The as-built survey is a process in the field of geodesy where works carried out during construction are measured and thereby documented. Its main purpose is to ensure that the project has been implemented according to the original plans and drawings, following accuracy and quality standards.

The as-built survey process includes the following steps:

• Baseline data collection: data on existing buildings and the landscape are collected before work starts to establish an accurate baseline.
• Construction monitoring: during the construction process, the progress of works is measured and recorded in stages to ensure that everything follows the design.
• Final survey: a final survey will be carried out after the end of the works to document the final result and to make sure that all elements meet the design requirements.

As a result of the surveying work, as-built drawings and as-built models (land xml, IFC, RVT, etc.) are produced, which reflect the accuracy and quality of the work carried out. All of the as-built measurements will be compiled and archived for future reference. The as-built drawings and as-built models will be of great value decades later when the need arises for design, excavation in the field, or the opening up of the walls of buildings. For example, information gathered in the past about the location of a cable or pipe can help to avoid damaging it during the works.