Correction: Tilly, N. et al. Fusion of Plant Height and Vegetation Indices for the Estimation of Barley Biomass. Remote Sens. 2015, 7, 11449–11480

After publication of the research paper [1] an error during the data analysis process was recognized. In Table 4 [1] the units for fresh and dry biomass are stated as being g/m². However, the values actually refer to the sampling area (0.2 m by 0.2 m), hence each value should have been multiplied by 25 to extrapolate it to g/m². Unfortunately, this step was missed out.

All analyses were re-executed based on the correct values, and the corresponding tables and figures are presented in the same order as in the paper in the following Table 1, Table 2 and Table 3, Figure 1, Figure 2 and Figure 3. Thus, the stated sensitivity thresholds for the saturation of the NDVI and RGBVI must also be corrected to be about 185 g/m² and 1375 g/m² for dry and fresh biomass, respectively. In comparison to the originally stated values the R² and d values for all models did not change and hence, the overall statements of the study are correct. For the linear BRMs, the value ranges were extended through the multiplication by 25 and thus, the SE_E and RMSE differ. In contrast, the log-transformation for the exponential BRMs converted the factor to a constant summand, which is added to each value (ln(25) ≅ 3.22). Consequently, the absolute difference between the biomass values and hence, the SE_E and RMSE, do not differ. We apologize for any inconvenience this has caused.

Table 1. Correction of Table 4 [1]. Statistics for the plot-wise averaged CSM-derived plant heights and destructively taken biomass for the reduced data sets of 2013 and 2014 (n: number of samples; $\overline{X}$: mean value; min: minimum; max: maximum; SD: standard deviation).

		CSM-Derived Plant Height (m)				Fresh Biomass (g/m²)				Dry Biomass (g/m²)
	n	$\overline{\mathit{X}}$	min	max	SD	$\overline{\mathbf{X}}$	min	max	SD	$\overline{\mathit{X}}$	min	max	SD
2013
3	12	0.22	0.01	0.39	0.13	1282.92	491.00	2172.50	473.20	168.31	52.00	272.00	56.59
4	12	0.47	0.24	0.71	0.17	2891.54	1560.25	4465.50	806.12	415.31	205.00	725.00	146.02
5	12	0.78	0.58	0.99	0.13	5070.42	2668.75	7730.00	1561.62	883.38	434.50	1429.25	328.93
6	12	0.78	0.65	0.93	0.07	4631.73	2986.25	7655.75	1193.95	1258.88	886.75	1687.50	219.92
Mean pre-anthesis period						123.27	62.93	191.57	3081.63	1573.33	4789.33	946.98	489.00
Mean whole observed period						138.77	77.06	220.24	42.14	3469.15	1926.56	5505.94	1008.72
2014
2	36	0.17	0.12	0.25	0.03	656.28	266.25	1116.50	202.07	89.01	33.00	155.25	27.66
3	36	0.41	0.34	0.52	0.04	2227.08	1226.75	3236.50	531.72	289.83	165.75	417.75	66.03
4	36	0.63	0.53	0.70	0.04	2825.48	1643.75	4162.00	603.19	465.49	276.62	706.65	97.89
5	36	0.81	0.69	0.99	0.05	3185.13	2106.50	5433.25	687.74	777.23	486.35	1271.35	156.02
6	36	0.78	0.66	0.99	0.05	3569.34	1994.75	6044.00	898.59	1166.38	652.60	1876.35	276.46
Mean pre-anthesis period						88.94	52.43	139.48	2223.49	1310.81	3487.06	506.18	405.39
Mean whole observed period						99.71	57.90	159.94	23.72	2492.66	1447.60	3998.45	584.66

Table 1. Correction of Table 4 [1]. Statistics for the plot-wise averaged CSM-derived plant heights and destructively taken biomass for the reduced data sets of 2013 and 2014 (n: number of samples; $\overline{X}$: mean value; min: minimum; max: maximum; SD: standard deviation).

		CSM-Derived Plant Height (m)				Fresh Biomass (g/m²)				Dry Biomass (g/m²)
	n	$\overline{\mathit{X}}$	min	max	SD	$\overline{\mathbf{X}}$	min	max	SD	$\overline{\mathit{X}}$	min	max	SD
2013
3	12	0.22	0.01	0.39	0.13	1282.92	491.00	2172.50	473.20	168.31	52.00	272.00	56.59
4	12	0.47	0.24	0.71	0.17	2891.54	1560.25	4465.50	806.12	415.31	205.00	725.00	146.02
5	12	0.78	0.58	0.99	0.13	5070.42	2668.75	7730.00	1561.62	883.38	434.50	1429.25	328.93
6	12	0.78	0.65	0.93	0.07	4631.73	2986.25	7655.75	1193.95	1258.88	886.75	1687.50	219.92
Mean pre-anthesis period						123.27	62.93	191.57	3081.63	1573.33	4789.33	946.98	489.00
Mean whole observed period						138.77	77.06	220.24	42.14	3469.15	1926.56	5505.94	1008.72
2014
2	36	0.17	0.12	0.25	0.03	656.28	266.25	1116.50	202.07	89.01	33.00	155.25	27.66
3	36	0.41	0.34	0.52	0.04	2227.08	1226.75	3236.50	531.72	289.83	165.75	417.75	66.03
4	36	0.63	0.53	0.70	0.04	2825.48	1643.75	4162.00	603.19	465.49	276.62	706.65	97.89
5	36	0.81	0.69	0.99	0.05	3185.13	2106.50	5433.25	687.74	777.23	486.35	1271.35	156.02
6	36	0.78	0.66	0.99	0.05	3569.34	1994.75	6044.00	898.59	1166.38	652.60	1876.35	276.46
Mean pre-anthesis period						88.94	52.43	139.48	2223.49	1310.81	3487.06	506.18	405.39
Mean whole observed period						99.71	57.90	159.94	23.72	2492.66	1447.60	3998.45	584.66

Table 2. Correction of Table 5 [1]. Statistics for the model calibration as mean values of the four subset combinations (R²: coefficient of determination; SE_E: standard error of the estimate).

		Bivariate BRMs					Multivariate BRMs
			Whole Period		Pre-Anthesis			Whole Period		Pre-Anthesis
		Estimator	R2	SEE a	R2	SEE a	Estimator b	R2	SEE a	R2	SEE a
Dry biomass	Linear	PH	0.65	250.71	0.76	143.34
		GnyLi	0.52	293.80	0.68	166.75	GnyLi	0.65	865.76	0.77	635.30
		NDVI	0.07	409.44	0.34	239.09	NDVI	0.69	537.36	0.76	518.25
		NRI	0.54	289.57	0.70	159.97	NRI	0.65	876.08	0.77	621.60
		RDVI	0.13	396.88	0.39	230.33	RDVI	0.69	479.48	0.76	535.08
		REIP	0.12	398.08	0.58	189.95	REIP	0.73	48353.45	0.76	6462.41
		RGBVI	0.05	413.80	0.26	252.59	RGBVI	0.68	557.08	0.76	580.76
	Exponential	PH	0.84	0.37	0.84	0.34	PH
		GnyLi	0.80	0.42	0.85	0.32	GnyLi	0.86	2.43	0.88	2.14
		NDVI	0.30	0.77	0.61	0.53	NDVI	0.85	2.85	0.88	3.99
		NRI	0.81	0.40	0.87	0.30	NRI	0.87	2.29	0.89	1.96
		RDVI	0.41	0.71	0.68	0.48	RDVI	0.85	2.52	0.88	2.84
		REIP	0.37	0.73	0.77	0.40	REIP	0.84	30.39	0.86	48.43
		RGBVI	0.23	0.81	0.48	0.60	RGBVI	0.85	2.51	0.87	2.73
		Estimator	R2	SEE a	R2	SEE a	Estimator b	R2	SEE a	R2	SEE a
Fresh biomass	Linear	PH	0.59	901.99	0.60	843.32
		GnyLi	0.58	913.81	0.62	829.48	GnyLi	0.62	3295.30	0.64	2968.91
		NDVI	0.25	1222.39	0.42	1022.79	NDVI	0.60	4561.69	0.63	5008.60
		NRI	0.59	909.94	0.62	821.35	NRI	0.62	3056.34	0.64	2718.09
		RDVI	0.35	1143.49	0.50	945.26	RDVI	0.61	3813.94	0.64	3955.80
		REIP	0.30	1180.82	0.55	894.62	REIP	0.60	14599.87	0.63	59169.39
		RGBVI	0.22	1243.84	0.37	1066.53	RGBVI	0.61	4007.93	0.64	3881.46
	Exponential	PH	0.70	0.37	0.68	0.39	PH
		GnyLi	0.76	0.33	0.76	0.34	GnyLi	0.77	1.87	0.77	1.77
		NDVI	0.46	0.50	0.65	0.41	NDVI	0.77	3.74	0.79	4.30
		NRI	0.77	0.33	0.77	0.33	NRI	0.77	1.67	0.77	1.56
		RDVI	0.59	0.43	0.74	0.35	RDVI	0.79	2.69	0.82	2.89
		REIP	0.47	0.49	0.71	0.37	REIP	0.72	22.27	0.74	73.05
		RGBVI	0.38	0.53	0.55	0.47	RGBVI	0.77	2.58	0.78	2.68

^a The SE_E for exponential models is calculated from natural log-transformed biomass values; ^b each fused with PH.

Table 2. Correction of Table 5 [1]. Statistics for the model calibration as mean values of the four subset combinations (R²: coefficient of determination; SE_E: standard error of the estimate).

		Bivariate BRMs					Multivariate BRMs
			Whole Period		Pre-Anthesis			Whole Period		Pre-Anthesis
		Estimator	R2	SEE a	R2	SEE a	Estimator b	R2	SEE a	R2	SEE a
Dry biomass	Linear	PH	0.65	250.71	0.76	143.34
		GnyLi	0.52	293.80	0.68	166.75	GnyLi	0.65	865.76	0.77	635.30
		NDVI	0.07	409.44	0.34	239.09	NDVI	0.69	537.36	0.76	518.25
		NRI	0.54	289.57	0.70	159.97	NRI	0.65	876.08	0.77	621.60
		RDVI	0.13	396.88	0.39	230.33	RDVI	0.69	479.48	0.76	535.08
		REIP	0.12	398.08	0.58	189.95	REIP	0.73	48353.45	0.76	6462.41
		RGBVI	0.05	413.80	0.26	252.59	RGBVI	0.68	557.08	0.76	580.76
	Exponential	PH	0.84	0.37	0.84	0.34	PH
		GnyLi	0.80	0.42	0.85	0.32	GnyLi	0.86	2.43	0.88	2.14
		NDVI	0.30	0.77	0.61	0.53	NDVI	0.85	2.85	0.88	3.99
		NRI	0.81	0.40	0.87	0.30	NRI	0.87	2.29	0.89	1.96
		RDVI	0.41	0.71	0.68	0.48	RDVI	0.85	2.52	0.88	2.84
		REIP	0.37	0.73	0.77	0.40	REIP	0.84	30.39	0.86	48.43
		RGBVI	0.23	0.81	0.48	0.60	RGBVI	0.85	2.51	0.87	2.73
		Estimator	R2	SEE a	R2	SEE a	Estimator b	R2	SEE a	R2	SEE a
Fresh biomass	Linear	PH	0.59	901.99	0.60	843.32
		GnyLi	0.58	913.81	0.62	829.48	GnyLi	0.62	3295.30	0.64	2968.91
		NDVI	0.25	1222.39	0.42	1022.79	NDVI	0.60	4561.69	0.63	5008.60
		NRI	0.59	909.94	0.62	821.35	NRI	0.62	3056.34	0.64	2718.09
		RDVI	0.35	1143.49	0.50	945.26	RDVI	0.61	3813.94	0.64	3955.80
		REIP	0.30	1180.82	0.55	894.62	REIP	0.60	14599.87	0.63	59169.39
		RGBVI	0.22	1243.84	0.37	1066.53	RGBVI	0.61	4007.93	0.64	3881.46
	Exponential	PH	0.70	0.37	0.68	0.39	PH
		GnyLi	0.76	0.33	0.76	0.34	GnyLi	0.77	1.87	0.77	1.77
		NDVI	0.46	0.50	0.65	0.41	NDVI	0.77	3.74	0.79	4.30
		NRI	0.77	0.33	0.77	0.33	NRI	0.77	1.67	0.77	1.56
		RDVI	0.59	0.43	0.74	0.35	RDVI	0.79	2.69	0.82	2.89
		REIP	0.47	0.49	0.71	0.37	REIP	0.72	22.27	0.74	73.05
		RGBVI	0.38	0.53	0.55	0.47	RGBVI	0.77	2.58	0.78	2.68

^a The SE_E for exponential models is calculated from natural log-transformed biomass values; ^b each fused with PH.

Table 3. Correction of Table 6 [1]. Statistics for the model validation as mean values of the four subset combinations (R²: coefficient of determination; RMSE: root mean square error (g/m²); d: Willmott’s index of agreement).

		Bivariate BRMs							Multivariate BRMs
			Whole Period			Pre-Anthesis				Whole Period			Pre-Anthesis
		Estimator	R2	RMSE a	d	R2	RMSE a	d	Estimator b	R2	RMSE a	d	R2	RMSE a	d
Dry biomass	Linear	PH	0.66	257.57	0.88	0.80	147.75	0.92
		GnyLi	0.54	299.67	0.81	0.72	173.31	0.88	GnyLi	0.65	262.19	0.88	0.79	148.20	0.92
		NDVI	0.07	412.70	0.33	0.38	244.47	0.64	NDVI	0.71	250.35	0.89	0.80	148.32	0.92
		NRI	0.55	295.41	0.82	0.74	166.41	0.89	NRI	0.66	261.77	0.88	0.80	147.67	0.92
		RDVI	0.13	400.36	0.44	0.41	233.53	0.71	RDVI	0.72	247.16	0.89	0.80	148.27	0.92
		REIP	0.15	404.95	0.46	0.68	197.50	0.83	REIP	0.73	228.46	0.91	0.80	147.88	0.92
		RGBVI	0.04	416.42	0.26	0.28	254.41	0.58	RGBVI	0.70	261.30	0.88	0.80	149.33	0.92
	Exponential	PH	0.85	0.39	0.95	0.85	0.36	0.95
		GnyLi	0.80	0.42	0.94	0.86	0.33	0.95	GnyLi	0.87	0.36	0.96	0.89	0.31	0.96
		NDVI	0.29	0.77	0.63	0.59	0.54	0.81	NDVI	0.85	0.38	0.95	0.87	0.30	0.96
		NRI	0.81	0.40	0.94	0.87	0.31	0.96	NRI	0.87	0.36	0.96	0.89	0.29	0.96
		RDVI	0.40	0.71	0.73	0.66	0.48	0.87	RDVI	0.85	0.38	0.95	0.88	0.30	0.96
		REIP	0.40	0.75	0.72	0.82	0.43	0.90	REIP	0.85	0.39	0.95	0.89	0.34	0.95
		RGBVI	0.22	0.82	0.55	0.48	0.62	0.75	RGBVI	0.85	0.38	0.95	0.86	0.31	0.96
		Estimator	R2	RMSE a	d	R2	RMSE a	d	Estimator b	R2	RMSE a	d	R2	RMSE a	d
Fresh biomass	Linear	PH	0.67	963.45	0.84	0.70	892.55	0.85
		GnyLi	0.65	970.70	0.83	0.72	886.24	0.84	GnyLi	0.69	939.84	0.85	0.74	861.73	0.86
		NDVI	0.27	1254.02	0.58	0.51	1053.83	0.70	NDVI	0.67	952.58	0.84	0.73	862.84	0.85
		NRI	0.65	962.49	0.83	0.72	873.75	0.85	NRI	0.69	938.46	0.85	0.74	857.99	0.86
		RDVI	0.38	1175.32	0.67	0.59	964.42	0.77	RDVI	0.68	943.96	0.85	0.74	841.36	0.86
		REIP	0.41	1244.11	0.66	0.77	951.74	0.81	REIP	0.67	966.67	0.84	0.77	908.74	0.84
		RGBVI	0.21	1260.32	0.53	0.41	1066.26	0.67	RGBVI	0.66	948.90	0.85	0.71	852.97	0.86
	Exponential	PH	0.73	0.40	0.89	0.71	0.42	0.88
		GnyLi	0.78	0.35	0.92	0.79	0.36	0.91	GnyLi	0.79	0.34	0.92	0.80	0.36	0.92
		NDVI	0.44	0.51	0.73	0.64	0.42	0.83	NDVI	0.78	0.34	0.92	0.79	0.34	0.92
		NRI	0.77	0.34	0.92	0.79	0.35	0.92	NRI	0.79	0.34	0.92	0.79	0.35	0.92
		RDVI	0.57	0.44	0.82	0.73	0.36	0.89	RDVI	0.80	0.33	0.93	0.83	0.31	0.93
		REIP	0.54	0.53	0.77	0.82	0.42	0.87	REIP	0.77	0.39	0.90	0.82	0.40	0.88
		RGBVI	0.36	0.54	0.68	0.53	0.47	0.78	RGBVI	0.76	0.34	0.92	0.76	0.34	0.92

^a The RMSE for exponential models is calculated from natural log-transformed biomass values; ^b each fused with PH.

Table 3. Correction of Table 6 [1]. Statistics for the model validation as mean values of the four subset combinations (R²: coefficient of determination; RMSE: root mean square error (g/m²); d: Willmott’s index of agreement).

		Bivariate BRMs							Multivariate BRMs
			Whole Period			Pre-Anthesis				Whole Period			Pre-Anthesis
		Estimator	R2	RMSE a	d	R2	RMSE a	d	Estimator b	R2	RMSE a	d	R2	RMSE a	d
Dry biomass	Linear	PH	0.66	257.57	0.88	0.80	147.75	0.92
		GnyLi	0.54	299.67	0.81	0.72	173.31	0.88	GnyLi	0.65	262.19	0.88	0.79	148.20	0.92
		NDVI	0.07	412.70	0.33	0.38	244.47	0.64	NDVI	0.71	250.35	0.89	0.80	148.32	0.92
		NRI	0.55	295.41	0.82	0.74	166.41	0.89	NRI	0.66	261.77	0.88	0.80	147.67	0.92
		RDVI	0.13	400.36	0.44	0.41	233.53	0.71	RDVI	0.72	247.16	0.89	0.80	148.27	0.92
		REIP	0.15	404.95	0.46	0.68	197.50	0.83	REIP	0.73	228.46	0.91	0.80	147.88	0.92
		RGBVI	0.04	416.42	0.26	0.28	254.41	0.58	RGBVI	0.70	261.30	0.88	0.80	149.33	0.92
	Exponential	PH	0.85	0.39	0.95	0.85	0.36	0.95
		GnyLi	0.80	0.42	0.94	0.86	0.33	0.95	GnyLi	0.87	0.36	0.96	0.89	0.31	0.96
		NDVI	0.29	0.77	0.63	0.59	0.54	0.81	NDVI	0.85	0.38	0.95	0.87	0.30	0.96
		NRI	0.81	0.40	0.94	0.87	0.31	0.96	NRI	0.87	0.36	0.96	0.89	0.29	0.96
		RDVI	0.40	0.71	0.73	0.66	0.48	0.87	RDVI	0.85	0.38	0.95	0.88	0.30	0.96
		REIP	0.40	0.75	0.72	0.82	0.43	0.90	REIP	0.85	0.39	0.95	0.89	0.34	0.95
		RGBVI	0.22	0.82	0.55	0.48	0.62	0.75	RGBVI	0.85	0.38	0.95	0.86	0.31	0.96
		Estimator	R2	RMSE a	d	R2	RMSE a	d	Estimator b	R2	RMSE a	d	R2	RMSE a	d
Fresh biomass	Linear	PH	0.67	963.45	0.84	0.70	892.55	0.85
		GnyLi	0.65	970.70	0.83	0.72	886.24	0.84	GnyLi	0.69	939.84	0.85	0.74	861.73	0.86
		NDVI	0.27	1254.02	0.58	0.51	1053.83	0.70	NDVI	0.67	952.58	0.84	0.73	862.84	0.85
		NRI	0.65	962.49	0.83	0.72	873.75	0.85	NRI	0.69	938.46	0.85	0.74	857.99	0.86
		RDVI	0.38	1175.32	0.67	0.59	964.42	0.77	RDVI	0.68	943.96	0.85	0.74	841.36	0.86
		REIP	0.41	1244.11	0.66	0.77	951.74	0.81	REIP	0.67	966.67	0.84	0.77	908.74	0.84
		RGBVI	0.21	1260.32	0.53	0.41	1066.26	0.67	RGBVI	0.66	948.90	0.85	0.71	852.97	0.86
	Exponential	PH	0.73	0.40	0.89	0.71	0.42	0.88
		GnyLi	0.78	0.35	0.92	0.79	0.36	0.91	GnyLi	0.79	0.34	0.92	0.80	0.36	0.92
		NDVI	0.44	0.51	0.73	0.64	0.42	0.83	NDVI	0.78	0.34	0.92	0.79	0.34	0.92
		NRI	0.77	0.34	0.92	0.79	0.35	0.92	NRI	0.79	0.34	0.92	0.79	0.35	0.92
		RDVI	0.57	0.44	0.82	0.73	0.36	0.89	RDVI	0.80	0.33	0.93	0.83	0.31	0.93
		REIP	0.54	0.53	0.77	0.82	0.42	0.87	REIP	0.77	0.39	0.90	0.82	0.40	0.88
		RGBVI	0.36	0.54	0.68	0.53	0.47	0.78	RGBVI	0.76	0.34	0.92	0.76	0.34	0.92

^a The RMSE for exponential models is calculated from natural log-transformed biomass values; ^b each fused with PH.

Figure 1. Correction of Figure 5 [1]. Scatterplots of measured vs. estimated dry biomass for one validation data set for NDVI, RGBVI, REIP, and GnyLi (exponential model). Pre-anthesis: crosses and solid green line; whole observed period: circles and dashed black line; 1:1 line: light grey.

Figure 1. Correction of Figure 5 [1]. Scatterplots of measured vs. estimated dry biomass for one validation data set for NDVI, RGBVI, REIP, and GnyLi (exponential model). Pre-anthesis: crosses and solid green line; whole observed period: circles and dashed black line; 1:1 line: light grey.

Figure 2. Correction of Figure 6 [1]. Scatterplots of measured vs. estimated fresh biomass for one validation data set for NDVI, RGBVI, REIP, and GnyLi (exponential model). Pre-anthesis: crosses and solid green line; whole observed period: circles and dashed black line; 1:1 line: light grey.

Figure 2. Correction of Figure 6 [1]. Scatterplots of measured vs. estimated fresh biomass for one validation data set for NDVI, RGBVI, REIP, and GnyLi (exponential model). Pre-anthesis: crosses and solid green line; whole observed period: circles and dashed black line; 1:1 line: light grey.

Figure 3. Correction of Figure 7 [1]. Scatterplot for one validation data set for the pre-anthesis (green) and for the whole observed period (black) of the bivariate BRM of PH (circles and solid regression line) and multivariate BRM of PH and GnyLi (crosses and dashed regression line) for fresh biomass (top) and dry biomass (bottom) (all exponential models); 1:1 line: light grey.

Figure 3. Correction of Figure 7 [1]. Scatterplot for one validation data set for the pre-anthesis (green) and for the whole observed period (black) of the bivariate BRM of PH (circles and solid regression line) and multivariate BRM of PH and GnyLi (crosses and dashed regression line) for fresh biomass (top) and dry biomass (bottom) (all exponential models); 1:1 line: light grey.