NASA Ocean Color

ocssw V2022

  
 #include "l12_proto.h"
 #include "vegetation_indices.h"
  
 static int32_t num_bands;  // Number of bands the instrument used has
 static uint idx_modis_band_11 = -1;
 static uint idx_modis_band_1 = -1;
 static int idx_red_min = BAD_INT;  // A band index for red
 static int idx_red_max = BAD_INT;  // A band index for red
 static int idx_grn_min = BAD_INT;  // A band index for green
 static int idx_grn_max = BAD_INT;  // A band index for green
  
 void calculate_cci(l1str *l1rec, float cci[]) {
     double rhos_grn = -0.0;
     double rhos_red = 0.0;
     int32_t num_pixels = l1rec->npix;
  
     for (int32_t idx_pixel = 0; idx_pixel < num_pixels; idx_pixel++) {
         cci[idx_pixel] = UNDEFINED;
         int32_t idx_band = l1rec->l1file->nbands * idx_pixel;
  
         if (instrument_is_hyperspectral(num_bands)) {  // In future, check for hyperspectral ins., not just OCI
             uint grn_width = idx_grn_max - idx_grn_min + 1;  // Difference == width - 1; add 1 back
             uint red_width = idx_red_max - idx_red_min + 1;  // Difference == width - 1; add 1 back
             float *start_of_rhos_grn = &l1rec->rhos[idx_band + idx_grn_min];
             float *start_of_rhos_red = &l1rec->rhos[idx_band + idx_red_min];
  
             rhos_grn = average_rhos_values(start_of_rhos_grn, grn_width);
             rhos_red = average_rhos_values(start_of_rhos_red, red_width);
         } else {  // Multi band instrument
             rhos_grn = l1rec->rhos[idx_band + idx_modis_band_11];
             rhos_red = l1rec->rhos[idx_band + idx_modis_band_1];
         }
  
         double rhos_values[] = {rhos_grn, rhos_red};
         double pixel_elevation = l1rec->dem[idx_pixel];
         double landmask = l1rec->flags[idx_pixel] & LAND_MASK;
         size_t len_rhos_vals = sizeof(rhos_values) / sizeof(rhos_values[0]);
         if (invalid_pixel(pixel_elevation, landmask, rhos_values, len_rhos_vals)) {
             l1rec->flags[idx_pixel] |= PRODFAIL;
             continue;
         }
  
         double cci_value = (rhos_grn - rhos_red) / (rhos_grn + rhos_red);
         cci[idx_pixel] = clamp(cci_value, VI_MINVAL, VI_MAXVAL);
     }
  
     return;
 }
  
 void get_cci(l1str *l1rec, float cci[]) {
     num_bands = l1rec->l1file->nbands;
  
     static bool first_call = true;
     if (first_call) {
         first_call = false;
  
         if (instrument_is_hyperspectral(num_bands)) {
             idx_grn_min = bindex_get(modis_b11_min);
             idx_grn_max = bindex_get(modis_b11_max);
             idx_red_min = bindex_get(red_min);
             idx_red_max = bindex_get(red_max);
  
             if (idx_grn_min == DEFAULT_BAND_INDEX || idx_grn_max == DEFAULT_BAND_INDEX ||
                 idx_red_min == DEFAULT_BAND_INDEX || idx_red_max == DEFAULT_BAND_INDEX) {
                 printf("CCI requires bands near 555 and 645 nm\n");
                 exit(EXIT_FAILURE);
             }
         } else {
             idx_modis_band_11 = bindex_get(555);
             idx_modis_band_1 = bindex_get(645);
  
             if (idx_modis_band_11 < 0 || idx_modis_band_1 < 0) {
                 printf("CCI requires bands near 555 and 645 nm\n");
                 exit(EXIT_FAILURE);
             }
         }
     }
  
     calculate_cci(l1rec, cci);
  
     return;
 }