civil documents? photographs?

老师们， 刚刚网上递交了给在中国的妈妈的Immigrant Visa and Alien Registration Application. 然后 confirmation page 要求1. Obtain and submit required supporting civil documents.
2. Obtain and submit photographs that meet the department of state's visa requirements. 3. review the information specific to U.S. Embassy general where your visa interview will occur.
有点吃惊， 材料和照片不是应该面试时带到广州领馆的吗？难道该寄到NVC？ 我先前已选过所有材料用电子文档发送，那么是否该扫描并email 到NVC?
拜谢！！