)04 
Application of Distance Based Vegetation index For Agricultural Crops Discrimination 
P Srinivas* BK Das, J Saibaba and R Krishnan 
ADRIN (Department Of Space) 
203, Akbar Road, Tarbund 
Manovikas Nagar ( P.O) 
Secunderabad — 500 009 
INDIA 
srinivas12 
* e-mail : 3in@ 
     
KEY WORDS: Vegetation index, WDVI, NDVI, wheat, poppy, season 
ABSTRACT: 
Among several vegetation indices, NDVI is the most extensively used index because of its ratioing properties and as it is simple to 
compute. But its usefulness in discriminating vegetation types with high cover density or high LAI (for example opium poppy and 
winter wheat) is limited due to saturation of NDVI values, insensitivity at high LAI’s and variations in canopy density, resulting in 
confusion between crops like those mentioned above. Due to these limitations discriminating between poppy and wheat using NDVI 
is a problem. Weighted Difference Vegetation Index (WDVI) counters these limitations effectively by enhancing canopy reflectance 
component. The application of WDVI is Observed to maximize the separation between winter wheat and opium poppy. The 
developed method is applied on IRS-1D LISS-III data sets covering parts of Madhya Pradesh and Rajasthan, India. For operational 
use of this index, interactive identification of soil pixels is tedious and error prone. To circumvent this difficulty authors propose a 
method for automatic extraction of soil and vegetation pixels using two date multispectral data (acquired during fallow and crop 
season). For automatic extraction of soil and vegetation pixels a modified version of WDVI, called as Inverse WDVI (IWDVI]), 
termed as corrected red, is proposed. Advantages of this procedure are automatic identification of soil and crop land pixels. 
1. INTRODUCTION 
Opium poppy crop is cultivated in quite a few countries all 
over the world. The major opium producing countries are in 
  
  
; : es b, ; Satellite Sensor Spectral Spatial Swath | Revisit 
Asia. In India legal cultivation of opium poppy takes place in bands Resolution | (km) 
Madhaya Pradesh, Rajasthan and Uttar Pradesh under the (mt) 
supervision of Government of India officials. Ground IRS- LISS. Green 23,5 141 24 
Surveys are conducted from time to time during the crop ICAD! | my Red 
season to monitor cultivation activity. Remote sensing Near IR 
technology provides an alternative to expensive, time Middle IR | 70 
consuming ground surveys and also offers an opportunity for 
independent validation of Crop acreage. Medium to high a GE 810 
spatial resolution multispectral data provided by remote RSP TI SUR $$ 
sensing satellites, like, IRS-1C/1D LISS-III to recently s IV = v 
launched IRS-P6 (sensor details onboard these satellites are 
  
    
   
    
Red 
Near IR 
       
  
  
  
  
  
shown in TABLE.1) are useful to monitor the crop. Crop LISS- Green 333 
acreage estimates at range level (comprising of eight to ten IH Red 
villages) and under certain conditions at village level with Near IR 
reasonable accuracy can be obtained using medium spatial Middle IR 
resolution multi spectral data like IRS-1C/1D LISS-III. For AwiFS | Green 56 2700 [5 
cultivator level information one needs to use IRS-P6 LISS- Red 
IV data or any other multi spectral data having comparable Tm 
  
  
spatial resolution. The multispectral bands provide useful 
spectral contrast among several terrain features, which can be 
exploited by employing digital image processing techniques. 
Table I. Sensor characteristics 
GREEN (0.52um — 0.59um), RED (0.62um — 0.68um), Near 
Infra red (0.77um — 0.86pm), Middle IR (1.55um — 1.70pm) 
2. CROP CALENDAR AND GEOGRAPHIC AREA 
Information regarding crop calendar for a given Lancing (process of extracting opium gum) generally 
geographic area is important as it helps in identifying begins during first week of March and about four lancings 
period of peak vegetative cover for crop of interest and are carried out during a period of 15 to 20 days. If license 
status of competing crops during that time. This type of is issued late, sowing can happen as late as first week of 
information is vital in selecting appropriate image data December and yield in this case will be low due to reduced 
sets. Opium poppy crop in Madhya Pradesh and Rajasthan number of lancings. Ground water is the major source of 
is sown during October/November, flowering takes place irrigation in this area. In the fields adjacent to poppy other 
around January end and lasts for about seven to ten days. crops like wheat, garlic, onion, vegetables, mustard, pulses 
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