You must first decide which thematic layers your unique application and information needs will require. What data themes comprise your main landscapes? Then, you go into greater detail about each topic layer.
Each thematic layer will be characterized, leading to the defining of common geodatabase data items as feature classes, tables, relationship classes, raster datasets, subtypes, topologies, domains, and so forth.
Try to describe each subject in terms of its visual representations, anticipated uses in the GIS, potential data sources, and levels of resolution when identifying thematic layers in your design. How will this information’s components be displayed at each scale, for instance, and at what scales and extents would you need to use it? These qualities aid in defining the high-level contents anticipated for each theme.
An illustration of a data theme description for ownership parcels in a cadastral application is shown here.
Geo-database steps
Eleven steps to geodatabase design
Step 1. Identify the information products that your GIS will help you produce and manage.
Your organization’s work should be reflected in your GIS database design. Consider creating and keeping a list of your organization’s essential roles, 3D views, analytic models, Web mapping apps, data flows, database reports, and other mission-based requirements. List the data sources that you are currently using for this project. Use them to inform your demands for data design. Decide which 2D and 3D digital basemaps are necessary for your applications. As you pan, zoom, and investigate each basemap’s contents, note the set of map scales that will be displayed.
Step 2. Based on the information you need, identify the main data topics.
Give a more thorough definition of a few of the main features of each data theme. Choose the intended application for each dataset: editing, GIS modeling and analysis, displaying your company’s workflows, mapping, or 3D presentation. In addition, describe how the subject is presented, including its symbology, text labels, and commentary. You should also specify the map’s use, data sources, and spatial representations for each given map scale. Think on how each map layer will be displayed in conjunction with other important layers. Think about how information will be used with other datasets when modeling and analyzing (for example, how they are combined and integrated). You can then recognize some important spatial linkages and data integrity principles. Make sure to incorporate these display and analysis properties for 2D and 3D maps into your database design.
Step 3. The scale ranges and spatial representations of each data theme at each scale should be specified.
Data is gathered for use at a range of different map scales. For each map scale, assign your geographic representation. Variations in geographic representation between map scales are common (for example, from polygon to line or point). For use at lesser sizes, you may frequently need to generalize the feature representations. Image pyramids can be used to resample rasters. You might need to gather more representations for various map scales in other circumstances.
Step 4. Each representation should be broken down into one or more geographic datasets.
Point, line, and polygon feature classes are used to model discrete features. Advanced data types like topologies, networks, and terrains can be used to model the connections between the components of a layer as well as between different datasets. Mosaics and catalog collections are methods for managing very large collections for raster datasets. Rasters, terrains, and characteristics like contours can all be used to model surfaces.
Step 5. Define the behavior and structure of a tabular database for descriptive attributes.
Determine the types of attribute fields and columns. Tables may also incorporate relationships, sub-types, and attribute domains. Define any legal parameters, attribute ranges, and categories (for use as domains). Utilize sub-types to regulate behavior. Determine linkages and relationships in tabular form for relationship classes.
part 2 will cover the rest……
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