Monthly Archives: November 2010

Web Mapping = Web GIS ???

The question occurred to me while browsing “Mapscripting 101” over Thanksgiving whether Web Mapping and Web GIS, while people may use the terms interchangeably, are two completely different animals. Is Web Mapping for the web developer and Web GIS for the GIS developer ? Is Web Mapping simply making maps – Online Maps Light – for display on the web, while Web GIS is what … Online Maps Hardcore? Not to get too philosophical here, the two probably overlap, and may be evolving in the same general direction. Instinctively (and over simplified), I want to say that something like Mapquest or Google Maps – while only a few years ago real serious GIS – is now Web Mapping  or GIS light. Simply making a map with data but no way to query, analyze etc… I’m missing the analytical here.

I haven’t done any work with the Google API before. No telling what sophisticated work I might be able to do with it. I find that a lot of simple GIS (hack) work I do – receiving simple KML data, converting it to SHP and overlaying it with existing basemaps in ArcGIS – I could probably accomplish using the Google API and some HTML. Even my recent Mapserver efforts – sharing maps and making in-house map data accessible online – could probably be duplicated that way. I don’t know,however, how effective working with large feature sets is using KML or JSON … (note to self: look at JSON !) What I like about Mapserver is that I can use the same shapefiles I use in ArcGIS. Of course, there is much more to GIS than putting points on some basemap. So the question is: where is Web-Gis going from here ? To be continued…

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Clipping Shapefiles with OGR

How to clip shapefile to extent of another shapefile with OGR ( as found here)

Run FWTools (if you have it installed, otherwise install). Then type:

ogr2ogr -f “ESRI Shapefile” -clipsrc c:/sourcedir/sourcefile.shp c:/outputdir/outputfile.shp c:/extentfiledir/extentfile.shp

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GIS Schema…

A word I have been hearing a lot in GIS presentations lately is schema, and I admit that until recently I only had a slightly vague sense of what it stands for.

One explanation I found here when talking about the “blueprints behind GIS databases’. Well, that makes sense. Time to spend some time thinking about how to improve the schema of my borehole database.

Even better is Chapter 3 of Harmon & Anderson’s The Design and Implementation of Geographic Information Systems.

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