ArcMap Etiquette

Whenever you start an ArcMap project you should always ensure that you have established a proper working environment. Some of the parameters you should pay attention to:

Absolute and relative paths in ArcMap

When you create an ArcMap document, you should specify that paths be stored as relative paths. To set this option, look under the File menu and click Map Document Properties. Here, you can specify whether to store absolute or relative paths.

When you save the document with relative paths, the application converts paths into paths relative to the location where you stored the document (e.g., the current directory [C:\data\]).

Setting the location for the default geodatabase

ArcMap, by default, will store any newly created files in a default geodatabase (C:\Documents and Settings\...\My Documents\ ArcGIS\Default.gdb). Since storing data in the default geodatabase location is problematic (e.g., doing so will increase the length of time it takes you to log onto the system), you should always identify an appropriate location for the geodatabase. Given the practice in most geoscience labs in the Department of Geography, the appropriate location for storing your data / creating a geodatabase is C:\data\. Thus, your first step whenever starting a project / lab is to set the default database to reside in C:\data\Labx (where x would be the lab #). So, if you will be working with a geodatabase, follow the instructions listed below:

Ensure the default geodatabase is explicitly set:

1. Click on Catalog
2. Select Folder Connections
3. Confirm that C:\data\Labx is listed as a Folder Connection
4. Right-mouse click on the appropriate .gdb
5. Click on the entry ‘Make Default Geodatabase’

Establishing meaningful geoprocessing parameters

In order to ensure that subsequent steps produce the correct output, and to ensure that various outputs get placed in the correct location, we should explicitly set some of the geoprocessing environment options.  To do this, click on Geoprocessing / Environments…  

• Select Workspace and ensure that the Current and Scratch Workspaces are set to the appropriate geodatabase. 
• Select Processing Extent and set the Extent to an existing layer, or explicitly set the extent to something appropriate.
• Under Raster Analysis set the Cell Size and Mask to an existing raster layer.  Click on OK.  Now, whenever a feature is converted to a raster, or a raster layer is created, its resolution (and extent) will match the existing raster file.

By default ArcMap does NOT allow you to overwrite the previous outputs of a geoprocessing operation (that is, if you have to redo a geoprocessing operation you must give the output a different name).  You can, however, override that default by clicking on Geoprocessing Options (under Geoprocessing) and then selecting ◙ Overwrite the outputs of geoprocessing operations.

You should confirm the environmental settings / geoprocessing parameters every time you start your work.

It is also a highly recommended practice to not store / create ArcMap data or documents in a directory name that contains spaces (that is, it is recommended that you do not store any files in, for example, C:\Documents and Settings\...\My Documents\ even though that is where ArcMap indicates that that is where it wants to store the default geodatabase!). You should also not create files with names that begin with numbers (e.g., 123layer.shp). While it is possible to do so, and in most cases it will not create a problem, there are some known issues that arise with some components of ArcMap (and with add-on programs such as FragStats) if the directory name contains spaces / the filename begins with a number.

It is a good idea to keep the number of connections in ArcCatalog to a minimum--every time you start ArcMap it checks the connections, and if some of them don't exist (e.g., files on a network drive that isn't currently connected) it can take some time for ArcMap to 'drop' the connection.

It is a good practice to modify Windows Explorer so that, by default, it shows all known file extensions. To do this, click on Organize, then on Folder and search options. Then, in the View tab, uncheck Hide extensions for known file types. Doing this will make it much easier to find files.