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Spatial Analysis Lab (SAL) |
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How to make a portable map... Steps for distributing ArcGIS maps and data Back to the
6. Data Dictionaries (optional)
In order for you to be able to share your ArcMap map (.mxd) with other GIS users (and/or your instructor) you will need to provide them with not only the .mxd but also the data used in the map. Not only that, but the .mxd must be able to locate the data in order for everything to display properly. To insure that the .mxd still works once it is moved you will need to set up a PORTABLE .MXD. This requires two things: proper data management and the use of Relative Paths for the .mxd itself.
For sharing of data and maps, you will want everything stored in a single folder (with optional sub-folders inside). In this folder you should have all of your GIS data as well as your .mxd file(s). As always with GIS related matters, creating file and folder names without spaces or non-alphanumeric characters is advised. So for example, you might create a GIS_proj folder in C:\temp (strongly recommended, as opposed to building your project on the U:\ drive or other locations). Within this main GIS_proj folder you might have a series of sub-folders (e.g., data, maps, exports, documents, etc.) sorting your various files into logical categories. Be sure that your GIS data files are complete (i.e., a shapefile requires at least 3 separate files to properly display). The recommended tool for copying and moving GIS data is ArcCatalog (not Windows Explorer), especially for Coverages and Grids. Thus, you might have a data folder something like this:
In the example above exported maps (saved as jpeg files) have been stored in the exports folder. The misc_documents folder might contain things like a data dictionary, map abstracts, final reports, supplemental data (word documents or spreadsheets), etc. Note that all of your data could be in a single data folder, or you may have multiple data folders (data_archives, data_city, data_current, etc). In the example above, old data layers have been moved to the data_archive folder and the grids have been stored in the data_raster folder. The data folder thus contains only vector data layers that are used in the current .mxd file(s). On the other hand, you could have all of your files (data, .mxd, etc.) in one single folder like this:
Which is better? Depends on your preferences, the complexity of your project and who you plan to share your data with.
2 Create Your Map(s) using RELATIVE PATHS Having logically organized your data, you can build your .mxd(s), which will be saved to the GIS_proj folder (optionally to your GIS_proj\mxds or GIS_proj\maps sub-folder). Once you have a working .mxd (using data from your project folder) you will need to set it's properties to use Relative Paths.
If you have a pre-existing map project you can copy it to your GIS_proj folder. In this case you will need to manually re-path each data layer to make sure it is using the data in your GIS_proj folder (and not another copy of the same data on your U:\ drive or the J:\ drive or the C:\temp folder...). To check (and if need be re-path) a data layer in ArcMap: · In ArcMap, right-click on a data layer in the Table of Contents and choose Properties... · Click on the Source tab to view the current data source path · If your data path is not C:\temp\GIS_proj\data (or whatever your project folder name is) you need to change the path: o Click on the Set Data Source... tab o In the Data Source dialog box. If you need to reset the source data location browse to your project folder (i.e., C:\temp\GIS_proj\data) and select the appropriate data layer o Click on the Set Data Source... button · Click OK to close the layer Properties box · · To see the sources of all of the data in an .mxd you can also select the List by Source tab at the top of the Table of Contents
Once you have your .mxd (using data that is stored in the same project folder as the .mxd itself), you need to insure that your .mxd is using Relative Paths (this is critical – otherwise your .mxd will only work when your folder is stored in the C:\temp folder of a computer and will not be truly portable): · In ArcMap, choose Map Document Properties... from the File menu · Check the check box beside Store relative path names to data sources · Click OK · Save your .mxd
To test your map projects, copy your entire GIS_proj folder (including both the data and the .mxd(s) using relative paths) to your U:\ drive or a external / thumb drive. You should be able to move to a new computer and open the .mxd file(s) from the U:\ drive or from the external drive (as well as from the C:\temp folder), in short, from wherever your GIS_proj folder is. Once you have moved your folder to a new location open the .mxd and check the sources. All of the data should be coming from the new location (i.e., from your U:/ drive or external drive). And of course, there should be no red !'s. An even better test is to have someone else try your .mxd from their computer using their login. The goal of these tests is to make sure that your .mxd really is using relative paths and that all the data was properly copied with the .mxd. You can also use the Source tab below the ArcMap Table of Contents to display where the data being used in a .mxd is stored. For a portable map project, all of the data should be inside the GIS_proj folder, ideally in the data folder(s).
Having verified that all of your data is where it should be (in the GIS_proj folder) and that all of your .mxd files are using relative paths and are using the data in the GIS_proj folder, you can share you map project with others by giving them the entire GIS_proj folder (on a CD, etc.).
As you build your .mxd (having first set the Map Properties to store relative path names) you may also want to create some Layer files. These layer files (which may be stored to their own layers sub-folder) allow the recipient of your map project to add additional data to your project or create their own maps while benefiting from your symbology (and/or labeling of data and/or selections of data). They also allow you to create additional maps using the same symbology. Layer files can be created for any data layer in your map: · In ArcMap, right-click on a data layer in the Table of Contents and choose Save As Layer File... · Browse to the folder you wish to save your layer files in · Rename the layer file if you wish · Click Save
NOTE: Layer Files will inherit the same properties as the .mxd - in other words, if your .mxd is using Relative Paths, so will your Layer Files. But if you have not set your .mxd to Relative Paths (and it is still using the default Absolute Paths setting) than any Layer Files you create will not have Relative Paths. The .mxd needs to be set First (before you create your Layer Files). Changing the .mxd once the Layer Files have been created does not change the Layer Files...
A Data Dictionary is a document outlining (in brief) the various data sets used in a given map or project. This is, in effect, a very limited form of metadata, with the information about a set of layers being compiled into a single document. Typically a data dictionary might include: · Name of the Layer · Data format (coverage, shapefile, grid, etc.) · Source · Location (where stored in your project folder data structure · Projection & Coordinate System information · Brief abstract of how the data is used in the project · Brief detail of key attributes (and attribute values) · Other information relevant to the project (processing steps, how the data relates Data dictionaries can be developed in MS Word or Excel, a text editor or an Access database. A data dictionary should be seen as a summary supplement to (as opposed to a replacement for) the full metadata available for each layer. Data layers can be listed alphabetically, grouped by source or type, or otherwise logically organized as appropriate for your project. Layer files can also be included in the Data Dictionary. Map Abstracts for your .mxd files or for exported would more logically be listed separately (typically as text). Below is Data Dictionary example for some of the data layers (shown in the examples above):
* All data layers are in Lat-Long, decimal degrees, WGS84 datum
A Map Abstract gives a brief summary of a map, typically including the main intent or objective as well as key data layers and/or symbology. Parameters used for symbology (classifications, etc.) may also be included, as may coordinate system and/or data accuracy comments. Below is an example of a hypothetical pair of map abstracts from the project folder above:
Elevation & Topography (elev.mxd) Map of southwestern USA depicting elevation and topography. Elevation is shown using a DEM with a color ramp. Topography is shown via a BW hillshade (used in combination with the DEM elevation color ramp). In addition, large cities of the area are shown and labeled.
Population Density (pop_dens.mxd) Map of southwestern USA depicting population density by county. Population figures are from 1999 and are categorized as high-medium-low (0-100, 100-1000, 1000 + population/square mile). In addition, large cities of the area are shown and labeled.
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