Fig. 1. Comparison of two schemes. (a) Schematic diagram of SPIF-GSOL; (b) schematic diagram of SPI based on fixed projection pattern sequence; (c) flow chart of SPIF-GSOL algorithm; (d) flow chart of global search

Fig. 2. Template rotation and translation. (a) Original template; (b) right rotation; (c) vertical flip; (d) left rotation; (e) upward translation; (f) downward translation; (g) left translation; (h) right translation; (i) scene for object localization

Fig. 3. Simulated results of template rotation and translation. (a) Original template; (b) right rotation; (c) vertical flip; (d) left rotation; (e) upward translation; (f) downward translation; (g) left translation; (h) right translation

Fig. 4. Template dimensional change. (a) Larger; (b) smaller; (c) thicker; (d) thinner; (e) larger and thicker; (f) larger and thinner; (g) smaller and thicker; (h) smaller and thinner

Fig. 5. Simulated results of template dimensional change. (a) Larger; (b) smaller; (c) thicker; (d) thinner; (e) larger and thicker; (f) larger and thinner; (g) smaller and thicker; (h) smaller and thinner

Fig. 6. Complex scenes and templates. (a) Block the upper part of object; (b) block the lower right part of object; (c) grayscale scene; (d) scene composed of seven different aircrafts; (e) scene composed of the same aircraft in different directions; (f) template corresponding to Fig. 6(a) and (b); (g) template corresponding to Fig. 6(c); (h) template corresponding to Fig. 6(d) and (e)

Fig. 7. Simulated results of complex scene. (a) Block the upper part of object; (b) block the lower right part of object; (c) grayscale scene interference; (d) similar object interference; (e) different attitude interference of the same object

Fig. 8. Optical experiment light path diagram and setup of single-pixel image-free object localization system. (a) Experimental light path diagram; (b) experimental setup

Fig. 9. Experimental results of template rotation and translation. (a) Original template; (b) right rotation; (c) vertical flip; (d) left rotation; (e) upward translation; (f) downward translation; (g) left translation; (h) right translation

Fig. 10. Experiment results of template dimensional change. (a) Larger; (b) smaller; (c) thicker; (d) thinner; (e) larger and thicker; (f) larger and thinner; (g) smaller and thicker; (h) smaller and thinner

Fig. 11. Object localization in complex scenes. (a) Block the upper part of object; (b) block the lower right part of object; (c) similar object interference; (d) different attitude interference of the same object

Fig. 12. Localization results when iterating 100 times of different templates. (a) Template A; (b) template L; (c) localization result of A; (d) localization result of L

Fig. 13. Relative error with iteration times

Fig. 14. Comparison results between proposed method and different “image first, localization later” methods. (a) Variations of localization time with sampling (projection) times; (b) variations of relative error with sampling (projection) times

Fig. 15. DMAE of three methods in different scenes