C.1 Limitations of this tool
ArcMap is able to perform analytical tasks on large volumes of data, but when compared to the latest developments in the mobile GI field using it to create a mobile directory seems like overkill.
Mobility is restricted as it operates on static datasets whilst requiring a client with significant processing capacity and an external server offering interaction and presentation GI services.
Using reverse-geocoding the tool is able to perform spatial queries depending on post-code information, however with each post-code indentifying between 1 and 100 unique addresses, the accuracy level of the spatial query performed is depended on the type of location clicked on the map (street numbers on larger roads usually have longer distance between them). In addition, the search tolerance setting on the ArcMap document, used within the VB script1 will influence heavily the post-code returned.
C.2 Is Google Local thorough in identifying available services? How about searching information other than 'services'; What type of limitations exist in querying spatial information in generally?
Google Local is a location-based service, accessible via thin client architecture. It allows querying by specifying various spatial search criteria and is supported by services2 responsible to convert the textual descriptions to spatial coordinates. However, with queries containing evaluative criteria such as ‘which is the best restaurants in Leytonstone’, the results span all over across London; the user needs to pan the map or filter based on distance to focus in the area preferred. When the term ‘best’, was replaced with ‘cheapest’, irrelevant results regarding property maintenance services were returned. More ambiguous qualitative queries like ‘the most expensive street in London’ did not return relevant results. It is understood that such a complex process of extracting semantically correct meaning out of verbose queries spans in many different scientific research fields, including linguistics, AI etc, therefore such inconsistencies in the results must be within the user’s expectations. But is apparent that the work that has been invested in such a tool has yield in a extremely efficient service with lots of options, which it can only be further improved.
C.3 Would a search of all Internet resources provide further information; What alternatives are there to using a postcode for spatial queries;
Extending the search using a search engine yields many results with potentially exact and relevant information; however there are fundamental differences in the algorithms behind search engines with those behind GI directory services which suffer from the lack of universally agreed geography type; An attempt to tackle this problem is provided by the GeoXwalk3 project: geometric computations introduce a mechanism to resolve spatially complex queries4 describing relationships between features with complex geographic boundaries. Further development has been done to enable advanced querying5 by “explicitly georeference implicitly georeferenced material” (geoXwalk Phase III - Final Report, 2004) .
C.4 Availability in other regions and countries
According to Google(6), there is an ongoing process on making this service available everywhere in the world, but this is not the case yet; though a workaround exists by creating a public My Map to list any business information which then can be searched using Google Maps7.
C.5 References
1. ‘ get the postcode
Dim postcode As String
postcode = getPostcode(pMxDoc.SearchTolerance, pPoint, pMxDoc.FocusMap)
2. Such as gateway location services, directory services, geocode services, route determination services etc.
3. Reid, James & Medyckyj-Scott, David., 2004. GeoXwalk Phase III – Final Report. Available at: http://edina.ac.uk/projects/geoxwalk/documents/geoXwalk%20Phase%20III%20Final%20report.doc[Accessed April 12, 2010].
4. i.e. ‘which rivers are near Banbury? ’ (geoXwalk Phase III – Final Report, 2004)
5. i.e. ‘find me all documents about Gaelic songs that do not reference the Western Isles or, find me images of towns along the river Tweed’ (geoXwalk Phase III – Final Report, 2004)
6. Maps features available in your country – Maps Help. Available at: http://maps.google.com/support/bin/answer.py?hl=en&answer=16634 [Accessed April 12, 2010].
7. http://www.google.com/support/forum/p/maps/thread?tid=7f1a2dcf8c70f97c&hl=en
