This paper - Quality Control in Visualization Processes - was submitted and accepted at the ecaade 2004 in Copenhagen. The paper discusses reasons for and ways of introducing a quality control in visualization processes. It is written by Uffe Lentz (main author) and Andreas Lykke-Olesen (co-author) and draws conclusions from the consultancy report Evaluation of Visualization Methods made for ncc in 2003. Abstract Computer visualizations of planned built environment and infrastructures are increasingly used as a basis for democratic decisions when the impact of the projects is of wide-ranging interests and influence. It is of great importance for the democratic process that all aspects of the material in a project can be trusted as a basis for discussion and decisions among politicians and citizens. This paper describes the objective aspects of the quality of data in the information basis for 3D visualizations and it calculates the precision that can be achieved by the known methods of 3D-CAD visualization. Furthermore, the paper suggests a model that can secure sufficient quality in future visualization work processes by accumulating documentation for both the factual basic data and information that carry the aim and meaning of the message and make this information accessible through the visualization. read the entire paper in pdf here