Even without sophisticated WebGIS technology, it is possible to interact with maps on the Web.
Size is a very important aspect when defining hotspots. How small can a hotspot be to be distinguishable for a mouse pointer (technical limitations) or users (perceptual limitations)? This leads to the issue of sensitivity.
When a map feature is too small to be discernable, the hotspot should be enlarged. Should the distance between the border of the hotspot area and the map feature be fixed for each map feature? Should this distance be a percentage of the width of the map feature, where the width is measured perpendicular to the border of the hotspot area?
Hotspot areas in an image map cannot overlap. Each pixel on the image map can be part of only one hotspot area. This is an important issue to realise when defining hotspots to map features.
For example, there is no straightforward solution to assign one hotspot for a country and another for the main capital of the country. The hotspot area for the map feature that represents the capital would overlap the hotspot area for the map feature that represents the country. Hotspot areas must be exclusive.
In the first map, the hotspot area does not co-incide with the highlighted area. Depending on the direction from which the map feature is approached, the region is highlighted or not.
Another drawback in the first map is that the first time the mouse pointer passes over a map feature it takes long before it is highlighted. The downloading time for the images is too long. The map does not respond timely to the user's behaviour. The interaction is a-synchronous.