Mapping fractional landscape soils and vegetation components from Hyperion satellite imagery using an unsupervised machine-learning workflow

Figures & data

Figure 1. Study area location and the portion of EO-1 Hyperion image used in the study (date of collection 2004/10/09; spectral bands centered in 1648.0, 823.0 and 661.0 nm in the RGB composition, respectively). Inset boxes represent priority regions of study at the pixel scale.

Figure 2. Independent field signatures of tropical soils and vegetation used in this study.

Figure 3. Flowchart for the unsupervised landscape mapping of tropical soils and vegetation.

Figure 4. Autocontractive results for tropical soils and vegetation presented as distances in a minimum spanning tree.

Figure 6. Clustering in the universal-distance matrix of SOM results. Individual clusters agree with the seven component types validating the stochastic SOM training process. Soil components: a) clay-rich Latosols (A16), (b) iron-rich Nitisols (A14), (c) quartz-rich Arenosols (A9); Vegetation components: (d) Forest 1 (Aspen), (e) Forest 2 (Blackbrush), (f) grass, and (g) dry grass. Individual clusters agree with the seven independent component types thereby validating the stochastic SOM training process.

Table 1. Classification of landscape components by SOM and different network sizes.

		Soil			Vegetation
		A14	A16	A9	Forest1	Forest2	Grass	GrassDry	Map
	A14	0 . 93	0.01	0.00	0.02	0.03	0.00	0.00	14 × 10
	A16	0.02	0.95	0.00	0.00	0.00	0.00	0.03
Soil	A20	0.32	0.68	0.00	0.00	0.00	0.00	0.00
	A21	0.18	0.75	0.00	0.01	0.00	0.00	0.06
	A27	0.02	0.98	0.00	0.00	0.00	0.00	0.00
	A13	0.00	0.00	0.87	0.13	0.00	0.00	0.00
	A9	0.00	0.00	0.99	0.00	0.00	0.00	0.01
	Aspen	0.00	0.00	0.02	0.92	0.06	0.00	0.00
Vegetation	Black	0.03	0.00	0.00	0.12	0.85	0.00	0.00
	Grass	0.00	0.01	0.00	0.00	0.15	0.84	0.00
	GrassDry	0.00	0.21	0.00	0.00	0.00	0.01	0.78
	A14	0.98	0.02	0.00	0.00	0.00	0.00	0.00	28 × 20
	A16	0.00	0.95	0.00	0.00	0.00	0.02	0.03
Soil	A20	0.29	0.71	0.00	0.00	0.00	0.00	0.00
	A21	0.18	0.82	0.00	0.00	0.00	0.00	0.00
	A27	0.02	0.98	0.00	0.00	0.00	0.00	0.00
	A13	0.00	0.00	0.93	0.07	0.00	0.00	0.00
	A9	0.00	0.00	1.00	0.00	0.00	0.00	0.00
	Aspen	0.00	0.00	0.00	0.90	0.10	0.00	0.00
Vegetation	Black	0.02	0.00	0.00	0.00	0.98	0.00	0.00
	Grass	0.00	0.00	0.00	0.00	0.00	1.00	0.00
	GrassDry	0.00	0.17	0.00	0.00	0.00	0.00	0.83
	A14	0.99	0.00	0.00	0.00	0.01	0.00	0.00	42 × 30
	A16	0.00	0.96	0.00	0.00	0.00	0.00	0.03
Soil	A20	0.35	0.65	0.00	0.00	0.00	0.00	0.00
	A21	0.00	1.00	0.00	0.00	0.00	0.00	0.00
	A27	0.00	0.99	0.00	0.01	0.00	0.00	0.00
	A13	0.00	0.00	1.00	0.00	0.00	0.00	0.00
	A9	0.00	0.00	1.00	0.00	0.00	0.00	0.00
	Aspen	0.00	0.00	0.00	0.99	0.02	0.00	0.00
Vegetation	Black	0.00	0.00	0.00	0.00	1.00	0.00	0.00
	Grass	0.00	0.00	0.00	0.00	0.40	0.60	0.00
	GrassDry	0.01	0.00	0.00	0.00	0.00	0.01	0.98

Note: Soil components: clay-rich Latosols (A16), iron-rich Nitisols (A14), quartz-rich Arenosols (A9); Vegetation components: Forest 1 (Aspen), Forest 2 (Black), grass (live), and (g) dry grass (GrassDry). Classification results are from 1 (perfect correspondence) to 0 (no correspondence).

Table 2. A summary table of classified landscape features according to prescribed pixel exceedances.

Exceedance fraction	Landscape feature	Description type	Number pixels	Area (km^2)	Percent
0.1	a14	Latosol (iron-rich soil)	37968	34.17	51
	a16	Nitisol (clay-rich soil)	56242	50.62	76
	a9	Arenosol (quartz-rich soil)	809	0.73	1
	forest1	Aspen (tree)	12140	10.93	16
	forest2	Blackberry (tree)	12949	11.65	17
	grass	Grass (live)	12282	11.05	16
	grassdry	Grass (dead)	3517	3.17	5
0.25	a14	Latosol (iron-rich soil)	31695	28.53	43
	a16	Nitisol (clay-rich soil)	55795	50.22	75
	a9	Arenosol (quartz-rich soil)	746	0.67	1
	forest1	Aspen (tree)	3304	2.97	4
	forest2	Blackberry (tree)	5563	5.01	7
	grass	Grass (live)	1	0.00	0
	grassdry	Grass (dead)	10343	9.31	14
0.5	a14	Latosol (iron-rich soil)	11431	10.29	15
	a16	Nitisol (clay-rich soil)	53335	48.00	72
	a9	Arenosol (quartz-rich soil)	519	0.47	1
	forest1	Aspen (tree)	3268	2.94	4
	forest2	Blackberry (tree)	5563	5.01	7
	grass	Grass (live)	0	0.00	0
	grassdry	Grass (dead)	1400	1.26	2
0.75	a14	Latosol (iron-rich soil)	1367	1.23	2
	a16	Nitisol (clay-rich soil)	32466	29.22	44
	a9	Arenosol (quartz-rich soil)	408	0.37	1
	forest1	Aspen (tree)	0	0.00	0
	forest2	Blackberry (tree)	11	0.01	0
	grass	Grass (live)	0	0.00	0
	grassdry	Grass (dead)	1393	1.25	2
0.9	a14	Latosol (iron-rich soil)	723	0.65	1
	a16	Nitisol (clay-rich soil)	23640	21.28	32
	a9	Arenosol (quartz-rich soil)	0	0.00	0
	forest1	Aspen (tree)	0	0.00	0
	forest2	Blackberry (tree)	11	0.01	0
	grass	Grass (live)	0	0.00	0
	grassdry	Grass (dead)	376	0.34	1

Figure 7. Classification of fractional landscape components in the Hyperion scene: (a) OE-1 Hyperion image (red, green, blue bands centered at 1648.0 nm, 823.0 nm and 661.0 nm), (b) quartz-rich Arenosols (A9), (c) iron-rich Nitisols (A14), (d) clay-rich Latosols (A16), (e) Forest1 (Aspen-like trees), (f) Forest1 (Blackberry-like trees), (g) FOREST (all), (h) GrassDry (nonphotosynthetically active), (i) Grass (photosynthetically active), (j) GRASS (all).

Figure 8. Field verification: (a) Location of Hyperion soil test areas (CC R650/G548/B477) and (b) crossplots of observed versus estimated Hyperion spectra for soils: (1) iron-rich Latosol, (2) vegetation, (3) clay-rich Nitosol, (4) quarts-richArenosol.

Figure 9. Mapping and verification of fractional landscape components in region 1 of the Hyperion scene: (a) Google Earth image, (b) quartz-rich Arenosols (A9), (c) iron-rich Nitisols (A14), (d) clay-rich Latosols (A16), (e) Forest1 (Aspen-like trees), (f) Forest1 (Blackberry-like trees), (g) FOREST (all), (h) GrassDry (nonphotosynthetically active), (i) Grass (photosynthetically active), (j) GRASS (all).

Figure 10. Mapping and verification of fractional landscape components in region 2 of the Hyperion scene: (a) Google Earth image, (b) quartz-rich Arenosols (A9), (c) iron-rich Nitisols (A14), (d) clay-rich Latosols (A16), (e) Forest1 (Aspen-like trees), (f) Forest1 (Blackberry-like trees), (g) FOREST (all), (h) GrassDry (nonphotosynthetically active), (i) Grass (photosynthetically active), (j) GRASS (all).

Figure 11. Mapping and verification of fractional landscape components in region 3 of the Hyperion scene: (a) Google Earth image, (b) quartz-rich Arenosols (A9), (c) iron-rich Nitisols (A14), (d) clay-rich Latosols (A16), (e) Forest1 (Aspen-like trees), (f) Forest1 (Blackberry-like trees), (g) FOREST (all).