|
FREC
480 -- ArcMap Quick and Dirty
Getting oriented The easiest way to learn ArcMap is to play with it and experiment with its capabilities. Check out the menu options and tools; see what left and right mouse-clicks bring up. Since ArcMap uses a lot of system resources, do not run more than one ArcMap session at a time. When you launch a new ArcMap session you get a blank window with legend on the left and map frame on the right. When you add a geodatabase or individual data layers to a data frame, they are listed in the Table of Contents and (unless you uncheck them) displayed in the map frame. ![]() As shown here, you will usually see the "standard" and "tools" toolbars below the menu. If you mouse-over the icons you will see their names. You can access many other specialized toolbars via Customize-Toolbars or by right-clicking on any blank area of the project frame. You can drag and drop toolbars wherever you want. ArcCatalog launches as a separate window or as a frame that you can pin in the main window. It lets you manage your geodata files and access the ArcTools menu as well. If you check an individual shapefile or raster with MS-Explorer, you will see that it is actually many files; do not mess with these component files! ArcCatalog lets you copy, move or rename geodata files safely. Multiple geodata layers can be combined and managed in a single Personal Geodatabase file, basically an MS-Access-format database.
![]() ArcTools is a large customizable library of specialized GIS modules. Beyond that, there are additional functions that you can run at the Python window which has replaced the old ArcINFO-style command line. Many commonly-used functions are available in the basic menu: File menu: save the current state of your project; open a saved project; export your map as a graphic file (for inclusion in your project web page). Edit: copy map to clipboard (can paste into Adobe Photoshop or Paint). ArcMap's un-do capability is limited. View: Switch between Data and Layout views (same as little tabs at the bottom left corner of the map frame); create charts or reports; access dataframe Properties (same as right-clicking on the dataframe in the Table of Contents). Bookmarks: create a particular zoom area of your map and re-zoom your map to it. Insert: add cartographic elements (text, legend, scale bar, north arrow, etc.) to your map. You must be in "Layout" view, not "Data" view, to add most of these. Selection menu: select particular features from one or more layers by their attributes and/or by their spatial relationship to other features. Geoprocessing: buffer, clip, intersect, merge, union, dissolve and other feature manipulation tools. Customize: access toolbars; activate extensions such as Spatial Analyst (for raster data) or 3D Analyst (for TIN's and 3D viewing). Windows: activates separate map overview (full extent) and/or magnifier (zoom) windows; restores your Table of Contents frame if you accidentally close it. Help (or use F1 key): Contents tab provides informatoin hierarchically by topic, or use the Index tab to research a specific utility or term. An ArcMap session uses multiple map layers in a single dataframe. The default name of the dataframe is "Layers" (at the top of the Table of Contents). Right-click on "Layers" in the Table of Contents to access the tabbed Data Frame Properties window in which you can set the coordinate system and other properties of the entire dataframe. ![]() Right-click on any individual layer's name in the Table of Contents to access a tabbed Layer Properties window in which you can set the Symbology, layer transparency level, label formats, method of displaying selected features, etc. ![]() GIS data formats The successive projects in this course will introduce various types of map data that ArcMap can handle:
Each shapefile has an associated attribute table that contains one record (row) for each individual geographic feature in the shapefile. The attribute table typically contains multiple attribute data fields (columns) describing the features.
Each raster has an attribute
table that contains one record for each
raster category value. (All
the raster cells in a particular attribute category are treated as a
single feature, even if they are geographically dispersed.)
![]() One of the really useful things about ArcMap is that you can join an external table such as an Excel spreadsheet to a layer's attribute table, based on matching fields in the two tables. This makes it easy to create thematic maps from external data. You will be doing this in the first project. Selecting features You will often want to focus your analysis on specific features in a shapefile, or specific cell categories in a raster. There are multiple ways to select individual features or sets of features from the map or attribute table:
A note on projections and coordinate systems. You will be required specify an appropriate coordinate system (via the data frame Properties tab) for every map image that you include in your submitted projects. Do not submit unprojected maps! Briefly, a projection translates spherical (lat-lon) coordinates to a planar coordinate system such as UTM or State Plane. ArcMap can display unprojected (lat-lon) data in any specified coordinate system, and can even reconcile shapefiles in different specified projections within the same data frame. But be careful about calculating distance or area measures based on unprojected features, even if they are displayed in a projected coordinate system. The actual coordinates of a shapefile are stored in the ".shp" file. There may be a companion ".prj" file specifying what coordinate system that is; otherwise ArcMap may guess. A lot of shapefiles use lat-lon decimal degree coordinates, since that was the default coordinate system for ArcView 3, the popular precursor to ArcMap. To create a new version of a shapefile in the coordinate system of the dataframe, use Data--Export Data to create a copy of the shapefile in the data frame's coordinate system. . (This is often quicker than using Arc's formal reprojection modules.) |