Ensuring the Integrity of the GIS Data
Since the PhillyTreeMap user community consists of individuals with varying levels of horticultural experience, Azavea created several important features to make the inventory process easier to understand and keep the inventory data as accurate as possible. First, an integrated, region-specific Tree Key on the site guides users through the process of identifying a tree species, ensuring accurate information is entered into the database. The Tree Key provides images of leaves, flowers and other distinctive features that users can compare to an existing tree to help determine its species. An FAQ page provides important how-to information about the inventory process, including a helpful video tutorial on measuring tree trunk diameters.
Azavea also implemented a prototype “reputation” system and series of user levels. General users can add new trees and edit the majority of tree detail fields. Advanced users (often members of a horticultural group or trained arborists) can edit additional fields such as condition and height which require more experience to accurately assess. The reputation system enables users to accumulate points by adding trees and editing tree information. Advanced users can also express their opinion regarding the quality of an edit, which grants additional reputation points to the user who made the edit. General users who demonstrate a consistent pattern of accurate edits will accumulate “reputation points” that provide them with additional editing options on the site.
Other features provide additional data quality checks that reduce erroneous information. Those checks include flagging discrepancies in the height and diameter of a tree based on its species or the ratio between the diameter at breast height and the total height of a tree. Drop-down lists and autocomplete features require users to make selections based on selected lists. For example, PhillyTreeMap provides species restrictions that prohibit users from entering tree species that are not normally found in the area covered by the inventory.