Jump to content

 
Photo

shapefiles...the de facto standard?

- - - - -

  • Please log in to reply
18 replies to this topic

#16
pfyfield

pfyfield

    Master Contributor

  • Validated Member
  • PipPipPipPip
  • 100 posts
  • Gender:Male
  • Location:Portland, Oregon
  • United States

I use shapefiles, coverages, personal geodatabases, file geodatabases and sde geodatabases. Typically I export a shapefile for import with MAPublisher.
One drawback- shapefiles, like geodatabases, use the polygon list data model. Shared boundaries between polygons result in coincident linework, which is potentially an issue with dashed symbology. Easy to fix, but sometimes an extra step.
Paul Fyfield
Cartographer, Bureau of Land Management
Oregon State Office
Portland, Oregon
pfyfield@blm.gov

#17
David T

David T

    GIS Manager, USMC, MCIWEST-MCB Camp Pendleton

  • Validated Member
  • PipPipPipPip
  • 192 posts
  • Gender:Male
  • Location:San Diego, California
  • United States

For example, if I know that my client has THE SAME version of ArcGIS as I do (remember, gdb's are NOT backwards compatible... i learned this the hard way :angry: )


There are ways around that. ;)

Actually, there are sneaky ways around that - going into Access and changing a couple of field values, and there are legitimate ways around that. Sometimes, it's useful to keep a couple of different versions of PGDBs around - I have 8.1, 8.2, 8.3, 9.0, and 9.1 compatible empty PGDBs around, just in case that sort of thing happens. You can do a lot of quick copying and pasting. Of course, if there are things that are specific to one version of a PGDB that cannot be copied backwards, then you'll have some problems. But the basics are compatible all the way around.

One drawback- shapefiles, like geodatabases, use the polygon list data model. Shared boundaries between polygons result in coincident linework, which is potentially an issue with dashed symbology. Easy to fix, but sometimes an extra step.


From a cartographic standpoint, this is *highly* annoying. It helps at ArcGIS 9.2, with the cartographic tools. But, many an hour has been spent taking a polygon dataset and creating a line dataset out of it, and then editing that linework to eliminate the coincident linework. It's a pain, but, sometime therapeutic (it's easy to get 'lost' doing that work, and not thinking about anything else).

During the October 2007 fires in San Diego County, data was being distributed from different agencies via shapefile. And while it was the quickest way to get data around, as it's been mentioned earlier in thread, there is no topology as a part of that data. We had to spend some time massaging our data to get into our SDE. Cleaning up polygons (over and undershoots, etc) took some time. If the data had been developed in an PGDB, some of those issues would have been solved. Of course, the point was to get the data out there as quickly as possible, too. (We're talking about fire perimeters, current hot spots, road closures, etc).
David Toney, GISP
GIS Manager
United States Marine Corps
West Coast Installations

#18
chris thompson

chris thompson

    Newbie

  • Validated Member
  • Pip
  • 4 posts
  • United States

Sadly the bit about shapefiles 'usually' having associated .prj files is not so much a problem with the format, as it is with sloppy GIS practices. All it takes to get a .prj file attached to a shapefile it to do a projection definition. I have been stunned over the years at how often this simple step has been skipped or overlooked. I even had a GIS manager once who would not let us define projections, and would make us embed the projection information into shapefile names.

#19
frax

frax

    Hall of Fame

  • Associate Admin
  • PipPipPipPipPipPipPip
  • 2,299 posts
  • Gender:Male
  • Location:Stockholm, Sweden
  • Interests:music, hiking, friends, nature, photography, traveling. and maps!
  • Sweden

Something that annoys the hell out of me is when shapefiles are packed up from being managed by ArcCatalog, and they include a metadata file (xml) - but with no real information, just the default placeholders "REQUIRED: this field should bla bla". If you can't bother to write up the metadata, don't include the file!
Hugo Ahlenius
Nordpil - custom maps and GIS
http://nordpil.com/
Twitter




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

-->