In this work, we present a blind watermark method for protecting the copyright of CityGML model. The method applies the octree-based segmentation method and embeds the watermark by using quantization index modulation (QIM) to alter the DCT coefficient of sphere radii in each partition of each selected segment. The experimental results show that the proposed method has certain robustness to the cropping attack and noise addition.

CityGML, watermarking, octree, segmentation, QIM.