Fig. 1. Transmission spectrum acquisition platform of sugarcanes
1: Probe; 2: Black sponge pad; 3: Halogen lamp;4: Sample fixing cylinder; 5: Sugarcane sample;6: Optical fiber; 7: Spectrometer; 8: Cable; 9. Laptop

Fig. 2. The sugarcane samples before and after wax removal and the sketch of transmittance measurement positions

Fig. 3. Spectral difference of sugarcane before and after wax removal
CWR: Cane wax removed; OS: Original sample
(a): Transmission spectra at different sampling positions of a sugarcane sample; (b): Correlation between transmittance spectra and sucrose

Fig. 4. Average spectral transmittance of samples at different angles
(a): Original sample; (b): Cane wax removed

Fig. 5. Frequency of each wavelength selected by VCR-ACO algorithm

Fig. 6. Scatter plot of the model established by the wavelength selected by VRC-ACO algorithm
(a): Calibration set; (b): Prediction set