GIS Data Formats and My Stubborn Opinons

Taking this break I’ve been looking over my spatial data and trying to figure out how to best organize it. The largest public project I manage is the GeoJSON Ballparks and this one is easy to manage as it is just a Git repository with text files. GeoJSON makes sense here because it is a very simple dataset (x/y) and it has been used for mapping projects mostly which makes the GeoJSON format perfect. I used to maintain a Shapefile version of it in that repository but nobody ever downloaded it so I just killed it eventually.

But my other data projects, things I’ve mapped or worked on the past are in a couple of formats:


  • Shapefile
  • File Geodatabase
  • Personal Geodatabase
  • GeoJSON
  • KML
  • SpatiaLite


  • TIFF (mostly GeoTIFF)
  • Esri Grid

Now you can tell from some of these formats, I haven’t touched these datasets in a long time. Being Mac centric, the Personal Geodatabase is dead to me and given the modification dates on that stuff is 2005-2007 I doubt I’ll need it anytime soon. But it does bring of the question of archival, clearly PGDB isn’t the best format for this and I probably should convert it soon to some other format. Bill Dollins would tell me GeoPackage would be the best as Shapefile would cause me to lose data given limits of DBF, but I’m not a big fan of the format mostly because I’ve never needed to use it. Moving the data to GeoJSON would be good because who doesn’t like text formats, but GeoJSON doesn’t handle curves and while it might be fine for the Personal Geodatabase data, it doesn’t make a ton of sense for more complex data.

This is as close to a shapefile icon as I could find, tells you everything doesn’t it?

I’ve thought about WKT as an archival format (specifically WKB) which might make sense for me given the great WKT/WKB support in databases. But again, could I be just making my life harder than it needs to be just to not use the GeoPackage? But there is something about WKT/WKB that makes me comfortable for storing data for a long time given the long term support of the standard among so many of those databases. The practical method might be everything in GeoJSON except curves and those can get into WKT/WKB.

Raster is much easier given most of that data is in two fairly open formats. GeoTIFF or TIFF probably will be around longer than you or I and Esri grid formats have been well support through the years making both fairly safe. What are some limits to data formats that I do worry about?

  1. File size, do they have limits to how large they can be (e.g. TIFF and 32-bit limit)
  2. File structure, do they have limits to what can be stored (e.g. GeoJSON and curves)
  3. File format issues (e.g. everything about the Shapefile and dbf)
  4. OS centric formats (PGDB working only on Windows)

I think the two biggest fears of mine are the last two, because the first to can be mitigated fairly easily. My plan is the following; convert all vector data into GeoJSON, except where curves are required, I’m punting curves right now because I only have 3 datasets that require them and I’ll leave them in their native formats for now. The raster data is fine, TIFF and grid is perfect and I won’t be touching them at all. The other thing I’m doing is documenting the projects and data so that future James (or whomever gets this hard drive eventually) knows what the data is and how it was used. So little of what I have has any documentation, at least I’m lucky enough the file names make sense and the PDFs help me understand what the layers are used for.

One thing I’ve ignored through this, what to do with those MXDs that I cannot open at all? While I do have PDF versions of those MXDs, I have no tool to open them on Mac and even if I could, the pathing is probably a mess anyway. It bring up the point that the hardest thing to archive is cartography, especially if it is locked in a binary file like an MXD. At least in that case, it isn’t too hard to find someone with a license of ArcMap to help me out. But boy, it would be nice to have a good cartography archival format that isn’t some CSS thing.


It is pretty hard these days not to have a MrSID image behind your vector data. Almost every project I am involved with has a satellite or aerial image behind it. These MrSID images are great because they compress huge raster datasets down to a fraction of their size, but in doing that they cause problems. ArcMap does a great job with MrSID (much better than the old ArcView 3.x ever did) that you almost never notice the difference while panning and zooming, but when you hit that print button the problems begin. The plot file size of these images just balloons to the point of our plotter (HP800ps) just choking on the files. The same plot file using a TIFF is much more manageable. The other big issue with them is you can’t load MrSID into ArcSDE. Well you can, but they don’t work as well as if you had an uncompressed format.

I think the best solution is if you order imagery, always request the “raw” TIFF images as well as MrSID. Down the road you’ll be glad you did.