a formal User Requirements Analysis (URA) that usually is the input for constructing a benchmark problem. Based on these descriptions, the benchmark test is constructed by designing some webmapping problems to be solved by the selected WebGIS software programmes.
Chapter 6 + 7 (PDF, 178.89KB).
In chapter six these WebGIS software packages are evaluated by comparison of their problem-solving performance with that of the "benchmark". In the final chapter, this comparison is evaluated so that conclusions can be drawn and recommendations can be made to further scientific research and to facilitate the choice webmapping application developers and web cartographers have to make to select the best WebGIS software package fulfilling their webmapping requirements.

Appendices (PDF, 166.52KB).

Bibliography (PDF, 18.70KB).

web-safe colours

For displaying colour web browsers use colour look-up tables, drawing from the internal colour palettes of the different platforms. Although colour palettes of PCs and Macs are different, they have 216 colours in common. To allow for cross-platform differences and to still be able to control the correct colour perception at the client-side, only colours from this web-safe colour palette should be chosen.

In ArcView GIS, the colour palette does not distinguish web-safe colours. To be sure that only web-safe colours are used at the design stage, an ArcView colour palette has been generated using the "colour-picker" plug-in:

math (AVP, 139.89KB)
The organisation by math puts these colours in order of their respective values for RGB

Since this web-safe colour palette was generated by math, not visual insightfulness, it has been re-arranged so it might make sense to visual designers and cartographers. There are two versions here: one organised by hue (for use on chorochromatic web maps) and one organised by value (for use on choropleth maps). Note: These two palettes have identical colours as the previous one, they are simply organised differently.

hue (AVP, 139.89KB)
The organisation by hue puts these colours in order by colour.
value (AVP, 76.03KB)
The organisation by value puts these colours in order of light, middle values and darks

This web-safe colour palette should be used together with the GIF output option available in ArcView IMS. The "lossy" JPEG compression does not maintain the colour palette resulting in dithering.

Post Scriptum

After I finished writing my thesis in May 2000, newer versions of the software packages I benchmarked have been released and more GIS vendors have released their own WebGIS software. For an overview of the state of the art in WebGIS, you may want to read Fred Limp's “User Needs Drive Web Mapping Product Selection”. This article was published in GeoEurope, March 2001.

In “Internet GIS: Distributed Geographic Information Services for the Internet and Wireless Networks”, authored by Dr. Zhong-Ren Peng and Dr. Ming-Hsiang Tsou, the latest evaluation of commercial webmapping programmes is presented.