Dr Mike J Smith

Plymouth University

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Area is a standard geometrical property right?

Tue, 20 Mar 2007

Well you would have thought so wouldn't you? We have the following simple geometry:

points: they have a location (x,y)
lines: they have a location based upon a start and end point, in addition the have the properties of length and orientation
polygon: they have a location based upon coordinates of the points making up the feature, and also have properties that include a centroid, area and perimeter. There are also other things you might want to calculate including min/max dimensions, maximum bounding box etc

So thats straightforward. OK, so if you want the basic properties you would expect your GIS to be able to calculate at least most of the "basic" properties "out of the box". Lets take ArcGIS 9.1 as an example:

points: well it must be able to record the point otherwise you wouldn't be able to see it. Can you get the coordinate? No.
lines: Ditto, so we can't get the start/end points. Orientation. No. Length. Errrr. No.
polygon: Ditto for points again. Perimeter. No. Area (and, I might add, one of THE original reasons that a GIS preferred to manual calculations). Errr. No.

Well its not strictly correct. All of the above features can be extracted in ArcMap using some good 'ole VBA code. Now thats nice and easy (not!). Some of them can be extracted using ArcToolBox. Ah, you need the underlying ARC/INFO and, more importantly, the more expensive license for it. The points can also be extracted by exporting in an ASCII format although, yes, you need ArcToolBox. What started all this off? A student asking if they could calculate area as surely that must be easy! No wonder there is an over-proliferation of add-ons like ET Tools, XTools Pro and Hawths Tools. I know ESRI can't program everything; BUT REALLY. This is elementary geometry.

So am I getting increasingly frustrated with ESRI's banal minimalist interface that fails to give you easy access to the fundamental underlying geometry? Yes. The now outdated and poorly designed interface that is littered with toolbars, many of which you have to pay for the functionality? Yes. The over-reliance on ArcToolBox to access functionality in the well documented and programmed ARC/INFO that they couldn't be bothered/have time to re-write properly? Yes. The over-proliferation of tools in ArcToolBox under strange group headings, with different groups having the same tool name that does different things (e.g. Project, Buffer). Yes. The bungling in-out mentality with the GeoProcessing Wizard (in in 8.x, out but turn on-nable in 9.0, removed in 9.1 to be replaced with a pathetic help screen, in as a download in 9.2). Yes. Please make up your mind!! Either make the ArcToolBox tools easy to use or write the GeoProcessing Wizard properly.

Rant over and I no doubt stand to be corrected on several things!

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