Jump to content

 
Photo

shapefiles or GDB?

- - - - -

  • Please log in to reply
7 replies to this topic

#1
Dennis McClendon

Dennis McClendon

    Hall of Fame

  • Validated Member
  • PipPipPipPipPipPipPip
  • 1,084 posts
  • Gender:Male
  • Location:Chicago
  • Interests:map design, large-scale maps of cities
  • United States

I'm trying to understand the reasons one might use a geodatabase rather than a hard drive full of shapefile folders.  I'm sure most ESRI users work with the same small part of the world day in and day out, so a default dataset makes a lot of sense for them.  But one day I'm mapping building footprints in downtown Las Cruces at 1:5000 and the next day Alaskan airports at 1:2 million.  Under what situations would I want to have a geodatabase rather than various folders?


Dennis McClendon, Chicago CartoGraphics
chicagocarto.com

#2
katzmoye

katzmoye

    Contributor

  • Validated Member
  • PipPip
  • 14 posts
  • Gender:Female
  • Location:Portland, OR
  • United States

I find GDBs offer a lot more functionality (and organization) than shapefiles - topology being a big plus, plus annotation. There are also some new distribution tools, the ability to compact/compress, make layer packages, etc. I also like using feature datasets to set a common projection, so that any data I create or want to store has to have the same (forcing me to pay attention!). You can also store rasters in a geodatabse. If you do a lot of sharing of data with others it is convenient to share a single gdb (or replica, or schema). I also enjoy using subtypes and domains, especially for fieldwork and using ArcPad. With ArcPad Developer it is quick and easy to turn a subtype/domain situation into dropdowns and pick lists for field forms, etc.



#3
razornole

razornole

    Legendary Contributor

  • Validated Member
  • PipPipPipPipPip
  • 452 posts
  • Gender:Male
  • Location:Ozark Plateau, Arkansas
  • Interests:Photography, Cartography, Down-river canoeing, Backpacking, Cross country biking, Geomorphology, Ornithology, Ecology, Quaternary, and last but first; drinking beer on the beach.
  • United States

I, much like yourself, am mapping all over the world.  I have always taken data from geodatabases and converted them to shapefiles.  However once I began to collect my own data with ArcPad, I stated making geodatabases.  Now I am back to the process of creating databases out of my shapefiles, a complete 180 degree turn.  The selling point for me was when I had to work with four different State road layers and bring them together in one map. Every DOT had a different method of doing their attribute tables, and I couldn't select by attribute.  I find that they are much easier to edit and more importantly customize.  I get ride of a lot of the crap that the feds and state agencies use.  I primarily do outdoor recreation maps so I have databases for streams, one for roads, one for points of interests, etc.  If I get another project in a different/new area, I just add those data to my current database.

 

I'm self taught in GIS, so I don't know all fancy terminology.

 

kru


"Ah, to see the world with the eyes of the gods is geography--to know cities and tribes, mountains and rivers, earth and sea, this is our gift."
Strabo 22AD

#4
David Medeiros

David Medeiros

    Hall of Fame

  • Validated Member
  • PipPipPipPipPipPipPip
  • 1,089 posts
  • Gender:Male
  • Location:Redwood City CA
  • Interests:Cartography, wood working, wooden boats, fishing, camping, overland travel, exploring.
  • United States


As mentioned GDBs allow for more functionality than a .shp file, in particular

topology. GDBs also force recalculations for area and length if a feature is
edited. A .shp file on the other hand will continue to show the original area
or length in the attributes even after editing. GDBs allow for longer field
names, unlimited number of attribute fields, and unlimited file sizes or
feature counts. Shapefile have a limit to the number of features and attributes
they can include and in many cases converting a large table to a .shp file
instead of a feature class cuts out the extra data.


 

GDBs also support feature datasets which further help organize data - so
instead of one  GDB for roads, one for rivers etc you can have a GDB for a
particular topic, extent or scale and have feature datasets inside the GDB that
organize the features by theme (rivers, roads...). Feature datasets also allow
you to set a coordinate system up front so anything you add to the feature
dataset is projected to match.


That said, if you're not really calling data from the GDB as part of any
analysis or dynamic mapping but as base layers for cartographic use it may only
be a slightly fancier folder to you. Shapefiles are of course more portable
than a GDB. If I want to share a particular feature class with someone I can't
give them just that feature class, I have to give them the whole GDB unless I
export it to .shp first.



 



 



 


GIS Reference and Instruction Specialist, Stanford Geospatial Center.

 

www.mapbliss.com

 


#5
katzmoye

katzmoye

    Contributor

  • Validated Member
  • PipPip
  • 14 posts
  • Gender:Female
  • Location:Portland, OR
  • United States

Please note that personal GDBs do limit file size, etc. while file GDBs do not. 

 

I've been working in GIS for a long time and I still receive shapefiles where someone sends only the .shp file and not all the other pieces. I find GDBs much easier to zip and ship. Typically I just copy the entire gdb into a folder, strip out what I don't need, zip the folder and send.



#6
frax

frax

    Hall of Fame

  • Associate Admin
  • PipPipPipPipPipPipPip
  • 2,320 posts
  • Gender:Male
  • Location:Stockholm, Sweden
  • Interests:music, hiking, friends, nature, photography, traveling. and maps!
  • Sweden

The only reason for using personal gdb nowadays is possible for portability or if one does any manipulation using Microsoft Access, otherwise avoid!

 

File geodatabases also support cartographic representations.

 

I try to use file geodatabases when I create something new, but I don't bother with converting old stuff, stuff that I need to use with other software (like Global Mapper) or things that I have downloaded and don't need to manipulate further.


Hugo Ahlenius
Nordpil - custom maps and GIS
http://nordpil.com/
Twitter

#7
David Medeiros

David Medeiros

    Hall of Fame

  • Validated Member
  • PipPipPipPipPipPipPip
  • 1,089 posts
  • Gender:Male
  • Location:Redwood City CA
  • Interests:Cartography, wood working, wooden boats, fishing, camping, overland travel, exploring.
  • United States

The only reason for using personal gdb nowadays is possible for portability or if one does any manipulation using Microsoft Access, otherwise avoid!

 

File geodatabases also support cartographic representations.

 

I try to use file geodatabases when I create something new, but I don't bother with converting old stuff, stuff that I need to use with other software (like Global Mapper) or things that I have downloaded and don't need to manipulate further.

 

Agreed, and this is probably why I assumed he was referring to file GDBs.

 

As for sending files, I find it easier to send the .shp files than clean out a GDB for zipping. But I know enough to send all of the files. One way to avoid any issues in moving GIS files around is to use ArcCatalog which sees the files as whole and moves all of the related files in the background for you.

 

On a related note, if you have an active connection in ArcGIS to a GDB and you move or copy the GDB in Win Explorer some locked files may not be copied over and the whole copied GDB becomes useless. So there are traps every where really.


GIS Reference and Instruction Specialist, Stanford Geospatial Center.

 

www.mapbliss.com

 


#8
AndyM

AndyM

    Key Contributor

  • Validated Member
  • PipPipPip
  • 57 posts
  • Location:Ottawa
  • Canada

Also, when dealing with large datasets, ArcMap can deal with drawing, querying, etc much faster in a file gdb or SDE fgdb than in shapefile format.  I haven't used personal geodatabases, but apparently they become inefficient as they get larger.

 

http://help.arcgis.c...000000pt000000/






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

-->