Table 6.

Studies analyzing the shape of organs solely or in combination with other features

Organ	Features	Shape descriptor	Studies
Leaf	Shape	SMSD	[24, 58, 82, 89, 141]
		SMSD, FD	[1]
		SMSD, moments (Hu)	[40, 110, 137]
		SMSD, moments (TMI), FD	[106]
		SMSD, moments (Hu, ZMI), FD	[72]
		SMSD, DFH	[146]
		Moments (Hu)	[102]
		Moments (Hu, ZMI)	[138]
		Moments (ZMI, LMI, TMI)	[159]
		FD	[147]
		CCD	[130]
		CCD, AC	[46]
		AT	[6]
		TAR, TSL, TOA, TSLA	[94]
		TAR, TSL, SC, salient points description	[92]
		CSS	[45]
		SMSD, CSS	[15]
		CSS, velocity representation	[28]
		HoCS	[76]
		SRVF	[77]
		IDSC	[11]
		I-IDSC, Gaussian shape pyramid	[158]
		MDM	[62]
		SIFT	[26, 59, 81]
		HOG	[41, 111, 145]
		HOG, central moments of order	[155]
		SURF	[103]
		Multi-scale overlapped block LBP	[121]
		MARCH	[134, 135]
		Describe leaf edge variation	[54]
		FD, procrustes analysis	[56]
		Polygonal approximation, invariant attributes sequence representation	[38, 39]
		Minimum perimeter polygons	[100]
		HOUGH, Fourier, EOH, LEOH, DFH	[99]
		Moments (Hu), centroid-Radii model, binary-Superposition	[22]
		Isomap, supervised isomap	[42]
		MLLDE algorithm	[156]
		MICA	[157]
		Parameters of the compound leaf model, parameters of the polygonal leaflet model, averaged parameters of base and apex models, averaged CSS-based contour parameters	[19]
		Leaf landmarks (leaf apex, the leaf base, centroid)	[119, 120]
		Detecting different leaf parts (local translational symmetry of small regions, local symmetry of depth indention)	[97]
		Detecting petitole shape (local translational symmetry of width)	[96]
		Geometric properties of local maxima and inflexion points	[98]
	Shape, color	SMSD	[16]
		SMSD, FD	[116]
		PHOG, Wavelet features	[87]
		SIFT	[27]
	Shape, margin	CSS, detecting teeth and pits	[18, 20, 21]
		SMSD, moments (Hu), MDM, AMD	[73]
		Advanced SC	[93]
	Shape, texture	SMSD, moments (Hu)	[154]
		CCD, AC	[10]
		CT, moments (Hu)	[23]
		Multi-resolution and multi-directional CT	[115]
		RSC	[114]
		CDS	[140]
		SC	[143]
		Advanced SC	[91]
		DS-LBP	[136]
		SURF, EOH, HOUGH	[68]
	Shape, vein	SMSD	[5, 144]
		RPWFF, FracDim, moments (Hu)	[65]
		FracDim	[14, 67]
		SC, SIFT	[139]
		Minimum perimeter polygons	[101, 107, 108]
		Contour covariance	[4]
	Shape, color, texture	SIFT, high curvature points on the contour	[74]
		SMSD, BSS, RMI, ACH, CPDH, FD	[148]
	Shape, color, texture, vein	SMSD	[43, 48]
Flower	Shape	SMSD	[129]
		Mathematical descriptor for petal shape	[128]
		Zero-crossing rate, the minimum distance, contour line’s length from the contour image	[64]
	Shape, color	Shape density distribution, edge density distribution	[30]
		SMSD, moments (Hu), FracDim, CCD	[3]
		SIFT, Dense SIFT, feature context	[117]
		CDD	[57]
		CDS, SMSD	[60]
	Shape, texture	SIFT	[149]
	Shape, color, texture	Edge densities, edge directions, moments (Hu)	[29]
		CSS	[112]
		SIFT	[104]
		SIFT, HOG	[105]
		SURF, EOH, HOUGH	[68]
Fruit, bark, full plant	Shape, texture	SURF, EOH, HOUGH	[68]

Abbreviations not explained in the text–BSS basic shape statistics, CPDH contour point distribution histogram, CT curvelet transform, EOH edge orientation histogram, DFH directional fragment histogram, DS-LBP dual-scale decomposition and local binary descriptors, Fourier Fourier histogram, HOUGH histogram of lines orientation and position, LEOH local edge orientation histogram, MICA multilinear independent component analysis, MLLDE modified locally linear discriminant embedding, PHOG pyramid histograms of oriented gradients, RMI regional moments of inertia, RPWFF ring projection wavelet fractal feature, RSC relative sub-image coefficients