document

The top-down approach to data gathering

SKYDB aims to list every structure in the world in full detail. Stated that way the project sounds impossible. In practice, the goal means there are very few limits on the data contributors can enter. SKYDB has become a valuable resource even while incomplete, largely because of its top-down approach to data gathering. Top-down means starting with the largest, tallest, or most important structures and working downward as coverage expands. For any city or country, it takes relatively little effort to enter the hundred tallest buildings, or the buildings with the most units or floor space. That foundation is already useful and encourages further contributions. Top-down has been SKYDB's traditional model. Editors do use other approaches that have their own advantages:

The canvas approach

Some editors prefer to canvas all structures within an area, regardless of size or importance. The advantage is low maintenance: once an area is complete, missing buildings no longer need to be checked. Canvassing important areas (downtowns, landmark districts) is in effect a variant of top-down and can seed further expansion.

The topic-focused approach

Instead of canvassing a geographic area, some editors index a particular type of structure or the work of a particular company. The result may look scattered on the map, but any complete topical list has clear value.

The random approach

A looser method indexes buildings wherever they happen to be. The pattern is not always meaningful to other users, but the approach is valid and lets contributors collect more data overall. It plants seeds in many areas and inspires others to expand local listings or fill gaps. The top-down approach has shaped SKYDB's coverage for a long time, with a strong emphasis on high-rise buildings and well-known structures. Knowing this helps users understand the database's coverage profile. Other approaches are equally welcome.