Informal urban settlements are critical for sustainable development but challenging for computational analytics due to a lack of data, raising issues on data representativeness and the digital divide. This study explores a hybrid approach integrating conventional urban design theory and digitizing methods to compute places and associated human activities in a data-absent environment. Using an informal settlement area in Beijing as a testing site, this study demonstrates a digitizing pipeline that could be applied to other data-poor sites. Research findings reveal spatial characteristics of observed human activity and associated factors relevant to the informal use of space. Such investigation in computing informal places and human activity brings vital value to address the current digital divide and spatial justice in urban development.