PASDA GIS Data Reminder

As the Oil and Gas boom has hit Pennsylvania, GIS data is a prime commodity in obtaining permits and generating needed concept plans. A major source is the Pennsylvania Spatial Data Access (PASDA) clearinghouse. And I quote:

Pennsylvania Spatial Data Access (PASDA) is the official public access geospatial information clearinghouse for the Commonwealth of Pennsylvania and has served for fifteen years as Pennsylvania’s node on the National Spatial Data Infrastructure, Geospatial One-Stop, and the National Biological Information Infrastructure.
PASDA was developed by the Pennsylvania State University as a service to the citizens, governments, and businesses of the Commonwealth. PASDA is a cooperative project of the Governor’s Office of Administration, Office for Information Technology, Geospatial Technologies Office and the Penn State Institutes of Energy and the Environment of the Pennsylvania State University. Funding and support is provided by the Pennsylvania Office for Information Technology,Geospatial Technologies Office. In addition, PASDA also receives substantial support from the Pennsylvania State University.

So there are tons of great data types to choose from, depending on your needs. But there is one question I often get asked and rarely remember the answer. For some reason, some data is formatted to be in the coordinate zone Antarctic98.LL, which refers to the Lat Long grid for the Australian Antarctic 1998 datum. Of course, this is not correct. So the first place to research is the metadata.

Map 3D 2009 is Citrix Certified

When I saw this bit of news recently, I presumed I was dreaming.  If you don’t know, Autodesk has not supported any of its products in a hosted environment, be it Terminal Services or Citrix based.  Additionally, if you read the EULA, you might even be breaking that agreement as well. Why does this matter?

Map 3D Topologies – Part 2: Overlay Analysis Results

Nathan Moore from Autodesk helped resolve yesterday’s post.  Apparently, overlay analysis of topologies changes arcs into a series of line segments, this was in our example.  Here’s the kicker – it cuts the circle represented by the arc into 32 segments that match into the endpoints of the arc. 

He agreed that this can cause errors in area, networks, etc. which are generally small in the GIS world who looks at things at a grand scale.  But when used for Engineering purposes, this error is no longer negligible.  So he created what he called a “Change Request” to have developers address the issue.

So what do we do now?  Any topologies you may create should only have line segments. If you have arcs, convert them to polylines and have the DRAWING CLEANUP tool weed the arc as needed.  That way, you’ll at least match areas when comparing base topologies to overlay analysis topologies.

Map 3D Topologies – Part 1: Curves are not really curves?

OK, so what am talking about?  First, lets define a few things.  Map 3D can build a topology; which is a generic GIS term for polygon shapes. These shapes can contain curves.  You ask yourself – But you said they’re not really curves? I know. I know.  Read on for the details….