In the marriage supplements, the documents that a bride and groom had to submit when they got married, you will usually encounter a certificate stating that the groom had fulfilled his military duties. About half the time, this form will include a physical description. See elsewhere on this site for a list of terms with their translations.
The example below is the certificate for Arend Kastein, showing that he was 1.74 m (5’9″) tall, an oval face, ordinary stern, blue eyes, an ordinary nose and mouth, round child and black hair and eyebrows. That seems to match his photo (see to the right).