Would someone please explain why it's considered a best practice to NOT use shapefiles for vectors involved in spatial operations? I've been using stream shapefiles (derived from geomorphon analysis) for Arc Hydro DEM Reconditioning. Thank you!
Shape files have different precision when storing coordinates then feature classes. It is also the question of projection/spatial reference that should be consistent across all layers used in Arc Hydro analyses (raster and vector). Use of feature classes (from the same feature dataset as recommended by Arc Hydro) ensures that. So the “best practice” is to import your shape file(s) into the Arc Hydro project geodatabase/feature dataset and then use those imported features and its derivatives as input into Arc Hydro and other geoprocessing tools. If the layer is used for visualization purposes only, then this is not necessary.
There are a number of other reasons why you should in general prefer use of geodatabases (and thus feature classes) over shape files. It is a much richer data modeling environment than what shape files provide.
This is probably a dumb question, but what if I save a vector as a shapefile to a geodatabase? Like, when I save my lines I use Raster To Polyline, which saves the lines to the geodatabase. But the saved lines have a .shp extension? If this is wrong, how would I save them as something other than a shapefile?
You cannot use the "." in the name of the feature class you are saving into a gdb. So you cannot use something like "aaa.shp" as a name of an output that goes into a gdb (you can if the target is a folder but NOT if it is a gdb). So what you do is just call your output "aaa" and save it in the gdb and you will create a feature class. For feature classes that are used in the analyses, you should have them within a feature dataset - that will allow you to use them in geometric networks, topology, etc. and will enforce application of consistent spatial reference across all the layers in that feature dataset.
(Sorry to drag this out! You are being very helpful, I just want to make sure I understand.)
Let's say I select a county from a counties feature class and use Export Data to create a new layer that shows only that one county (we'll call the county "aaa"). I have the option of saving it to my .gdb as "aaa.shp." Does that mean I'm not truly saving it to the file geodatabase? Or am I not truly saving it as a shapefile? ArcMap automatically inserts the ".shp" ending, but I don't think I need it to save the aaa county as a new layer.
The only time ArcMap should put .shp at the end of a layer name you provide is if you are storing the output into a FOLDER (e.g. "C:\mylocation"). Then the output will be stored as a shape file and the name you provided will get the .shp name extension. If the target for the output is a geodatabase (e.g. "C:\mylocation.gdb") then the output will be stored within that gdb as a feature class and will not get an extension .shp. Make sure that you create the .gdb using ArcMap/Catalog. Give it a try. If this is not working for you (or working differently), i suggest we set up a webcast and go over it together.
I actually think I've got it worked out! I really appreciate you taking the time to explain this to me. I started working on a new hu12 with Arc Hydro, and I see what you're saying. Thanks again!
