Monitoring Crops Using Compact Polarimetry and the RADARSAT Constellation Mission

Figures & data

Figure 1. Schematic of Poincaré sphere (adapted from https://www.thorlabschina.cn/newgrouppage9.cfm?objectgroup_id=142)00).

Figure 2. (a) Agriculture extent of Canada as mapped by AAFC since 2009, (b) location of Kenaston within the province of Saskatchewan and (c) RCM multi-temporal composite of the Kenaston study site.

Table 1. BBCH phenology categories.

BBCH primary category	Growth stage description
	Canola	Wheat	Peas/Lentils
00	Germination	Germination	Germination
10	Leaf development	Leaf development	Leaf development
20	Formation of side shoots	Tillering
30	Stem elongation	Stem elongation	Stem elongation
40		Booting
50	Inflorescence emergence	Inflorescence emergence, heading	Inflorescence emergence
60	Flowering	Flowering	Flowering
70	Development of fruit	Development of fruit	Development of fruit
80	Ripening	Ripening	Ripening
90	Senescence	Senescence	Senescence

Table 2. Numbers of ground observations per crop type.

	Fields		Pixels
	Training	Validation	Training	Validation
Pasture/Forage	40	22	7247	4014
Barley	42	20	7658	3657
Wheat	41	27	7453	4912
Canola	383	158	69607	28709
Flaxseed	17	8	3106	1447
Peas	67	32	12131	5701
Lentils	220	110	39956	19885

Table 3. RCM image acquisition dates. All dates were used for crop classification.

	RCM1 30mCP B mode	RCM2 30mCP B mode	RCM2 30mCP C mode	RCM3 30mCP B mode	RCM3 30mCP C mode
June	12*, 24*	16*	9		1
July		10*, 14*, 26		6*, 18*, 30*	1
August	27*	7*	2, 31	11*

Dates indicated with * were used in the interpretation of Stokes parameters with respect to crop phenology.

Table 4. List of parameters included in the classification runs.

Parameter	Definition
Stokes 0	$S_0=〈{\left|E_{RH}\right|}^2+ {\left|E_{RV}\right|}^2〉$
Stokes 1	$S_1=〈{\left|E_{RH}\right|}^2- {\left|E_{RV}\right|}^2〉$ $= m{S}_o \hspace{0.17em}\mathit{\text{cos}}\hspace{0.17em}2\chi \hspace{0.17em}\mathit{\text{cos}}\hspace{0.17em}2\psi$
Stokes 2	$S_2=2\mathit{\text{ Re }}〈E_{RH}{E}_{RV}^{*}〉= m{S}_o \hspace{0.17em}\mathit{\text{cos}}\hspace{0.17em}2\chi \hspace{0.17em}\mathit{\text{sin}}\hspace{0.17em}2\psi$
Stokes 3	$S_3=2\mathit{\text{ Im }}〈E_{RH}{E}_{RV}^{*}〉= m{S}_o\hspace{0.17em}\mathit{\text{sin}}\hspace{0.17em}2\chi$
m-Chi double bounce	$R^{2 }= m{S}_0 (1+\hspace{0.17em}\mathit{\text{sin}}\hspace{0.17em}2\chi )/2$
m-Chi volume scattering	$G^{2 }= S_0 (1-m)$
m-Chi single bounce	$B^{2 }= m{S}_0 (1-\hspace{0.17em}\mathit{\text{sin}}\hspace{0.17em}2\chi )/2$
RH	Intensity
RV	Intensity

Table 5. 2020 RCM data classifications in overall accuracy descending order.

	ACI		Stokes & M-chi CP Parameters		All M-chi		RH, RV, Stokes & M-chi CP Parameters		All Stokes Parameters
	UA	PA	UA	PA	UA	PA	UA	PA	UA	PA
Pasture/ Forage	97.96	90.00	91.48	86.31	89.59	87.18	92.41	87.40	94.13	83.23
Barley	92.88	92.49	94.36	91.81	93.10	91.01	96.74	86.48	96.02	88.24
Wheat	95.57	91.47	89.84	84.49	89.57	81.75	85.97	82.39	84.90	82.51
Canola	99.00	99.93	96.27	99.65	96.00	99.62	96.32	99.66	96.75	99.58
Flaxseed	88.49	74.91	98.77	49.97	98.66	50.26	89.33	40.80	96.29	41.86
Peas	97.29	96.49	99.16	87.83	98.77	87.30	99.46	88.28	99.03	87.90
Lentils	96.37	98.74	93.67	98.27	93.56	97.84	92.84	98.64	91.58	98.56
Overall Accuracy	97.26		94.91		94.55		94.50		94.29
Kappa Coefficient	0.96		0.93		0.92		0.92		0.92
	M-chi Volume Only		RH,RV		S1, S2 and S3		S0 Only
	UA	PA	UA	PA	UA	PA	UA	PA
Pasture/ Forage	82.44	83.54	93.18	79.23	93.31	79.55	89.53	78.03
	89.31	84.34	95.35	84.60	90.69	79.50	95.54	73.55
Barley	86.61	73.30	78.15	74.93	80.96	73.18	77.73	68.36
Wheat	95.90	99.56	95.89	99.15	94.70	99.33	96.48	99.49
Canola	78.58	41.04	82.09	27.87	88.42	34.19	61.42	18.53
Flaxseed	98.31	86.61	98.22	82.35	84.80	80.94	98.77	87.16
Peas	90.73	96.09	88.44	97.86	90.79	96.55	85.29	97.02
Lentils	92.59	92.17	91.50	91.14	93.56	97.84	92.84	98.64
Overall Accuracy	0.90		0.89		0.88		0.87
Kappa Coefficient	0.96		0.93		0.92		0.92

Overall accuracies, Kappa coefficients, users’ accuracies (UA) and producers’ accuracies (PA) are provided.

Figure 3. Classified map of the Kenaston study site using a Random Forest classifier and inputs of the four Stokes and three m-chi parameters generated using RCM CP images. 17 30mCP images were used to create this figure.

Table 6. Order of importance ranking from Random Forest classification.

	Crop types
	Pasture/Forage	Barley	Wheat	Canola	Flaxseed	Peas	Lentils	Overall
1	S0	S1	S1	S1	S0	S0	S3	S1
	Jun 1	Jul 26	Jul 26	Jul 14	Jun 1	Jul 6	Aug 2	Jul 1
2	S1	S2	S2	S2	S3	S2	S3	S2
	Jun 16	Jun 1	Jun 1	Jul 1	Jun 1	Jun 16	Aug 27	Jul 1
3	S2	S1	S2	S2	S1	S0	S3	S2
	Jun 1	Jul 14	Jun 16	Jun 9	Jul 26	Jul 18	Jun 1	Jun 9
4	S2	S3	S3	S1	S3	S0	S0	S3
	Jun 9	Aug 2	Aug 2	Jul 6	Aug 2	Aug 2	Aug 2	Jun 1
5	S2	S2	S3	S1	S2	S1	S3	S2
	Jul 1	Jun 9	Jul 30	Jul 1	Jun 9	Jul 1	Aug 31	Aug 31
6	S3	S2	S2	S2	S2	S0	S1	S1
	Aug 27	Aug 11	Jul 1	Aug 31	Jun 16	Jun 1	Jul 26	Jul 14
7	S1	S0	S3	S1	S2	S2	S1	S2
	Aug 31	Jun 1	Aug 27	Aug 2	Aug 11	Jul 1	Jul 14	Jun 1
8	S3	S3	S3	S2	S1	S3	S0	S1
	Aug 31	Jul 30	Jun 1	Jun 16	Jun 16	Jul 1	Jul 6	Jun 16
9	S2	S2	S1	S2	S2	S2	S3	S3
	Aug 11	Jun 16	Jul 14	Aug 27	Jul 1	Jun 1	Jul 30	Aug 27
10	S1	S0	S0	S3	S3	S1	S1	S3
	Jun 9	Jul 6	Jun 1	Jul 30	Jun 9	Jul 6	Jul 6	Aug 2

Contributing bands in declining order of importance, per class type and overall, with only S₀, S₁, S₂ and S₃ parameters in the classification. S₁ (light) and S₂ (dark) are highlighted in the importance ranking.

Figure 4. Plots of Degree of Polarization (DoP) for each date of RCM (CP Beam B) acquisition, acquired for the entire growing season. DoP is calculated using the Stokes parameters. Key phenological stages of growth are indicated for each crop type.

Figure 5. Mapping of development stages of canola (field P7) on projections of the Poincaré 3 D spheres. Projections include (a) Left Handed Circular (LHC); (b) 135o; and (c) Right Handed Circular (RHC). For the 135o projection, circular scattering is located at the poles, linear scattering at the equator and elliptical scattering in all other locations on the plot.

Figure 6. Mapping of crop development stages. Projections of the Poincaré sphere include Left Handed Circular (all crops) (left); 135o (lentils) or 00 (peas and wheat) (right).

Figure 7. Plots of absolute values of Stokes parameters S₁, S₂ and S₃. The point at which S₃ declines to values close to S₁ is indicated as is the phenology stage for this point.