Estimation of Leaf Area Index and Plant Area Index of a Submerged Macrophyte Canopy Using Digital Photography
Figure 1
The influence of photograph orientation on digital number (DN) differences between vegetation and background pixels in vertical photographs of aquatic vegetation.
A and B show vertical upward- and downward-oriented photographs, respectively. Histograms of DNs for red, blue and green bands are also shown for upward-oriented (A-Red, A-Blue and A-Green) and downward-oriented (B-Red, B-Blue and B-Green) photographs.