Full text: Remote sensing for resources development and environmental management (Volume 1)

Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
56 sugar-beet ml „ 
57 turnip 
42 sugar-beet min 
' , R . ; 
>ns of spec- 
L objects 
obinoon, G.F. 
jricultu ral 
space, aerial 
at ional 
3. 1983. 
bee a 
ues daus les 
nes - 
res spec- 
83. Issledo- 
3: 120 - 
4. Metod 
zenki ugodij 
LANDSAT temporal-spectral profiles of crops 
on the South African Highveld 
Optical Sciences Division, Nat. Physical Research Lab., Pretoria, South Africa 
LANDSAT MSS data were standardized for variations in digital count coding between different receiving stations, 
satellite sensor response and solar illumination of the scene. The Kauth and Thomas approach has been used to 
obtain the independent variables of soil brightness, greenness and yellowness. The coefficients of the rota 
tion matrix were modified to suit local conditions. 
Three vegetation indices, the vegetation ratio, the normalized vegetation index and the greenness index have 
been determined on a field-by-field basis using data recorded on sixteen overpasses within thirteen months. An 
intercomparison of the spectral-temporal profiles for a variety of crops is in progress. A correlation between 
the spectral profiles and a ground reference set consisting of detailed information on planting, growth and 
environmental conditions is to be undertaken. 
The spectral separability of the crops in terms of the vegetation indices and the field conditions is being 
The need to develop objective, repeatable and time- 
efficient methods for crop identification has been 
recognized by researchers particularly in the United 
States of America since the 1970's. The identifica 
tion of cultivated crops from LANDSAT imagery has 
traditionally been accomplished by the recognition of 
certain crop characteristics which change throughout 
the growing season (i.e. temporal changes)(MacDonald 
and Hall, 1980). Success depends upon the correct 
estimation of the time of occurrence of a particular 
crop feature which is stable from year to year and 
which does not overlap with similar characteristics of 
other crops growing in the same geographic region. In 
the few cases where such features can be identified, a 
unique signature for each crop can be accurately and 
consistently defined (Malan and Turner, 1984). 
An alternative approach was introduced in 1976 when 
Kauth and Thomas (Kauth and Thomas, 1976) showed that 
a fixed two-dimensional subspace of the LANDSAT four- 
dimensional measurement space contained most of the 
spectral information for a very large range of agri 
cultural, seasonal and meteorological conditions 
(Hall, 1982). Furthermore, they proposed that two of 
the transformed axes of the subspace related to 
changes in scene brightness and changes in the leafy 
matter in the vegetative canopies. 
Other researchers (Jordan, 1969; Pearson, 1972; 
Rouse et al., 1973; Colwell, 1974; Maxwell, 1976; 
1978; Richardson and Wiegand 1977) have suggested cer 
tain mathematical combinations or vegetation indices 
in an attempt to establish a relationship between 
LANDSAT multispectral scanner (MSS) data and the 
ground cover canopy. 
It is also important to realize that there are a 
number of variables which significantly influence the 
data collected by earth orbiting satellites. For 
quantitative studies, methods of data analysis must be 
selected or developed to take the effects of these 
variables into account. 
In the present study, techniques which have been 
successful elsewhere have been applied to agricultural 
MSS data collected for the Highveld region of RSA. 
Control data concerning the characteristics of the 
crop canopy have been obtained from an agricultural 
survey conducted simultaneously with LANDSAT overpas 
ses by officers of the Highveld Region of the Depart 
Figure 1. Location of test area. 
ment of Agriculture (Malan and Turner, 1982). 
A correlation has been sought between time series 
of spectral reflectance properties of the vegetative 
cover as measured by LANDSAT MSS data and known 
features of the actual crops. 
2.1 Choice of test area 
The LANDSAT-scene identified by a code WRS 182-79 in

Note to user

Dear user,

In response to current developments in the web technology used by the Goobi viewer, the software no longer supports your browser.

Please use one of the following browsers to display this page correctly.

Thank you.