arcobjectsextensionsopen-source-gis
I was wondering if there are any projects based around using ArcObjects and external libraries to create open source alternatives to extensions in ArcGIS.
For example 3D Analyst, Spatial Analyst etc or even stuff like implementing some ArcInfo functionality in ArcView?
GRASS v.net.iso will give you a result like this:
You might not want to run a convex hull algorithm on this output. Imagine the blue roads: A convex hull around them would contain a lot of parts that are not reachable in the time represented by "blue".
Instead, you might want to look into alpha-shapes (related question: What are Definition, Algorithms and Practical Solutions for Concave Hull?)
You can create drive time isochrones using pgRouting and QGIS (as described here). I didn't use OSM in this case, but of course you could build your routable network based on OSM (see osm2pgrouting tool).
For a pure PostGIS solution, you can use pgRouting alpha shape function. Here is a comparison of alpha shapes as implemented in pgRouting and the approach I presented in the previous update:
Colored areas represent the results of alpha shape function, black lines are the results of the interpolation approach described earlier. The catchment areas are less detailed using pgRouting's alpha shapes. Also, there seems to be no way to vary the value of alpha to create more detailed representations.
GDAL has an ArcObjects driver and you can see the source code in SVN the tree. The Ziggis project is ArcObject's based and open source. I know they have a newer version that is also open source, but I cannot find the source location.
Otherwise, ESRI's Arcscript's site is another place to look at.
Best Answer
Most of these recommendations are not open-source, but they are free and add a lot of useful functionality to ArcMap.
Geospatial Modeling Environment - Written for ArcView (works with all licenses though), adds some functionality that is available in ArcEditor and ArcInfo. Not open-source (uses R, which is open-source though), but free.
ET Tools (GeoTools, GeoWizards, Surface) - Lots of great tools. GeoWizards adds some of the 3D Analysis functionality. Again, not open-source, but lots of free tools available before you have to pay.
ArcScripts - Discontinued, but still an extensive archive of scripts contributed by users. All are free. Most of the scripts are pre version 10, but since you have access to the source code, you could port them over.
ArcGIS Code Gallery - New version of ArcScripts