Polarization Signature Analysis of Paddy Rice in Southern China

Chou Xie, Yun Shao, Kun Li, Fengli Zhang, Junna YuanInstitute of Remote Sensing Applications,

Chinese Academy of Sciences, China

Maosong Xu, Xuejun Wang, Zhongsheng XiaState Forestry Administration, China

Outlines

Introduction

Objectives

Radarsat 2: Polarimetric Signature Analysis of Paddy Rice in Guizhou Test Site

Airborne SAR Data: Polarization Behavior Analysis of Paddy Rice in Hainan Test Site

Conclusions

Outlines

Introduction

Rice is the staple food of more than half population of the world.

Most of Rice grows in cloud-prone and rainy areas : great potential of SAR, especially polarimetric SAR.

Two test sites were selected for this study in southern China

Guizhou

Hainan

One step forward from Multitemporal Radarsat 1 rice mapping

Understand the polarimetric signature of paddy rice in south China

Explore the potentiality of polarimetric Radarsat 2 in rice mapping

Rice acreage survey Rice yield estimation

Objectives

Radarsat 2: Polarimetric Signature Analysis of Paddy Rice in Guizhou Test Site

Guizhou Test Site:

Located in Zhazuo, Guizhou province, typical mountainous area with Karst Landform Small rice fields distribute in the flat bottom area of valleys Two type of rice: hybrid rice and japonica rice One rice crop a year, Growing season: May to October

Hybrid rice Japonica rice

RADARSAT-2 Acquisitions (supported by SOAR Program)

Acquisitiontime

BeamMode

Incidenceangle

(degrees)

Resolution (m)

Range Azimuth

July 26,2009 FQ 40.34 12m 8m

August 19,2009 FQ 40.34 12m 8m

September 12,2009

FQ 40.34 12m 8m

October 6,2009 FQ 40.34 12m 8m

Rice fields

Rice fields

Linear Polarization Combination

HH – HV space:

good combination of polarizations

Linear Polarization RatiosThe HH/HV improves the discrimination between rice and other targets;

Combination of HH and HH/HV is the best combination

HH and HH/HV Color Composite Image (R:HH G:VH B:HH/HV)

Rice=purple magenta=building1 yellow=buiding2 green=forest

Polarization information is a unique advantage of SAR

Polarization decomposition can be use to analyze the physical scattering mechanisms of the targets, and then carry out a variety of processing and applications.

Polarization decomposition methods are mainly divided into

two categories, one is coherent decomposition, the other is

incoherent decomposition.

The Pauli decomposition (coherent decomposition) and

Cloude decomposition (incoherent decomposition) were

applied in this study,

Radarsat 2: Polarimetric Signature Analysis of Paddy Rice in Guizhou Test Site

Pauli Decomposition

Color composite image red=a scattering mechanism characterized by double- or even-bouncegreen= those scatters which are able to return the orthogonal polarization, from which, one of the best examples is the volume scattering produced by the forest canopy. blue =power scattered by targets characterized by single- or odd-bounce.

Rice fields

Rice fields

Polarimetric signature of four major targets

rice forest

urban water

H-Alpha space of four major targets

forestrice

urban water

Entropy, Anisotropy and combinations

Entropy H Anisotropy A

HA H(1-A)

Color composite image highlighting rice （ R :HA ， G:Pauli-G ， B: Pauli-B ）

Rice=red magenta=building1 yellow=buiding2 green=forest

image

So far, parameter does not have very clear physical meaning to explain scattering mechanisms of rice. But it shows rice fields correctly.

It is sensitivity to terrain. In the test site (mountainous area), rice fields are relatively flat compared to other features.

Color composite image highlighting rice （ R : ， G:Pauli-G ， B: Pauli-B ）

Rice=red magenta =building1 yellow=buiding2 green=forest water=black

Temporal Polarization signature of rice

July 26th,2009 Aug 19th,2009

Sep 12th,2009 Oct 6th,2009

Temporal H-Alpha space of rice

July 26th,2009

Aug 19th,2009

Sep 12th,2009

Oct 6th,2009

Located in southeast of

Hainan province

Large-scale rice cultivation

Large,regular rice fields

Three rice crops a year

Growing season:

February to June,

late June to September,

October to next January

Airborne SAR Data: Polarization Behavior Analysis of Paddy Rice in Hainan Test Site

Airborne SAR data acquisitions

Acquisition time Incidence angle (degrees)

Resolution (meter) Polarization

Range Azimuth

February 21th,2009 44.0—50.9 2 2 HH/HV/VH/VV

February 27th,2009 33.0—44.0 2 2 HH/HV/VH/VV

February 28th,2009 33.9—44.8 2 2 HH/HV/VH/VV

March 9th,2009 54.0—65.5 2 2 HH/HV/VH/VV

March 9th,2009 50.5—63.4 2 2 HH/HV/VH/VV

March 9th,2009 48.3—62.0 2 2 HH/HV/VH/VV

March 9th,2009 47.5—66.8 2 2 HH/HV/VH/VV

March 10th,2009 47.5—66.8 2 2 HH/HV/VH/VV

Color composite image （ R:HH G:HV B:VV ）

Rice on different polarization images

HH

VH

HV

VV

rice

Linear Polarization Ratios image—HH/VV

Rice in different growth stages<HH>/ <VV> of ri ce wi th di ff erent stages

0

0. 5

1

1. 5

2

2. 5

3

3. 5

4

58. 5 60 61 70 80 85The hei ght of ri ce (cm)

<HH>

/<VV

> (d

B)

<HH>/ <VV>

<HH> / <VV> of rice increases with rice growthdistinguish rice in different growing stages

rice1=60 days rice2= 40 days rice3=30 days rice4=20 days The accuracy of rice extraction is 90%, and the precision of classification is 71%.

Liner polarization combination, Polarization decomposition is effective in rice discrimination

Paddy rice mapping is feasible with polarimetric Radarsat 2 data in mountainous areas

Polarimetric signature, parameters delivered from polarization decomposition (coherent or incoherent decomposition) need further study, understanding and exploring

It is better to provide final results, maps and services to the end users instead of provide SAR data to them

Conclusions

ThanksThanks!!Chou XieChou Xie

Institute of Remote Sensing Applications, Institute of Remote Sensing Applications, Chinese Academy of SciencesChinese Academy of Sciences

Tel:86-10-64876313Tel:86-10-64876313Email:xiechou@irsa.ac.cnEmail:xiechou@irsa.ac.cn