As SIFT features are invariant to rotation and scaling, we employ SIFT to extract feature points.

由于SIFT特征对旋转和缩放具有不变性，该算法利用SIFT提取图像的特征点。

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How to extract the rotation invariant feature and improve the stability of the noise is still an unsolved problem of the area of content-based 3d models retrieval.

提取关于坐标旋转不变的特征描述符以及提高特征描述符对噪声的鲁棒性是基于内容三维模型检索技术中有待进一步研究解决的问题之一。

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