Fig. 1. Basic framework of SDR-CycleGAN

Fig. 2. Network structure of style encoder

Fig. 3. Network structure of content encoder

Fig. 4. Network structure of content domain translation module

Fig. 5. Network structure of decoder

Fig. 6. Network structure of discriminator

Fig. 7. Working process diagram of discriminator

Fig. 8. Samples of SEN1-2 dataset

Fig. 9. Samples of SARptical dataset

Fig. 10. Samples of WHU-SEN-City dataset. (a) SAR image; (b) ORS image

Fig. 11. Image blocks of WHU-SEN-City dataset

Fig. 12. Schematic diagram of image cutting. (a) Example of scene image; (b) image blocks

Fig. 13. Examples of SAR image to ORS image translation on SEN1-2 dataset

Fig. 14. Examples of ORS image to SAR image translation on SEN1-2 dataset

Fig. 15. Examples of SAR image to ORS image translation on SARptical dataset

Fig. 16. Examples of ORS image to SAR image translation on SARptical dataset

Fig. 17. Examples of SAR image to ORS image translation on WHU-SEN-City dataset. (a) SAR images; (b) ORS images; (c) BRIT translation results; (d) CR-CycleGAN translation results; (e) MUNIT translation results; (f) S-CycleGAN translation results; (g) DSMAP translation results; (h) SDR-CycleGAN translation results

Fig. 18. Examples of ORS image to SAR image translation on WHU-SEN-City dataset. (a) SAR images; (b) ORS images; (c) BRIT translation results; (d) CR-CycleGAN translation results; (e) S-CycleGAN translation results; (f) MUNIT translation results; (g) DSMAP translation results; (h) SDR-CycleGAN translation results

Table 1. Quality assessments of SAR image to ORS image translation on SEN1-2 dataset

Table 2. Quality assessments of ORS image to SAR image translation on SEN1-2 dataset

Table 3. Quality assessments of SAR image to ORS image translation on SARptical dataset

Table 4. Quality assessments of ORS image to SAR image translation on SARptical dataset

Table 5. Quality assessment of SAR image to ORS image translation on WHU-SEN-City dataset

Table 6. Quality assessment of ORS image to SAR image translation on WHU-SEN-City dataset